# Core features

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The Video SDK for iOS provides in-session text chat: users can send public and private messages to everyone or to a specific user, and your app receives a callback as each message arrives. Use the `ZoomVideoSDKChatHelper` to send messages and implement `onChatNewMessageNotify` on your `ZoomVideoSDKDelegate` to receive them.

To transfer files through chat, see [Send files in chat](/docs/video-sdk/ios/chat/send-files-in-chat/). To read message metadata, delete messages, or apply host chat privileges, see [Manage chat messages](/docs/video-sdk/ios/chat/chat-message-details/).

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.

> Common chat implementations in iOS use `UITableView` to display messages. The following sections focus on the SDK chat API only. See [UITableView in iOS](https://developer.apple.com/documentation/uikit/uitableview) for the UI side.

## Get the chat helper

To send messages or change privileges, grab the `ZoomVideoSDKChatHelper` from the SDK singleton. Every chat call hangs off it.

```swift
let chatHelper = ZoomVideoSDK.shareInstance()?.getChatHelper()
```

```objectivec
ZoomVideoSDKChatHelper *chatHelper = [[ZoomVideoSDK shareInstance] getChatHelper];
```

## Send a public message

Before exposing a chat composer in your UI, check that chat is enabled. The host may have disabled it for the session through [chat privileges](/docs/video-sdk/ios/chat/chat-message-details/#host-control-chat-privileges). The send methods return a `ZoomVideoSDKError`; check it for `Errors_Success` to confirm the SDK accepted the message.

```swift
if let chatHelper = ZoomVideoSDK.shareInstance()?.getChatHelper() {
    // Check whether chat is enabled in this session.
    if !chatHelper.isChatDisabled() {
        let error = chatHelper.sendChat(toAll: message)
        if error == .Errors_Success {
            // The SDK accepted the message.
        }
    }
}
```

```objectivec
ZoomVideoSDKChatHelper *chatHelper = [[ZoomVideoSDK shareInstance] getChatHelper];
// Check whether chat is enabled in this session.
if (chatHelper.IsChatDisabled == NO) {
    ZoomVideoSDKError error = [chatHelper SendChatToAll:message];
    if (error == Errors_Success) {
        // The SDK accepted the message.
    }
}
```

## Send a private message

Private messages are also a chat privilege the host can disable, separately from public chat. Check `isPrivateChatDisabled` before exposing a "send to user" UI.

```swift
if let chatHelper = ZoomVideoSDK.shareInstance()?.getChatHelper() {
    // Check whether public and private chat are enabled in this session.
    if !chatHelper.isChatDisabled(), !chatHelper.isPrivateChatDisabled() {
        let error = chatHelper.sendChat(to: user, content: message)
        if error == .Errors_Success {
            // The SDK accepted the message.
        }
    }
}
```

```objectivec
ZoomVideoSDKChatHelper *chatHelper = [[ZoomVideoSDK shareInstance] getChatHelper];
// Check whether public and private chat are enabled in this session.
if (chatHelper.IsChatDisabled == NO && chatHelper.IsPrivateChatDisabled == NO) {
    ZoomVideoSDKError error = [chatHelper SendChatToUser:user Content:message];
    if (error == Errors_Success) {
        // The SDK accepted the message.
    }
}
```

## Receive incoming messages

Implement `onChatNewMessageNotify` on your `ZoomVideoSDKDelegate`. The callback fires for both messages you receive _and_ messages you send. The `chatMessage` parameter contains the message content and a `ZoomVideoSDKUser` for both the sender and recipient.

```swift
func onChatNewMessageNotify(_ helper: ZoomVideoSDKChatHelper?, message chatMessage: ZoomVideoSDKChatMessage?) {
    if let content = chatMessage?.content, let senderName = chatMessage?.senderUser?.getName() {
        print("\\(senderName) sent a message: \\(content)")
    }
}
```

```objectivec
- (void)onChatNewMessageNotify:(ZoomVideoSDKChatHelper *)helper message:(ZoomVideoSDKChatMessage *)chatMessage {
    NSString *content = chatMessage.content;
    ZoomVideoSDKUser *sender = chatMessage.senderUser;
    NSLog(@"%@ sent a message: %@", sender.getUserName, content);
}
```

For everything else you can read off a `ZoomVideoSDKChatMessage` (timestamps, recipients, message ID, public-vs-private flag), see [Manage chat messages](/docs/video-sdk/ios/chat/chat-message-details/).