ios 倒计时 （离开界面再回来继续）

ios 倒计时 （离开界面再回来继续）

---

#import 

typedef NS_ENUM(NSInteger, wherefrom){ 
    from1 = 1,           
    from2 = 2,            
    from3 = 3,            
};

@interface cutDownManager : NSObject
{
    dispatch_source_t _timer;
}
@property (nonatomic,assign)__block int timeLeft;
@property (nonatomic,assign) wherefrom from;  //用于区别哪个倒计时
+ (id)sharedTimerManager;
- (void)countDown;

@end

#import "cutDownManager.h"

@implementation cutDownManager

+ (id)sharedTimerManager{
    static cutDownManager *manager =nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        if (manager ==nil) {
            manager = [[self alloc] init];
        }
    });
    return manager;
}

- (void)countDown{

    if (_timeLeft >0) {
        if (_timer) {
            dispatch_source_cancel(_timer);
        }
        dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0);
        _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER,0, 0,queue);
        dispatch_source_set_timer(_timer,dispatch_walltime(NULL,0),1.0*NSEC_PER_SEC,0); //每秒执行
        dispatch_source_set_event_handler(_timer, ^{
            if(_timeLeft<=0){//倒计时结束，关闭
                dispatch_source_cancel(_timer);
            }else{
                _timeLeft--;
                DLog(@"----lefttime ======%d",_timeLeft);
            }
        });
        dispatch_resume(_timer);
    }
}


@end

应用

//获取短信验证码
- (IBAction)getMsgCode{ 
  timeout = 60; //倒计时时间
  [self startTime];
}


-(void)startTime
{

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue);
    dispatch_source_set_timer(_timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行

    dispatch_source_set_event_handler(_timer, ^{
        if(timeout<=0){ //倒计时结束，关闭
            dispatch_source_cancel(_timer);
            dispatch_async(dispatch_get_main_queue(), ^{
                //设置界面的按钮显示 根据自己需求设置
                _getMsglabel.text = @"重新获取";
                _getMsgBtn.userInteractionEnabled = YES;
            });
        }else{
            int seconds = timeout % 120;
            NSString *strTime = [NSString stringWithFormat:@"%.2d", seconds];

            dispatch_async(dispatch_get_main_queue(), ^{
                //设置界面的按钮显示 根据自己需求设置
                _getMsglabel.text = [NSString stringWithFormat:@"%@s",strTime];
                _getMsgBtn.userInteractionEnabled = NO;
            });
            timeout--;
            DLog(@"---------%d",timeout);
        }
    });

    //启动
    dispatch_resume(_timer);
}

-(void)viewWillDisappear:(BOOL)animated
{

    [super viewWillDisappear:animated];

    //掐掉倒计时
//    if (_timer && timeout > 0) {
//        dispatch_source_cancel(_timer);
//    }

    if (timeout >0) {

        cutDownManager *manager = [cutDownManager sharedTimerManager];

            manager.timeLeft = timeout;
            manager.from = from1;

            [manager countDown];

        timeout = 0;//置为0，释放controller
    }
}


-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    cutDownManager *manager = [cutDownManager sharedTimerManager];

    int temp = manager.timeLeft;

    if (temp > 0 && (manager.from == from1)) {

        timeout = temp;//倒计时时间
        _getMsgBtn.enabled =NO;

        [self startTime];

    }else{
        _getMsgBtn.enabled =YES;
    }

}