Message Delivery Status

For messages sent by the current user, the delivery status is shown in the message cell.

Delivery status can be one of the following:

• pending send (when a message is queued to be sent)
• sending failed (when message sending has failed)
• sent (when a message is sent but not yet seen by any channel member)
• read (when a message is seen by 1 or more channel members)

For group channels with more than 2 members, the number of members who have seen the message is shown next to the read indicator.

Pending send	Sending failed	Sent	Read	Read by many

Delivery Status Transitions

The diagram below shows how message delivery state changes.

Pending send

When user taps send button in message composer, the message is saved to local database and queued for sending. When it happens, message appears in the channel in pending send delivery status.

Pending send -> Sending failed

When message sending fails (for example because of missing Internet connection), a transition from pending send to sending failed state happens. In that case, delivery status gets hidden and error indicator appears.

Sending failed -> Pending send

If message sending has failed the long-pressing the message shows a pop-up with Resend action available. When user initiates message resend, the sending failed -> pending send transition happens.

Pending send -> Sent

When message sending succeeds, the state goes from pending send to sent and single checkmark appears. At this moment, channel members receive a web-socket event that the new message is posted to the channel which increments unread messages count for the channel.

Sent -> Read

When a channel member opens the channel / scrolls the channel to bottom and sees the message, the delivery state moves from sent -> read and double-checkmark is shown.

Another case is when a new member is added to the channel. When it happens, all messages in the channel get read by this member.

Read -> Sent

The transition happens when a message is read by a single channel member when this member is removed from the channel. In that case, message moves back to sent state.