Why Dispatch_group_notify works different in different environment?

The first situation is that I create a Command Line Tool Application,and run this code.

NSLog(@"Main:%@", [NSThread currentThread]);
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_group_t group = dispatch_group_create();


dispatch_group_async(group, queue, ^{ NSLog(@"Task1:%@", [NSThread currentThread]); });
dispatch_group_async(group, queue, ^{ NSLog(@"Task2:%@", [NSThread currentThread]); });


dispatch_group_notify(group, dispatch_get_main_queue(), ^{ NSLog(@"Finish:%@", [NSThread currentThread]); });

The log in terminal is

Main:<NSThread: 0x1028033b0>{number = 1, name = main}
Task2:<NSThread: 0x10040f0f0>{number = 2, name = (null)}
Task1:<NSThread: 0x1006008d0>{number = 3, name = (null)}

If I want to show last log in '

queue'

main queue'

dispatch_group_notify(group, dispatch_get_main_queue(), ^{ NSLog(@"Finish:%@", [NSThread currentThread]); });

with 'queue' :

dispatch_group_notify(group, queue, ^{ NSLog(@"Finish:%@", [NSThread currentThread]); });

The terminal print the last log.But why it can't revoke in Main queue?

When i copy this code to simple iOS Application(revoke block in main queue).All works well:

Main:<NSThread: 0x600000070ac0>{number = 1, name = main}
Task2:<NSThread: 0x6000002633c0>{number = 3, name = (null)}
Task1:<NSThread: 0x600000263480>{number = 4, name = (null)}
Finish:<NSThread: 0x600000070ac0>{number = 1, name = main}

And I try to add

sleep(1)

Why lead to these different?😕