iOS
Group Channel Advanced

Group Channel: Advanced

This page explains the advanced features for group channels. Some of them are the premium features available only to a paying user.


Add other users as friends

A user can search and add other users as friends to chat with them in a simple way. In order to add friends, the user should first upload other users’ unique keys to SendBird server such as hashed phone numbers for privacy. When the unique keys are uploaded to the server, the server identifies and matches the corresponding users based on the uploaded keys, and then notifies the results to the matched users. Finally, the matched users can decide to add or ignore each other as friends.

Note: Before using this feature, the user information should already include unique keys. If not, update the user information with unique keys. We recommend you to include unique keys when first creating a user.

Objective-C
Swift
Light Color Skin
Copy
// Uploading other users' unique keys to SendBird server for discovering the corresponding users
NSMutableDictionary<NSString *, NSString *> *discoveryMap = [[NSMutableDictionary alloc] init]; // Store names of friends by unique key
discoveryMap[@"0001-0002-0003"] = @"John";  // A pair of a unique key and a friend's name
discoveryMap[@"0004-0005-0006"] = @"Jay";
discoveryMap[@"0007-0008-0009"] = @"Jin";

[SBDMain uploadFriendDiscoveries:discoveryMap completionHandler:^(SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];

// Ignoring particular users when SendBird server discovers the matched users  
NSMutableArray<NSString *> *discoveryKeys = [[NSMutableArray alloc] init]; 
[discoveryKeys addObject:@"0001-0002-0003"];
[discoveryKeys addObject:@"0004-0005-0006"];
[discoveryKeys addObject:@"0007-0008-0009"];

[SBDMain deleteFriendsWithDiscoveries:discoveryKeys completionHandler:^(SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
// Uploading other users' unique keys to SendBird server for discovering the corresponding users
var discoveryMap:[String:String] = [:]   // Store names of friends by unique key
discoveryMap["0001-0002-0003"] = "John" // A pair of a unique key and a friend's name
discoveryMap["0004-0005-0006"] = "Jay"
discoveryMap["0007-0008-0009"] = "Jin"

SBDMain.uploadFriendDiscoveries(discoveryMap) { (error) in
    guard error == nil else {   // Error.
        return
    }
}

// Ignoring particular users when SendBird server discovers the matched users  
var discoveryKeys:[String] = []
discoveryKeys.append("0001-0002-0003")
discoveryKeys.append("0004-0005-0006")
discoveryKeys.append("0007-0008-0009")

SBDMain.deleteFriends(withDiscoveries: discoveryKeys) { (error) in
    guard error == nil else {   // Error.
        return
    }
}

Through the didDiscoverFriends: of a user event delegate, the current user will receive a callback from the server, which contains a list of users matching the uploaded keys. Based on the list, you can add the matched users as friends by the addFriendsWithUserIds:userIds:completionHandler: method:

Objective-C
Swift
Light Color Skin
Copy
// ViewController.m
@interface ViewController : UIViewController<SBDConnectionDelegate, SBDUserEventDelegate, SBDChannelDelegate>

@end

@implementation ViewController

- (void)initViewController {
    // ...
    [SBDMain addUserEventDelegate:self identifier:UNIQUE_DELEGATE_ID];
    // ...
}

- (void)didDiscoverFriends:(NSArray<SBDUser *> * _Nullable)friends {
    if (friend != nil) {
        NSMutableArray<NSString *> *userIds = [[NSMutableArray alloc] init];
        // You can show users who match the uploaded unique keys on a list view.
        // Then the current user can decide to add them as friends or ignore them.
        for (SBDUser *user in friends) {
            [userIds addObject:user.userId];
        }

        // Adding new friends
        [SBDMain addFriendsWithUserIds:userIds completionHandler:^(NSArray<SBDUser *> * _Nullable users, SBDError * _Nullable error) {
            if (error != nil) { // Error.
                return;
            }
        }];
    }
}

@end
Light Color Skin
Copy
// ViewController.swift
class ViewController: UIViewController, SBDConnectionDelegate, SBDUserEventDelegate, SBDChannelDelegate {
    func initViewController() {
        // ...
        SBDMain.add(self as SBDUserEventDelegate, identifier: UNIQUE_DELEGATE_ID)
        // ...
    }

    func didDiscoverFriends(_ friends: [SBDUser]) {
        if friend != nil {
            var userIds:[String] = []
            // You can show users who match the uploaded unique keys on a list view.
            // Then the current user can decide to add them as friends or ignore them.
            for user in friends [] {
                userIds.append(user.userId)
            }

            // Adding new friends
            SBDMain.addFriends(withUserIds: userIds, completionHandler: { (users, error) in
                guard error == nil else {   // Error.
                    return
                }
            })
        }
    }
}

You can also allow the current user to delete existing friends by the deleteFriendsWithUserIds:completionHandler: method:

Objective-C
Swift
Light Color Skin
Copy
// Deleting existing friends
[SBDMain deleteFriendsWithUserIds:userIds completionHandler:^(SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
// Deleting existing friends
SBDMain.deleteFriends(withUserIds: userIds) { (error) in
    guard error == nil else {   // Error.
        return
    }
}

By using the SBDFriendListQuery's loadNextPageWithCompletionHandler: method, you can also retrieve a list of friends of the current user:

Objective-C
Swift
Light Color Skin
Copy
SBDFriendListQuery *friendListQuery = [SBDMain createFriendListQuery];
[friendListQuery loadNextPageWithCompletionHandler:^(NSArray<SBDUser *> * _Nullable users, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
let friendListQuery = SBDMain.createFriendListQuery()
friendListQuery?.loadNextPage(completionHandler: { (users, error) in
    guard error == nil else {   // Error.
        return
    }
})

Send typing indicators to other members

If the startTyping and endTyping methods are called when a user is typing a text message, SendBird server notifies of the event to the client apps of all channel members through the channelDidUpdateTypingStatus: of the registered channel delegate.

Objective-C
Swift
Light Color Skin
Copy
[groupChannel startTyping];
[groupChannel endTyping];
...

// To listen to an update from all the other channel members' client apps, implement the 'channelDidUpdateTypingStatus:' with things to do when notified.
@interface GroupChannelChattingViewController : ViewController<SBDChannelDelegate>

@end

@implementation GroupChannelChattingViewController

- (void)initGroupChannelChattingViewController {
    [SBDMain addChannelDelegate:self identifier:UNIQUE_DELEGATE_ID];
}

- (void)channelDidUpdateTypingStatus:(SBDGroupChannel * _Nonnull)sender {
    if ([sender.channelUrl isEqualToString:groupChannel.channelUrl]) {
        NSArray<SBDUser *> *members = [sender getTypingMembers];
        
        // Refresh typing status of members within the channel.
    }
}

@end
Light Color Skin
Copy
self.groupChannel.startTyping()
self.groupChannel.endTyping()
...

// To listen to an update from all the other channel members' client apps, implement the 'channelDidUpdateTypingStatus' with things to do when notified.
class GroupChannelChattingViewController: UIViewController, SBDChannelDelegate {
    SBDMain.add(self as SBDChannelDelegate, identifier: UNIQUE_DELEGATE_ID)

    func channelDidUpdateTypingStatus(_ sender: SBDGroupChannel) {
        if sender.channelUrl == self.groupChannel.channelUrl {
            let members = sender.getTypingMembers()
        
            // Refresh typing status of members within the channel.
        }
    }
}

Mark messages as read

To maintain the most up-to-date and accurate read status of messages for each member in a group channel, the markAsRead method should be called when any one of the members reads messages in the channel by entering the channel from a channel list or making the opened channel view in the background to be active on the screen.

When the markAsRead is called, SendBird server updates the number of the current user's unread messages both in a group channel and in all joined channels. The server then notifies the change of read status to all the other channel members' client apps through the channelDidUpdateReadReceipt: method of the channel event delegate.

Objective-C
Swift
Light Color Skin
Copy
// Call the 'markAsRead' when the current user views unread messages in a group channel.
[groupChannel markAsRead];
...

// To listen to an update from all the other channel members' client apps, implement the 'channelDidUpdateReadReceipt:' with things to do when notified.
@interface GroupChannelChattingViewController : ViewController<SBDChannelDelegate>

@end

@implementation GroupChannelChattingViewController

- (void)initGroupChannelChattingViewController {
    [SBDMain addChannelDelegate:self identifier:UNIQUE_DELEGATE_ID];
}

- (void)channelDidUpdateReadReceipt:(SBDGroupChannel * _Nonnull)sender {
    if ([currentGroupChannel.channelUrl isEqualToString:sender.channelUrl]) {
        // For example, code for redrawing a channel view.
    }
}

@end
Light Color Skin
Copy
// Call the 'markAsRead' when the current user views unread messages in a group channel.
groupChannel?.markAsRead()
...

// To listen to an update from all the other channel members' client apps, implement the 'channelDidUpdateReadReceipt' with things to do when notified.
class GroupChannelChattingViewController: UIViewController, SBDChannelDelegate {
    SBDMain.add(self as SBDChannelDelegate, identifier: UNIQUE_DELEGATE_ID)

    func channelDidUpdateReadReceipt(_ sender: SBDGroupChannel) {
        if currentGroupChannel?.channelUrl == sender.channelUrl {
            // For example, code for redrawing a channel view.
        }
    }
}

Retrieve members who have read a message

Using the getReadMembersWithMessage: method, you can retrieve members who have read a specifici message in a group channel. A list of the members for each message is depending on each member's read receipt.

To keep track of who have read a new message, we recommend implementing the getReadMembersWithMessage: in the channelDidUpdateReadReceipt: method. Then it will receive a callback from SendBird server when any other member has read a message. Afterwards you should pass the newly received message via the channelDidUpdateReadReceipt: to the getReadMembersWithMessage: as a parameter.

Objective-C
Swift
Light Color Skin
Copy
NSArray *readMembers = [groupChannel getReadMembersWithMessage:baseMessage];
Light Color Skin
Copy
let readMembers = self.groupChannel.getReadMembers(with: baseMessage)

The getReadMembersWithMessage: returns a list of members who have read a message except the current user and the message sender.

Note: Using the getUnreadMembersWithMessage: method, you can retrieve members who have not read a specific message except the current user and the message sender. And using the getReadStatus method, you can get a list of information on the read receipt of each member of the channel, except the current user. The read receipt indicates the timestamp of when each user has last read the messages in the channel, in Unix milliseconds.


Retrieve number of members who have not read a message

Using the getReadReciptOfMessage: method, you can retrieve the number of members who have not read a specific message in a group channel. To get the exact value, you should first update the channel by the markAsRead before calling the getReadReceiptOfMessage:.

Objective-C
Swift
Light Color Skin
Copy
// Call the 'markAsRead' when the current user views unread messages in a group channel.
[groupChannel markAsRead];
...

// To listen to an update from all the other channel members' client apps, implement the 'channelDidUpdateReadReceipt:' with things to do when notified.
@interface GroupChannelChattingViewController : ViewController<SBDChannelDelegate>

@end

@implementation GroupChannelChattingViewController

- (void)initGroupChannelChattingViewController {
    [SBDMain addChannelDelegate:self identifier:UNIQUE_DELEAGATE_ID];
}

- (void)channelDidUpdateReadReceipt:(SBDGroupChannel * _Nonnull)sender {
    if ([currentGroupChannel.channelUrl isEqualToString:sender.channelUrl]) {
        ...

        for (SBDBaseMessage *msg in messages) {
            int unreadCount = [sender getReadReceiptOfMessage:msg];
            if (unreadCount <= 0) {
                // All members have read the message.
            }
            else {
                // Some of members haven't read the message yet.            
            }
        }
    }
}

@end
Light Color Skin
Copy
// Call the 'markAsRead' when the current user views unread messages in a group channel.
groupChannel?.markAsRead()
...

// To listen to an update from all the other channel members' client apps, implement the 'channelDidUpdateReadReceipt' with things to do when notified.
class GroupChannelChattingViewController: UIViewController, SBDChannelDelegate {
    SBDMain.add(self as SBDChannelDelegate, identifier: UNIQUE_DELEGATE_ID)

    func channelDidUpdateReadReceipt(_ sender: SBDGroupChannel) {
        if currentGroupChannel?.channelUrl == sender.channelUrl {
            ...

            for msg in messages {
                let unreadCount = sender.getReadReceipt(of: msg)
                if unreadCount <= 0 {
                    // All members have read the message.
                }
                else {
                    // Some of members haven't read the message.
                }
            }
        }
    }
}

Retrieve the last message of a channel

You can retrieve the last message of a group channel.

Objective-C
Swift
Light Color Skin
Copy
SBDBaseMessage *lastMessage = groupChannel.lastMessage;
Light Color Skin
Copy
let lastMessage = groupChannel.lastMessage

Retrieve number of unread messages in a channel

You can retrieve the total number of the current user's unread messages in a group channel.

Objective-C
Swift
Light Color Skin
Copy
NSUInteger unreadMessageCount = groupChannel.unreadMessageCount;
Light Color Skin
Copy
let unreadMessageCount = groupChannel.unreadMessageCount

Retrieve number of unread messages in all channels

You can retrieve the total number of the current user's unread messages in all joined group channels.

Objective-C
Swift
Light Color Skin
Copy
[SBDMain getTotalUnreadMessageCountWithCompletionHandler:^(NSUInteger unreadCount, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
SBDMain.getTotalUnreadMessageCount { (totalUnreadMessageCount, error) in
    guard error == nil else {   // Error.
        return
    }
}

Retrieve number of channels with unread messages

You can retrieve the total number of the current user's joined group channels which one or more unread messages.

Objective-C
Swift
Light Color Skin
Copy
[SBDMain getTotalUnreadChannelCountWithCompletionHandler:^(NSUInteger unreadCount, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
SBDMain.getTotalUnreadChannelCount { (totalUnreadChannelCount, error) in
    guard error == nil else {   // Error.
        return
    }
}

Send an admin message

If you are using the Custom Plan, you can send admin messages to a group channel using the SendBird Dashboard or the Platform API. To send an admin message through your dashboard, go to the Application > Group channels panel, select a group channel, find the message box below, click the Admin Message tab, and then write your message in the box. An admin message is limited to 1,000 characters.

Unlike other types of messages, a push notification for an admin message is not available by default. If you want assistance on this, contact our sales team.

Note: For clients using the Free Plan, a suggesting message to upgrade to the Custom Plan will be returned when attempting to send an admin message using the Platform API.


Add extra data to a message

You have the option to create further actions in a channel by using extra data in a message. You can add one or more key-values items to a message which you can save, update, or remove, when necessary. Based on those items, you can design and implement several different actions such as measuring user engagement within a chosen time limit through polls or counting how many times a message has been copied by members.

Note: For the quality of performance, every SendBird application has its own limits to how many key-values items you can add to a single message, as well as the maximum number of values an item can have . If you would like more information on these limits, contact our engineering team.

Objective-C
Swift
Light Color Skin
Copy
// When a message has been successfully sent to a channel, create items with keys.
[groupChannel createMessageMetaArrayKeysWithMessage:MESSAGE keys:@[@"referees", @"games"] completionHandler:^(SBDBaseMessage * _Nullable message, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];

// Add values to specific items by their keys.
NSDictionary *valuesToAdd = @{
    @"referees": @[@"John", @"Brandon", @"Harry", @"Jay"],
    @"games": @[@"soccer", @"baseball", @"basketball"],
};

[groupChannel addMessageMetaArrayValuesWithMessage:MESSAGE keyValues:valuesToAdd completionHandler:^(SBDBaseMessage * _Nullable message, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];

// Remove existing values of specific items by their keys.
NSDictionary *valuesToRemove = @{
    @"referees": @[@"Brandon", @"Jay"],
};

[groupChannel removeMessageMetaArrayValuesWithMessage:MESSAGE keyValues:valuesToRemove completionHandler:^(SBDBaseMessage * _Nullable message, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];

// Delete items by their keys.
[groupChannel deleteMessageMetaArrayKeysWithMessage:MESSAGE keys:@[@"referees", @"games"] completionHandler:^(SBDBaseMessage * _Nullable message, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
// When a message has been successfully sent to a channel, creating items with keys.
groupChannel.createMessageMetaArrayKeys(withMessage: MESSAGE, keys: ["referees", "games"], completionHandler: { (message, error) in
    guard error == nil else {   // Error.
        return
    }
})

// Adding values to specific items by their keys.
let valuesToAdd = [
    "referees": ["John", "Brandon", "Harry", "Jay"],
    "games": ["soccer", "baseball", "basketball"]
]

groupChannel.addMessageMetaArrayValues(withMessage: MESSAGE, keyValues: valuesToAdd, completionHandler: { (message, error) in
    guard error == nil else {   // Error.
        return
    }
})

// Removing existing values of specific items by their keys.
let valuesToRemove = [
    "referees": ["Brandon", "Jay"]
]

groupChannel.removeMessageMetaArrayValues(with: MESSAGE, keyValues: valuesToRemove, completionHandler: { (message, error) in
    guard error == nil else {   // Error.
        return
    }
})

// Deleting items by their keys.
groupChannel.deleteMessageMetaArrayKeys(withMessage: MESSAGE, keys: ["referees", "games"], completionHandler: { (message, error) in
    guard error == nil else {   // Error.
        return
    }
})

To get the key-values items of a message, read the message.metaArrays.


Categorize channels by custom type

When creating a group channel, you can additionally specify a custom channel type for further channel grouping. This custom type takes on the form of a NSString, and can be handy in searching or filtering channels.

Note: The DATA and CUSTOM_TYPE are both NSString fields that allow you to append additional information to your channels. As mentioned above, a common use case for the CUSTOM_TYPE is to contain information for channel grouping (for example, categorizing School and Work channels). However, both these fields can be flexibly utilized.

Objective-C
Swift
Light Color Skin
Copy
NSMutableArray<NSString *> *users = [[NSMutableArray alloc] init];
[users addObject:@"Jed"];
[users addObject:@"Young"];

SBDGroupChannelParams *params = [[SBDGroupChannelParams alloc] init];
[params addUserIds:users];
[params setName:@"NAME"];
[params setCustomType:@"CUSTOM_TYPE"];
...

[SBDGroupChannel createChannelWithParams:params completionHandler:^(SBDGroupChannel * _Nullable groupChannel, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
var users: [String] = []
users.append("Jed")
users.append("Young")

var params = SBDGroupChannelParams()
params.addUserIds(users)
params.name = "NAME"
params.customType = "CUSTOM_TYPE"
...

SBDGroupChannel.createChannel(with: params) { (channel, error) in
    guard error == nil else {   // Error.
        return
    }
}

To get a channel's custom type, read the groupChannel.customType.


Categorize messages by custom type

When sending a message, you can additionally specify a custom message type for further message grouping. This custom type takes on the form of a NSString, and can be useful in searching or filtering messages.

Note: The DATA and CUSTOM_TYPE are both NSString fields that allow you to append additional information to your messages. As mentioned above, a common use case for the CUSTOM_TYPE is to contain information for message grouping (for example, categorizing Notes and Contacts messages). However, both these fields can be flexibly utilized.

To embed a custom type into a message, set a value of the type to a SBDUserMessageParams or SBDFileMessageParams object with other values, and pass the object as a parameter to the sendUserMessageWithParams:completionHandler: or sendFileMessageWithParams:completionHandler: method.

Objective-C
Swift
Light Color Skin
Copy
SBDUserMessageParams *params = [[SBDUserMessageParams alloc] init];
[params setMessage:MESSAGE];
[params setCustomType:CUSTOM_TYPE];
...

[groupChannel sendUserMessageWithParams:params completionHandler:^(SBDUserMessage * _Nullable userMessage, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
var params = SBDUserMessageParams()
params.message = MESSAGE
params.customType = CUSTOM_TYPE
...

groupChannel.sendUserMessage(with: params, completionHandler: { (userMessage, error) i
    guard error == nil else {   // Error.
        return
    }
})

To get a message's custom type, read the message.customType.


Search channels by name, URL, or other filters

You can search for specific group channels by adding keywords to a SBDGroupChannelListQuery instance. There are two types of keywords: a Name and a URL. The code sample below shows the query instance which returns a list of the current user's group channels that partially match the specified Name keyword in the names of the channels.

Objective-C
Swift
Light Color Skin
Copy
myChannelListQuery = [SBDGroupChannel createMyGroupChannelListQuery];
myChannelListQuery.includeEmptyChannel = YES;
[myChannelListQuery setChannelNameContainsFilter:@"SendBird"];
[myChannelListQuery loadNextPageWithCompletionHandler:^(NSArray<SBDGroupChannel *> * _Nullable groupChannels, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }

    // A list of group channels that partially match "SendBird" in their names is returned.
}];
Light Color Skin
Copy
myChannelListQuery = SBDGroupChannel.createMyGroupChannelListQuery()
myChannelListQuery?.includeEmptyChannel = true
myChannelListQuery?.setChannelNameContainsFilter("SendBird")
myChannelListQuery?.loadNextPage(completionHandler: { (groupChannels, error) in
    guard error == nil else {   // Error.
        return
    }

    // A list of group channels that partially match "SendBird" in their names is returned.
})

The following shows the query instance which returns a list of the current user's group channels that partially match the specified URL keyword in the URLs of the channels.

Objective-C
Swift
Light Color Skin
Copy
SBDGroupChannelListQuery *myChannelListQuery = [SBDGroupChannel createMyGroupChannelListQuery];
myChannelListQuery.includeEmptyChannel = YES;

NSMutableArray<NSString *> *channelUrls = [[NSMutableArray alloc] init];
[channelUrls addObject:@"seminar"];
[channelUrls addObject:@"lecture"];

[myChannelListQuery setChannelUrlsFilter:channelUrls];

[myChannelListQuery loadNextPageWithCompletionHandler:^(NSArray<SBDGroupChannel *> * _Nullable groupChannels, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
    
    // A list of group channels that partially match "seminar" or "lecture" in their names is returned.
}];
Light Color Skin
Copy
let myChannelListQuery = SBDGroupChannel.createMyGroupChannelListQuery()
myChannelListQuery?.includeEmptyChannel = true

var channelUrls: [String] = []
channelUrls.append("seminar")
channelUrls.append("lecture")

myChannelListQuery?.channelUrlsFilter = channelUrls

myChannelListQuery?.loadNextPage(completionHandler: { (groupChannels, error) in
    guard error == nil else {   // Error.
        return
    }
    
    // A list of group channels that partially match "seminar" or "lecture" in their names is returned.
})

The following table shows all the supported filters for SBDGroupChannelListQuery to search for group channels you want to retrieve. You can use any filters in a similar fashion with the sample code above.

NameFilters...

CustomTypesFilter

Group channels with the specified one or more custom types.

CustomTypeStartsWithFilter

Group channels with the custom type which starts with the specified value.

ChannelNameContainsFilter

Group channels that contain the specified value in their names.

ChannelUrlsFilter

Group channels with the specified one or more channel URLs.

SuperChannelFilter

Either super or nonsuper group channels.

PublicChannelFilter

Either public or private group channels.

UnreadChannelFilter

Group channels with one or more unread messages.

ChannelHiddenStateFilter

Group channels with the specified state and operating behavior.

MemberStateFilter

Group channels based on whether or not the user has accepted an invitation, or whether or not the user was invited by a friend.

UserIdsExactFilter

Group channels where the members with the specified one or more user IDs are exactly in.

UserIdsIncludeFilter

Group channels that include one or more members with the specified user IDs.

NicknameContainsFilter

Group channels with members whos nicknames contain the specified value.

MetaDataOrderKeyFilter

Group channels with metadata containing an item with the specified value as its key. This filter is effective only when the metadata are sorted in the alphabetical order.


Generate thumbnails of a file message

When sending an image file, you can determine whether to create thumbnails of the image, which you can fetch and render into your UI. You can specify up to 3 different dimensions to generate thumbnail images in, which can be useful for supporting various display densities.

Note: Supported file types are files whose media type is image/* or video/*. The SDK does not support creating thumbnails when sending a file message with a file URL.

The sendFileMessageWithParams:completionHandler: method requires that you pass a SBDFileMessageParams object as a parameter, containing a NSArray of SBDThumbnailSize objects which each specify the maximum values of width and height of a thumbnail image with the SBDThumbnailSize's makeWithMaxCGSize: or makeWithMaxWidth:maxHeight: constructors. The completionHandler: callback subsequently returns a NSArray of SBDThumbnail objects that each contain the URL of the generated thumbnail image file.

Objective-C
Swift
Light Color Skin
Copy
NSMutableArray<SBDThumbnailSize *> *thumbnailSizes = [[NSMutableArray alloc] init];

// Creating and adding a SBDThumbnailSize object (allowed number of thumbnail images: 3).
[thumbnailSizes addObject:[SBDThumbnailSize makeWithMaxCGSize:CGSizeMake(100.0, 100.0)]];
[thumbnailSizes addObject:[SBDThumbnailSize makeWithMaxWidth:200.0 maxHeight:200.0]];

SBDFileMessageParams *params = [[SBDFileMessageParams alloc] init];
...
[params setFile:FILE]; 
[params setFileName:FILE_NAME];
[params setFileSize:FILE_SIZE];
[params setMimeType:MIME_TYPE];
[params setThumbnailSizes:thumbnailSizes];  // Set a SBDThumbnailSize object to a SBDFileMessageParams object.

[groupChannel sendFileMessageWithParams:params completionHandler:^(SBDFileMessage * _Nonnull fileMessage, SBDError * _Nullable error) {
    if (error != nil) {     // Error.
        return;
    }

    SBDThumbnail *first = fileMessage.thumbnails[0];
    SBDThumbnail *second = fileMessage.thumbnails[1];

    CGSize maxSizeFirst = first.maxSize;    // 100
    CGSize maxSizeSecond = second.maxSize;  // 200

    NSString *urlFirst = first.url;
    NSString *urlSecond = second.url;
}];
Light Color Skin
Copy
var thumbnailSizes = [SBDThumbnailSize]()

// Creating and adding a SBDThumbnailSize object (allowed number of thumbnail images: 3).
thumbnailSizes.append(SBDThumbnailSize.make(withMaxCGSize: CGSize(width: 100.0, height: 100.0))!)
thumbnailSizes.append(SBDThumbnailSize.make(withMaxWidth: 200.0, maxHeight: 200.0)!)

var params = SBDFileMessageParams()
...
params.file = FILE 
params.fileName = FILE_NAME
params.fileSize = FILE_SIZE
params.mimeType = MIME_TYPE
params.thumbnailSizes = thumbnailSizes  // Set a SBDThumbnailSize object to a SBDFileMessageParams object.

groupChannel.sendFileMessage(with: params, completionHandler: { (fileMessage, error) in
    guard error == nil else {       // Error.
        return
    }

    let first = fileMessage?.thumbnails?[0]
    let second = fileMessage?.thumbnails?[1]

    let maxSizeFirst = first?.maxSize       // 100
    let maxSizeSecond = second?.maxSize     // 200

    let urlFirst = first?.url
    let urlSecond = second?.url
}

A thumbnail image is generated evenly to fit within the bounds of (maxWidth, maxHeight), which are provided through the constructor. Note that if the original image is smaller than the specified dimensions, the thumbnail isn't resized. The url returns the location of the generated thumbnail file within SendBird server.

This is one of SendBird's premium features, contact our sales team for further assistance.


Share an encrypted file with other members

This file encryption feature prevents users without access from opening and reading encrypted files that have been shared within a group of users. When this feature is turned on, all types of sent files and thumbnail images will be first uploaded to SendBird server, and then encrypted by AES256.

In a group channel, encrypted files and thumbnail images will be decrypted and accessed securely only by the members. Anyone outside of the channel and application will not have access to those files and thumbnail images. The following explains how this data security works and what to do at the SDK level to apply it to your client apps.

The SendBird system enables secure encryption and decryption of files by generating and distributing an opaque and unique encryption key for each user. An encryption key is managed internally by the system, and is valid for 3 days. It is generated every time the user logs in to SendBird server through the SDK, which then gets delivered to the SDK from the server.

When the SDK requests an encrypted file by its URL, the parameter auth should be added to the URL to access the file, which is specified with an encryption key of the user such as ?auth=RW5jb2RlIHaXMgdGV4eA==. With the specified key in the auth, SendBird server first decrypts the file, then checks if the user is a member of the group channel, and finally, allows the user to access and open the file in the channel.

This can be easily done by retrieving the fileMessage.url property, which returns the unique file URL containing the parameter auth with an encryption key of the current user.

This is one of SendBird's premium features, contact our sales team for further assistance. This feature will also require customized implementation efforts from your side.


Spam flood protection

This feature allows you to customize the number of messages a member can send in a group channel per second. By doing so, all excess messages will be deleted and only the number of messages allowed to be sent per member per second will be delivered. This feature protects your app from some members spamming others in the channel with the same messages.

Note: Our default system setting is 5 messages per second. This limit can be manually adjusted only from our side. You can contact our engineering team about this setting. This is one of SendBird's premium features, contact our sales team for further assistance.


Message auto-translation

It is possible for text messages to be sent in different languages through the SendBird's auto-translation feature. When sending a text message, set a NSArray of language codes to a SBDUserMessageParams object and then pass the object as a parameter to the sendUserMessageWithParams:completionHandler: method to request translated messages in the corresponding languages.

Note: This message auto-translation feature is powered by Google Cloud Translation API recognition engine and Microsoft Translator engine. It is by default that Google's Cloud Translation API recognition engine is used for message auto-translation, whereas if your SendBird application has been created before June 26, 2019, Microsoft Translator engine is used.

Objective-C
Swift
Light Color Skin
Copy
SBDUserMessageParams *params = [[SBDUserMessageParams alloc] init];
...
[params setTargetLanguages:@[@"es", @"ko"]];    // Spanish and Korean

[groupChannel sendUserMessageWithParams:params completionHandler:^(SBDUserMessage * _Nonnull userMessage, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
}];
Light Color Skin
Copy
var params = SBDUserMessageParams()
...
params.targetLanguages = ["es", "ko"]   // Spanish and Korean

groupChannel.sendUserMessage(with: params, completionHandler: { (userMessage, error) in
    guard error == nil else {   // Error.
        return
    }
})

You can retrieve translations of a text message using the userMessage.translations property which has a NSArray object containing the language codes and translations.

Note: The two translation engines support a wide variety of languages, and you can see their language code tables in the Miscellaneous > Language support section.

Objective-C
Swift
Light Color Skin
Copy
- (void)channel:(SBDBaseChannel * _Nonnull)sender didReceiveMessage:(SBDBaseMessage * _Nonnull)message {
    NSArray *translations = ((SBDUserMessage *)message).translations;
    NSString *esTranslatedMessage = translations[@"es"];    // Spanish
    ...
    // Display translation in UI.
}
Light Color Skin
Copy
func channel(_ sender: SBDBaseChannel, didReceive message: SBDBaseMessage) {
    let translations = (message as! SBDUserMessage).translations
    let esTranslatedMessage = translations["es"]    // Spanish
    ...
    // Display translation in UI.
}

Using the translateUserMessage:targetLanguages:completionHandler: method, you can also translate an already sent text message into other languages for your specific needs.

Objective-C
Swift
Light Color Skin
Copy
NSArray<NSString *> *targetLanguages = @[@"es", @"de"];     // Spanish and German

// The USER_MESSAGE below indicates a SBDUserMessage object which represents an already sent text message.
[groupChannel translateUserMessage:USER_MESSAGE targetLanguages:targetLanguages completionHandler:^(SBDUserMessage * _Nullable userMessage, SBDError * _Nullable error) {
    if (error != nil) { // Error.
        return;
    }
        
    NSArray *translations = ((SBDUserMessage *)userMessage).translations;
    NSString *esTranslatedMessage = translations[@"es"];    // Spanish
    NSString *deTranslatedMessage = translations[@"de"];    // German 
    ... 
    // TODO: Display translations in UI.
}];
Light Color Skin
Copy
let targetLanguages = ["es", "de"]

// The USER_MESSAGE below indicates a SBDUserMessage object which represents an already sent text message.
groupChannel.translateUserMessage(USER_MESSAGE, targetLanguages: targetLanguages, completionHandler: { (userMessage, error) in
    guard error == nil else {   // Error.
        return
    }

    let translations = (userMessage as! SBDUserMessage).translations
    let esTranslatedMessage = translations["es"] 
    let deTranslatedMessage = translations["de"]
    ... 
    // TODO: Display translations in UI.
})

Note: This is one of SendBird's premium features, contact our sales team for further assistance.