I call method sr in viewDidLoad with below code,how can i cancel it before that method sr will call?
[self performSelector:@selector(sr) withObject:nil afterDela
[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(sr) object:nil];
Please read the documentation. :) The documentation for -performSelector:withObject:afterDelay: points you to the methods for canceling a queued perform request.