[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timeaction:) userInfo:@"liyang" repeats:NO]; NSTimer *tt= [NSTimer timerWithTimeInterval:1 target:self selector:@selector(timeaction:) userInfo:@"limengxia" repeats:NO]; [[NSRunLoop currentRunLoop]addTimer:tt forMode:NSDefaultRunLoopMode]; [[NSRunLoop currentRunLoop]run]; //NSRunLoop的理解,每一个线程都有一个NSRunLoop对象,然而定时器也是在这个对象上面运行的,当一个线程运行完成了过后,会自动关闭线程,自然NSRunLoop也会被销毁,自然定时器就不会运行,为了不让其线程关闭,用此语句 [[NSRunLoop currentRunLoop]run];那么线程就会保持活跃状态,不会被关闭,自然定时器也就能用了,[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timeaction:) userInfo:@"liyang" repeats:NO];这么设置的定时器是自动添加到了NSRunLoop中的, NSTimer *tt= [NSTimer timerWithTimeInterval:1 target:self selector:@selector(timeaction:) userInfo:@"limengxia" repeats:NO];这个定时器需要手动添加 [[NSRunLoop currentRunLoop]addTimer:tt forMode:NSDefaultRunLoopMode];