学步园

//延迟执行

[self performSelector:@selector(hidenSelf) withObject:nil afterDelay:2];

//取消延迟执行

[[self class] cancelPreviousPerformRequestsWithTarget:self selector:@selector(hidenSelf) object:nil];

访问官网：https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSObject_Class/Reference/Reference.html

Sending Messages

• – performSelector:withObject:afterDelay:
  
• – performSelector:withObject:afterDelay:inModes:
  
• – performSelectorOnMainThread:withObject:waitUntilDone:
  
• – performSelectorOnMainThread:withObject:waitUntilDone:modes:
  
• – performSelector:onThread:withObject:waitUntilDone:
  
• – performSelector:onThread:withObject:waitUntilDone:modes:
  
• – performSelectorInBackground:withObject:
  
• + cancelPreviousPerformRequestsWithTarget:
  
• + cancelPreviousPerformRequestsWithTarget:selector:object:

下面给出一个例子：

- (IBAction)Start:(id)sender {
    [self performSelector:@selector(doSomething:)];
    //[self doSomething:nil];
    //[self per
    [self performSelectorInBackground:@selector(doSomething:) withObject:nil];
   
}
-(void)doSomething:(id)inputData
{
    if([NSThread isMainThread])
    {
        NSLog(@"in main thread");
       
    }
    else {
        NSLog(@"not in main thread");
    }
    NSLog(@"kkkkk");
}