# Chat

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Chat is is designed to support in-session text communication. Zoom truncates messages exceeding a binary size of 10,000 bytes. As a best practice, we recommend a limit of 1000 characters per message.

While in a session, users can send chat messages to each other.

The following two main components within the SDK will help you implement in-session messaging features:

-   An instance of `ZMVideoSDKChatHelper` provides methods that can be used to send and receive messages in a session running on your app.
-   The `onChatNewMessageNotify` callback from your `ZMVideoSDKDelegate` confirms the delivery of a message.

## Send chat messages

Users can send a message privately to a single user or publicly to the entire session.

### Send a private chat message

```swift
// Get the ZMVideoSDKChatHelper to perform chat actions.
if let chatHelper = ZMVideoSDK.shared()?.getChatHelper() {
    // Check if chat is enabled in this session.
    if chatHelper.isChatDisabled() == false, chatHelper.isPrivateChatDisabled() == false {
        // Send message to User.
        chatHelper.sendChat(to: user, content: message)
    }
}
```

```objectivec
// Get the ZMVideoSDKChatHelper to perform chat actions.
ZMVideoSDKChatHelper *chatHelper = [[ZMVideoSDK sharedZMVideoSDK] getChatHelper];
// Check if chat is enabled in this session.
if ([chatHelper IsChatDisabled] == NO && [chatHelper IsPrivateChatDisabled] == NO) {
    // Send message to User.
    [chatHelper SendChatToUser:user Content:message];
}
```

### Send a public chat message to all users in a session

```swift
// Get the ZMVideoSDKChatHelper to perform chat actions.
if let chatHelper = ZMVideoSDK.shared()?.getChatHelper() {
    // Check if chat is enabled in this session.
    if chatHelper.isChatDisabled() == false{
        // Send message to all users in this session.
        chatHelper.sendChat(toAll: message)
    }
}
```

```objectivec
// Get the ZMVideoSDKChatHelper to perform chat actions.
ZMVideoSDKChatHelper *chatHelper = [[ZMVideoSDK sharedZMVideoSDK] getChatHelper];
// Check if chat is enabled in this session.
if ([chatHelper IsChatDisabled] == NO) {
    // Send message to all users in this session.
    [chatHelper SendChatToAll:message];
}
```

## Receive chat messages

To be notified when a message is received use `onChatNewMessageNotify` within `ZMVideoSDKDelegate`. The parameter `chatMessage` contains information about the message including an `ZMVideoSDKUser` info object for both the sender and recipient (if applicable).

```swift
func onChatNewMessageNotify(_ helper: ZMVideoSDKChatHelper!, message chatMessage: ZMVideoSDKChatMessage!) {
    // Use helper to perform chat actions.
    // Message contains the info about a chat message.
    if let content = chatMessage.content, let senderName = chatMessage.sendUser.getName() {
        print("\(senderName) sent a message: \(content)")
    }
}
```

```objectivec
- (void)onChatNewMessageNotify:(ZMVideoSDKChatHelper *)helper message:(ZMVideoSDKChatMessage *)chatMessage {
    // Use helper to perform chat actions.
    // Message contains the info about a chat message.
    NSString *content = chatMessage.content;
    VideoSDKUser *sender = chatMessage.sendUser;
    NSLog(@"%@ sent a message: %@", [sender getName], content);
}
```

For more information on how to use the `ZMVideoSDKUser` object, see [Sessions](/docs/video-sdk/macos/sessions/).

## Chat message details

Here are some additional considerations to make note of while using `ZMVideoSDKChatMessage`:

```swift
let isChatToAll = chatMessage.isChatToAll // Returns false for private messages.
let currentUserIsSender = chatMessage.isSelfSend // Returns true if the current user sent the message.
let timeMessageWasSent = chatMessage.timeStamp // The time at which the message was sent.
let recipient = chatMessage.receiverUser // The recipient of a private message.
```

```objectivec
chatMessage.isChatToAll; // Returns false for private messages.
chatMessage.isSelfSend; // Returns true if the current user sent the message.
chatMessage.timeStamp; // The time at which the message was sent.
chatMessage.receiverUser; // The recipient of a private message.
```

## Callbacks

The following is an example of a chat callback.

### Get notified when a message is delivered

```swift
func onChatNewMessageNotify(_ chatHelper: ZMVideoSDKChatHelper!, chatMessage: ZMVideoSDKChatMessage!) {
    // Use helper to perform chat actions.
    // Message contains the info about a chat message.
    if let content = chatMessage.content, let senderName = chatMessage.sendUser.getName() {
        print("\(senderName) sent a message: \(content)")
    }
}
```

```objectivec
- (void)onChatNewMessageNotify:(ZMVideoSDKChatHelper*)chatHelper chatMessage:(ZMVideoSDKChatMessage*)chatMessage {
    // Use helper to perform chat actions.
    // Message contains the info about a chat message.
    NSString *content = chatMessage.content;
    ZMVideoSDKUser *sender = [chatMessage getSendUser];
    NSLog(@"%@ sent a message: %@", sender.getUserName, content);
}
```

## Send files in chat

Users can transfer files in chat during the session.

> Zoom deletes files sent via in-session chat when the session ends.

Enable [send files via in-session chat](/docs/build/account/#in-session-advanced) in your Video SDK account portal settings and configure the following settings.

-   **Only allow specified file types** - Select to allow only specific file types and enter the file extensions in the text box, separated by commas.
-   **Maximum file size** - Select to limit the file size to 2048 MB.

Check if the file transfer feature is enabled.

```swift
let ret = ZMVideoSDK.shared().getSessionInfo().isFileTransferEnabled()
```

```objectivec
BOOL ret =  [[[ZMVideoSDK sharedVideoSDK] getSessionInfo] isFileTransferEnabled];
```

Get the list of allowed file types that you can transfer.

```swift
let ret = ZMVideoSDK.shared().getSessionInfo().getTransferFileTypeWhiteList()
```

```objectivec
NSString *ret =  [[[ZMVideoSDK sharedVideoSDK] getSessionInfo] getTransferFileTypeWhiteList];
```

Get the maximum file size to transfer.

```swift
let ret = ZMVideoSDK.shared().getSessionInfo().getMaxTransferFileSize()
```

```objectivec
unsigned long long  ret =  [[[ZMVideoSDK sharedVideoSDK] getSessionInfo] getMaxTransferFileSize];
```

Send files to all users in the current session.

```swift
let ret = ZMVideoSDK.shared().getSessionInfo().transferFile(filePath: String)
```

```objectivec
ZMVideoSDKErrors ret =  [[[ZMVideoSDK sharedVideoSDK] getSessionInfo] transferFile:self.filePathTextF.stringValue];
```

Send files to a certain user in the session.

```swift
// Locate the user that you will like to send the file to
let receiver: ZMVideoSDKUser

// Send file directly
let ret = receiver.transferFile(filePath: String)

```

```objectivec
ZMVideoSDKErrors ret =  [_receiverUser transferFile:self.filePathTextF.stringValue];
```

Cancel sending files.

```swift
// getCurrentSendFileObj is a user-defined method, to retrieve the sending file.
let sendFile: ZMVideoSDKSendFile = getCurrentSendFileObj()
let ret = sendFile.cancelSend()
```

```objectivec
ZMVideoSDKSendFile *send = [self getCurrentSendFileObj]; // getCurrentSendFileObj is a user-defined method, to retrieve the sending file.
ZMVideoSDKErrors ret =  [send cancelSend];
```

Start receiving files.

```swift
// getCurrentReceiveFileObj is a user-defined method, to retrieve the receiving file.
let receiveFile: ZMVideoSDKReceiveFile = getCurrentReceiveFileObj()

let fileDomain = FileManager.default.urls(for: .downloadsDirectory, in: .userDomainMask).map(\.path).last
let filePath = "<File path to receive>"
let downloadFilePath = "\(fileDomain)/\(filePath.count > 0 ? filePath : receiveFile.fileName)"

if (receiveFile) {
  let ret = receiveFile.startReceive(downloadFilePath)
  }
```

```objectivec
ZMVideoSDKReceiveFile *receive = [self getCurrentReceiveFileObj]; //getCurrentReceiveFileObj is a user-defined method, to retrieve the receiving  file.

NSString *fileDomain = [NSSearchPathForDirectoriesInDomains(NSDownloadsDirectory, NSUserDomainMask, YES).lastObject copy];
NSString *filePath = @"<File path to receive>";
NSString *downloadFilePath = [NSString stringWithFormat:@"%@/%@",fileDomain,filePath.length>0?filePath:receive.fileName];

if (receive) {
  ZMVideoSDKErrors ret =  [receive startReceive:downloadFilePath];
  } else {
    NSLog(@"receive is null");
  }
```

Cancel receiving files.

```swift
// getCurrentReceiveFileObj is a user-defined method, to retrieve the receiving file.
let receiveFile: ZMVideoSDKReceiveFile = getCurrentReceiveFileObj()

let downloadPath = FileManager.default.urls(for: .downloadsDirectory, in: .userDomainMask).map(\.path).last
if (receiveFile) {
  let ret = receiveFile.cancelReceive()
  }
```

```objectivec
ZMVideoSDKReceiveFile *receive = [self getCurrentReceiveFileObj]; // getCurrentReceiveFileObj is a user-defined method, to retrieve the receiving  file.
  if (receive) {
    ZMVideoSDKErrors ret =  [receive cancelReceive];
  } else {
    NSLog(@"receive is null");
  }
```

### File transfer callbacks

Be sure that you have [set up a delegate for callback events](/docs/video-sdk/macos/integrate/#implement-a-delegate) to receive file transfer callbacks.

Get notified when you transfer a file.

```swift
func onSendFile(_ sendFile: ZMVideoSDKSendFile!, status: ZMVideoSDKFileTransferStatus) {
  // Get the transfer status of the file and the file content here.
  }
```

```objectivec
- (void)onSendFile:(ZMVideoSDKSendFile *)sendFile status:(ZMVideoSDKFileTransferStatus)status
{
  // Get the transfer status of the file and the file content here.
}

```

Get notified when you receive a file from other users.

```swift
func onReceiveFile(_ receiveFile: ZMVideoSDKReceiveFile!, status: ZMVideoSDKFileTransferStatus) {
  // Get the transfer status of the file and the file content here.
  }
```

```objectivec
-(void)onReceiveFile:(ZMVideoSDKReceiveFile *)receiveFile status:(ZMVideoSDKFileTransferStatus)status
{
  // Get the transfer status of the file and the file content here.
}
```