MessagesDisplayDelegate

The MessagesDisplayDelegate protocol allows you to customize the general appearance of MessageCollectionViewCells, TextMessageCells, and their accompanying MessageHeaderView or MessageFooterView.

All of MessagesDisplayDelegate's methods have default implementations. You can override their behavior by providing your own implementation.

Customizing MessageCollectionViewCell

Customizing the messageContainerView's background color

    func backgroundColor(for message: MessageType, at  indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> UIColor

The default implementation of this method uses the isFromCurrentSender method of MessagesDataSource to evaluate if the message is from the current sender. It returns backgroundColor of light green if the message is from the current sender and light gray otherwise.

Customizing the messageContainerView's style

    func messageStyle(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> MessageStyle

This method allows you to customize the MessageStyle for the cell which is an enum containing the following 5 cases:

MessageStyle

public enum MessageStyle {
	case none
    case bubble
    case bubbleOutline(UIColor)
    case bubbleTail(TailCorner, TailStyle)
    case bubbleTailOutline(UIColor, TailCorner, TailStyle)
}

none Use this case if you want now style applied to the messageContainerView
bubble Use this case if you want message bubbles
bubbleOutline(UIColor) Use this case if you want message bubbles with an outline. The associated value UIColor is the color to use for the outline of the bubble.
bubbleTail(TailCorner, TailStyle) Use this case if you want message bubbles with a tail. You must specify the corner where the tail will be located and which tail style you'd like the bubble to have.
bubbleTailOutline(UIColor, TailCorner, TailStyle) Use this case if you want message bubbles with both a tail and outline. You must specify where the tail will be located and which tail style you'd like the bubble to have.

The default MessageStyle for a MessageCollectionViewCell is .bubble.

TailStyle

MessageKit currently supports 2 types of TailStyle:

public enum TailStyle {
	case curved
	case pointedEdge
}

The curved style is the type of tail that iMessage uses and the pointedEdge style is like Google Hangouts.

TailCorner

The TailCorner is just a simple enum representing the 4 corners of the messageContainerView:

public enum TailStyle {
	case topLeft
	case bottomRight
	case topRight
	case bottomRight
}

Customizing MessageHeaderView & MessageFooterView

Since MessageKit puts each MessageType in its own section in the MessagesCollectionView, this allows each message to have its own section MessageHeaderView and MessageFooterView. You can use the following 2 methods to provide custom section headers and footers for your messages:

    func messageHeaderView(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> MessageHeaderView?
    
    func messageFooterView(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> MessageFooterView?

By default, messageHeaderView uses the method shouldDisplayHeader(for:_:_) of MessagesDisplayDelegate to determine if it should return a MessageHeaderView subclass called MessageDateHeaderView or nil. The shouldDisplayHeader(for:_:_) method checks the showsDateHeaderAfterTimeInterval property of MessagesCollectionView and returns true if the the last message was sent after the specified time interval. The default value of this TimeInterval is 1 hour.

By default, messageFooterView returns nil.

Customizing a TextMessageCell's text color

    func textColor(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> UIColor

The default implementation of this method uses the isFromCurrentSender method of MessagesDataSource to evaluate if the message is from the current sender. It returns a text color of UIColor.white if the message is from the current sender and UIColor.darkText otherwise.

NOTE: This method only applies to TextMessageCell

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