pragma mark----定时器

• (void)beginTimer {
  self.timer = [NSTimer scheduledTimerWithTimeInterval:60*60
  target:self
  selector:@selector(WeatherNotice)
  userInfo:nil
  repeats:YES];
  }

//开启定时器
[_timer setFireDate:[NSDate distantPast]];

//暂停定时器
[_timer setFireDate:[NSDate distantFuture]];

//取消定时器
[_timer invalidate];
_timer=nil;