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定义一个全局时间变量
NSTimer *_timer;
创建时间变量 并调用定时器方法
- (void)viewDidLoad
{
[super viewDidLoad];
_timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timeClick) userInfo:nil repeats:YES];
[_timer fireDate];//启动定时器
#pragma mark - 考试时间倒计时
- (void)timeClick
{
timeout -= 1;
NSInteger hour = timeout / 3600;
NSInteger minutes = (timeout / 60) % 60;
NSInteger seconds = timeout % 60;
NSString *strTime = [NSString stringWithFormat:@"%.2ld:%.2ld:%.2ld",(long)hour,(long)minutes, (long)seconds];
[rightButton setTitle:strTime forState:UIControlStateNormal];
if (timeout <= 0)
{
[_timer setFireDate:[NSDate distantFuture]];
[self showAlertView:@"考试时间已到"];
}
}
if (_isClick)
{//开始
if ([_timer isValid])
{
[_timer invalidate];
_timer = nil;
label.text = @"开始";
_isClick = NO;
}
}
else
{//暂停
//invalidate后再重新创建时间, 由于属性保存了保值, 所以计数器从属性值开始计数
_timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timeClick) userInfo:nil repeats:YES];
[_timer fireDate];
label.text = @"暂停";
_isClick = YES;
}
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原文地址：http://www.cnblogs.com/balopy/p/4826865.html
