iOS开发-倒计时

倒计时

• 倒计时60s
• 倒计时HH-MM-SS

1.倒计时60s

- (void)countDownTime{
    __block NSInteger time = 59; //倒计时时间
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
    
    dispatch_source_set_timer(timer,DISPATCH_TIME_NOW,1.0*NSEC_PER_SEC, 0); //每秒执行
    
    dispatch_source_set_event_handler(timer, ^{
        
        if(time <= 0){ //倒计时结束，关闭
            
            dispatch_source_cancel(timer);
            
            dispatch_async(dispatch_get_main_queue(), ^{
                
                //设置按钮的样式
                self.timeCountButton.enabled = YES;
                [self.timeCountButton setTitle:@"重新发送" forState:UIControlStateNormal];
            
            });
            
        }else{
            
            int seconds = time % 60;
            dispatch_async(dispatch_get_main_queue(), ^{
                
                
                //设置label读秒效果
                self.timeCountButton.enabled = NO;
                [self.timeCountButton setTitle:[NSString stringWithFormat:@"%.2d秒后再次获取",seconds] forState:UIControlStateDisabled];
                
            });
            
            time--;
        }
    });
    
    dispatch_resume(timer);
}

很多时候在点击按钮发送短信的时候需要倒计时读秒

2.倒计时

- (void)activeCountDownActionWithtime:(NSString *)countTime{
    _timer = nil;
#if 0
    // 1.计算截止时间与当前时间差值
    // 倒计时的时间 测试数据
    NSString *deadlineStr = @"2019-08-19 12:00:00";
    // 当前时间的时间戳
    NSString *nowStr = [self getCurrentTimeyyyymmdd];
    // 计算时间差值
    NSInteger secondsCountDown = [self getDateDifferenceWithNowDateStr:nowStr deadlineStr:deadlineStr];
    
#endif
    NSInteger secondsCountDown = [countTime integerValue];
    if (secondsCountDown == 0) {
        self.timeLabel.text = @"0天00:00:00";
        _timer = nil;
        return;
    }
    // 2.使用GCD来实现倒计时 用GCD这个写有一个好处，跳页不会清零 跳页清零会出现倒计时错误的
    __weak __typeof(self) weakSelf = self;
    
    if (_timer == nil) {
        __block NSInteger timeout = secondsCountDown; // 倒计时时间
        
        if (timeout!=0) {
            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){ //  当倒计时结束时做需要的操作: 关闭 活动到期不能提交
                    dispatch_source_cancel(_timer);
                    _timer = nil;
                    dispatch_async(dispatch_get_main_queue(), ^{
                        weakSelf.timeLabel.text = @"0天00:00:00";
                    });
                } else { // 倒计时重新计算 时/分/秒
                    NSInteger days = (int)(timeout/(3600*24));
                    NSInteger hours = (int)((timeout-days*24*3600)/3600);
                    NSInteger minute = (int)(timeout-days*24*3600-hours*3600)/60;
                    NSInteger second = timeout - days*24*3600 - hours*3600 - minute*60;
                    NSString *strTime = [NSString stringWithFormat:@"0天%02ld:%02ld:%02ld", hours, minute, second];
                    dispatch_async(dispatch_get_main_queue(), ^{
                        if (days == 0) {
                            weakSelf.timeLabel.text = strTime;
                        } else {
                            weakSelf.timeLabel.text = [NSString stringWithFormat:@"%ld天%02ld:%02ld:%02ld", days, hours, minute, second];
                        }
                        
                    });
                    timeout--; // 递减 倒计时-1(总时间以秒来计算)
                }
            });
            dispatch_resume(_timer);
        }
    }
}

/**
 *  获取当天的字符串
 *
 *  @return 格式为年-月-日 时分秒
 */
- (NSString *)getCurrentTimeyyyymmdd {
    
    NSDate *now = [NSDate date];
    NSDateFormatter *formatDay = [[NSDateFormatter alloc] init];
    formatDay.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    NSString *dayStr = [formatDay stringFromDate:now];
    
    return dayStr;
}

/**
 *  获取时间差值  截止时间-当前时间
 *  nowDateStr : 当前时间
 *  deadlineStr : 截止时间
 *  @return 时间戳差值
 */
- (NSInteger)getDateDifferenceWithNowDateStr:(NSString*)nowDateStr deadlineStr:(NSString*)deadlineStr {
    
    NSInteger timeDifference = 0;
    
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yy-MM-dd HH:mm:ss"];
    NSDate *nowDate = [formatter dateFromString:nowDateStr];
    NSDate *deadline = [formatter dateFromString:deadlineStr];
    NSTimeInterval oldTime = [nowDate timeIntervalSince1970];
    NSTimeInterval newTime = [deadline timeIntervalSince1970];
    timeDifference = newTime - oldTime;
    
    return timeDifference;
}

在cell中倒计时需要每次加载倒计时先移除倒计时，防止返回或者跳转到下一个界面倒计时还在运行，导致内存崩溃。但是如果在当前页刷新按钮状态比如订单详情，刷新当前页状态改变了，倒计时需要移除，用一下方法。

[_timer invalidate];