Testing asynchronous call in unit test in iOS

Question

I am facing a problem while unit testing an asynchronous call in iOS. (Although it is working fine in view controllers.)

Has anyone faced this issue before? I have t

Answer 1

You'll need to spin the runloop until your callback is invoked. Make sure that it gets invoked on the main queue, though.

Try this:

__block BOOL done = NO;
doSomethingAsynchronouslyWithBlock(^{
    done = YES;
});

while(!done) {
   [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
}

You can also use a semaphore (example below), but I prefer to spin the runloop to allow asynchronous blocks dispatched to the main queue to be processed.

dispatch_semaphore_t sem = dispatch_semaphore_create(0);
doSomethingAsynchronouslyWithBlock(^{
    //...
    dispatch_semaphore_signal(sem);
});

dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);