NSTimer *newsTimes = [NSTimer scheduledTimerWithTimeInterval:4 target:self selector:@selector(displayNews) userInfo:nil repeats:YES];//设置 4 秒中循环执行 displayNews 方法
//取消定时器(永久停止)
[newsTimes invalidate];
newsTimes = nil;
//关闭(暂停、暂时关闭)
[newsTimes setFireDate:[NSDate distantFuture]];
//启动
[newsTimes setFireDate:[NSDate distantPast]];
NSTimer *myTimer = [NSTimer timerWithTimeInterval:3.0 target:self selector:@selector(timerFired) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:_myTimer forMode:NSDefaultRunLoopMode];