@property(nonatomic,assign)int startMinute;//开始倒计时值
-(void)startTimer
{
_startMinute = 60;
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateUI) userInfo:nil repeats:YES];
//界面的其他操作不会导致定时器暂停
[[NSRunLoop currentRunLoop] addTimer:timer forMode:UITrackingRunLoopMode];
}
-(void)updateUI
{
_startMinute--;
_minuteLabel.text = [NSString stringWithFormat:@"%d",_startMinute];
}
