How to pause time in iOS Programming

In 开发者_如何转开发my iOS program, I want a function to pause for 1 second. What code do I have to write to do this?

You can use one of these: sleep(1); or wait(1);

Or you can use [NSThread sleepForTimeInterval:1.0]

And there is also performSelector:withObject:afterDelay

Another way to do this is:

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{//Place code here});

sleep() and wait() are sometimes looked down upon but as long as you understand whats happening use it at your free will

Newer to iOS are completion blocks. If you need to perform some action after a view controller is popped, for example, you could now use blocks. I recently used this method to dismiss a message compose view controller and then pop the current view controller if successful.

Old way:

[controller dismissModalViewControllerAnimated:YES];
// Use an NSThread or performSelector:withObject:afterDelay

New Way:

[controller dismissViewControllerAnimated:YES completion:^{
  if (result != MessageComposeResultCancelled){
    // If cancelled remain on current screen, else pop to parent view controller
    [self.navigationController popViewControllerAnimated:YES];
  }
}];