NSTimer

//NSTimer如果不添加到NSRunLoopCommonModes 在滑动的时候就会停止工作
- (void)timer
{
    NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self selector:@selector(run) userInfo:nil repeats:YES];
    // 定时器只运行在NSDefaultRunLoopMode下，一旦RunLoop进入其他模式，这个定时器就不会工作
    //    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];

    // 定时器只运行在UITrackingRunLoopMode下，一旦RunLoop进入其他模式，这个定时器就不会工作
    //    [[NSRunLoop currentRunLoop] addTimer:timer forMode:UITrackingRunLoopMode];

    // 定时器会跑在标记为common modes的模式下
    // 标记为common modes的模式：UITrackingRunLoopMode和NSDefaultRunLoopMode
    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
}

修改Mode

[[NSRunLoop currentRunLoop] runMode:NSRunLoopCommonModes beforeDate:[NSDate distantFuture]];

主线程添加NSTimer

- (void)timer2
{
    // 调用了scheduledTimer返回的定时器，已经自动被添加到当前runLoop中，而且是NSDefaultRunLoopMode
    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(run) userInfo:nil repeats:YES];

    // 修改模式
    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
}

子线程添加NSTimer

- (void)viewDidLoad {
    [super viewDidLoad];

    self.thread = [[XMGThread alloc] initWithTarget:self selector:@selector(execute) object:nil];
    [self.thread start];
}


- (void)execute
{
    //scheduledTimerWithTimeInterval相当于下面这两句代码
    [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(test) userInfo:nil repeats:YES];

    [[NSRunLoop currentRunLoop] run];
}

===========================================
-(void)execute
{
    NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self selector:@selector(test) userInfo:nil repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];

    [[NSRunLoop currentRunLoop] run];
}