Leave A Group

Guide to leaving groups using the CometChat iOS SDK leaveGroup method to stop receiving group messages.

Quick Reference for AI Agents & Developers

• Leave group: CometChat.leaveGroup(GUID:onSuccess:onError:)
• Note: Group owner cannot leave — must transfer ownership first
• Related: Join Group · Transfer Ownership · Groups Overview

Leave a Group

In order to stop receiving updates and messages for any particular joined group, you will have to leave the group using the leaveGroup() method.

Leave Group Parameters

Parameter	Type	Description
GUID	String	Unique group identifier to leave

Swift

let guid = "cometchat-guid-11"

CometChat.leaveGroup(GUID: guid, onSuccess: { (response) in
    print("Left group successfully.")
}, onError: { (error) in
    print("Group leaving failed with error:" + error!.errorDescription)
})

Objective C

NSString *guid = @"cometchat-guid-101";

[CometChat leaveGroupWithGUID:guid onSuccess:^(NSString * response) {
    NSLog(@"Left group successfully. %@", response);
} onError:^(CometChatException * error) {
    NSLog(@"Group leaving failed with error: %@", [error errorDescription]);
}];

Sample Payload - Leave Group

Request Parameters:

Parameter	Type	Description
GUID	String	Unique group identifier to leave. Example: "cometchat-guid-1"

Success Response:

Parameter	Type	Description
response	String	Success message. Example: "Group left successfully."

After Leaving Group:

Effect	Description
Messages	User will NOT receive messages from this group
Member List	User will NOT appear in group member list
hasJoined	Will be false if group is fetched again
Rejoin	User can rejoin if group is public or password-protected

Error Response (CometChatException):

Parameter	Type	Description
errorCode	String	Unique error code. Example: "ERR_GROUP_NOT_JOINED"
errorDescription	String	Human-readable error message. Example: "The user with UID cometchat-uid-2 is not a member of the group with GUID cometchat-guid-1. Please join the group to access it."

Sample Payload - Leave Group (Owner Error)

Request Parameters:

Parameter	Type	Description
GUID	String	Unique group identifier to leave. Example: "cometchat-guid-1"

Error Response:

Parameter	Type	Description
errorCode	String	Unique error code. Example: "ERR_OWNER_CANNOT_LEAVE"
errorDescription	String	Human-readable error message. Example: "Group owner cannot leave - must transfer ownership first"

Group owner CANNOT leave the group. Owner must transfer ownership first using transferGroupOwnership().

Once a group is left, the user will not receive any updates or messages pertaining to the group.

Group owner CANNOT leave the group. Owner must transfer ownership first using transferGroupOwnership().

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Real-time Leave Group Event

In other words, as a member of a group, how do I know if someone has left it?

If a user leaves any group, the members of the group receive a real-time event in the onGroupMemberLeft() method of the CometChatGroupDelegate. In order to receive user Events, you must add protocol conformance CometChatGroupDelegate as shown below:

Swift

class ViewController: UIViewController, CometChatGroupDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        CometChat.groupdelegate = self
    }
    
    func onGroupMemberLeft(action: ActionMessage, leftUser: User, leftGroup: Group) {
        print("\(leftUser.name ?? "") left the group \(leftGroup.name ?? "").")
    }
}

Objective C

@interface ViewController ()<CometChatGroupDelegate>
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [CometChat setGroupdelegate:self];
}

- (void)onGroupMemberLeftWithAction:(ActionMessage *)action leftUser:(User *)leftUser leftGroup:(Group *)leftGroup {
    // User left the group
}

@end

Sample Payload - onGroupMemberLeft Event

Event Trigger: Received via CometChatGroupDelegate.onGroupMemberLeft(action:leftUser:leftGroup:)

ActionMessage Object:

Parameter	Type	Description
action	String	Action type. Example: "left"
actionBy	User	User who performed the action. Example: {"uid": "user123", "name": "John"}
actionFor	Group	Group where action occurred. Example: {"guid": "group123", "name": "My Group"}

leftUser (User Object):

Parameter	Type	Description
uid	String?	Unique identifier of the user who left. Example: "user123"
name	String?	Display name of the user. Example: "John Doe"
avatar	String?	URL to the user’s avatar image. Example: "https://example.com/avatar.png"
status	UserStatus	Current online status. Example: .online

leftGroup (Group Object):

Parameter	Type	Description
guid	String	Unique group identifier. Example: "group123"
name	String?	Group display name. Example: "My Group"
membersCount	Int	Updated member count (decremented). Example: 14

Do not forget to set your view controller as a CometChat delegate probably in viewDidLoad() as CometChat.groupdelegate = self

Missed Group Member Left Events

In other words, as a member of a group, how do I know if someone has left it when my app is not running?

When you retrieve the list of previous messages if a member has left any group that the logged-in user is a member of, the list of messages will contain an Action message. An Action message is a sub-class of BaseMessage class.

For the group member left event, in the Action object received, the following fields can help you get the relevant information:

Field	Value	Description
action	"left"	Action type
actionBy	User object	User who left the group
actionFor	Group object	Group the user left

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CometChatGroupDelegate

Listen for real-time group events by conforming to CometChatGroupDelegate.

Delegate Methods

Method	Parameters	Description
onMemberAddedToGroup	action, addedBy, addedUser, addedTo	Member added
onGroupMemberLeft	action, leftUser, leftGroup	Member left
onGroupMemberJoined	action, joinedUser, joinedGroup	Member joined
onGroupMemberKicked	action, kickedUser, kickedBy, kickedFrom	Member kicked
onGroupMemberBanned	action, bannedUser, bannedBy, bannedFrom	Member banned
onGroupMemberUnbanned	action, unbannedUser, unbannedBy, unbannedFrom	Member unbanned
onGroupMemberScopeChanged	action, updatedUser, scopeChangedTo, scopeChangedFrom, group	Scope changed
onOwnershipChanged	group, newOwner	Owner changed

Sample Payload - Start Listening for Group Events

Setup Configuration:

Parameter	Type	Description
groupdelegate	CometChatGroupDelegate	Reference to the delegate object. Example: self

Listening Status:

Parameter	Type	Description
status	String	Current listening state. Example: "Listening for group events"

Events Being Monitored:

Event	Description
onMemberAddedToGroup	When member is added
onGroupMemberLeft	When member leaves
onGroupMemberJoined	When member joins
onGroupMemberKicked	When member is kicked
onGroupMemberBanned	When member is banned
onGroupMemberUnbanned	When member is unbanned
onGroupMemberScopeChanged	When scope changes
onOwnershipChanged	When ownership transfers

Sample Payload - Stop Listening for Group Events

Cleanup Configuration:

Parameter	Type	Description
groupdelegate	CometChatGroupDelegate?	Set to nil to stop receiving events. Example: nil

Listening Status:

Parameter	Type	Description
status	String	Current listening state. Example: "No longer listening for group events"

• Set delegate in viewDidLoad(): CometChat.groupdelegate = self
• Remove delegate when view is dismissed to avoid memory leaks

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Common Error Codes

Error Code	Description	Resolution
ERR_NOT_LOGGED_IN	User is not logged in	Login first using CometChat.login()
ERR_GUID_NOT_FOUND	Group does not exist	Verify the GUID is correct
ERR_GROUP_NOT_JOINED	Not a member of this group	User must be a member to leave
ERR_OWNER_CANNOT_LEAVE	Owner cannot leave group	Transfer ownership first using transferGroupOwnership()