To keep the most up-to-date and accurate read status of messages for all group channel members, the
markAsRead() method should be called every time one of the members reads messages by entering the channel from a channel list or bringing the chat view to the foreground.
If the current user opens a channel and
markAsReadAll() is called, the Sendbird server will update both the unread message count of the individual channel and the total unread message count of all the group channels joined by the user. The server then notifies the change of read status to all members' devices through the
onUnreadMemberCountUpdated() method in the channel event handler, except the one that is being used by the current user.
When a channel member sends a message to the channel, the Sendbird server updates the member's read receipt to the time when the message has sent. Meanwhile, the read receipts of other channel members can be updated when the
markAsRead() method is called. If a new member joins the channel, the method works differently based on the value of the
display_past_message property of your Sendbird application. If the property is set to
true, the new member’s read receipt will be updated to the sent time of the last message in the channel. If set to
false, it will be
display_past_messageproperty determines whether to display past messages to newly joined members when they enter the channel. This property is also linked to the
Chat historyoption, which can be adjusted on Sendbird Dashboard under Settings > Chat > Channels > Group channels.