iOS实战——GCD实现时间倒数

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UILabel显示倒数

/** *  倒计时GCD通用方法 *  通常用的计时器都是用NSTimer，但是NSTimer在线程很吃紧的时候效果不佳，使用GCD计时相对更好 * *  @param seconds   倒计时间 单位：秒 *  @param showLable 需要显示的文本框 *  @param endBlock  倒计时结束后，回调的Block */+ (void)startTimerWithSeconds:(long)seconds showLable:(UILabel *)showLable endBlock:(void (^)())endBlock{    [self startTimerWithSeconds:seconds showLable:showLable strFormat:nil endBlock:endBlock];}

调下如下：

[BSTool startTimerWithSeconds:remainTime showLable:self.countdownLable endBlock:^{                self.countdownLable.text = @"订单超时";                [weakSelf.tableView reloadData];            }];

UILabel 格式显示倒数，并且倒数完成后需要进行另外的操作，则需要用block回调

/** *  倒计时GCD通用方法 *  通常用的计时器都是用NSTimer，但是NSTimer在线程很吃紧的时候效果不佳，使用GCD计时相对更好 * *  @param seconds   倒计时间 单位：秒 *  @param strFormat 格式化样式，如 "剩%@自动关闭" *  @param showLable 需要显示的文本框 *  @param endBlock  倒计时结束后，回调的Block */+ (void)startTimerWithSeconds:(long)seconds showLable:(UILabel *)showLable strFormat:(NSString *)format endBlock:(void (^)())endBlock{    __block long timeout = seconds; // 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_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，回调block            dispatch_source_cancel(_timer);            dispatch_async(dispatch_get_main_queue(), ^{                if (endBlock) {                    endBlock();                }            });        } else{            NSString *strTime = [NSString stringWithFormat:@"%02ld分%02ld秒",(long)(timeout % 3600 / 60), (long)(timeout  % 60)];            //回到主界面,显示倒计时            dispatch_async(dispatch_get_main_queue(), ^{                if (format) { // 判断是否要格式化                    showLable.text = [NSString stringWithFormat:format,strTime];                } else {                    showLable.text = strTime;                }            });            timeout--;        }    });    dispatch_resume(_timer);}

调用如下：

[BSTool startTimerWithSeconds:payResultModel.remainTime                            showLable:self.payStateDescLabel                            strFormat:@"剩%@自动关闭"                             endBlock:^{                                 self.payStateDescLabel.text = @"交易关闭";                             }];

获取短信验证码按钮倒数

// MARK:倒计时- (void)setTimer {    __block int timeout = 60;    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_walltime(NULL, 0), 1.0 * NSEC_PER_SEC, 0);    dispatch_source_set_event_handler(_timer, ^{        // 倒计时结束        if (timeout <= 0) {            dispatch_source_cancel(_timer);            dispatch_async(dispatch_get_main_queue(), ^{                sendCode.userInteractionEnabled = YES;                [sendCode setTitle:@"获取验证码" forState:UIControlStateNormal];                [sendCode setTitleColor:Color_A1A1A1 forState:UIControlStateNormal];            });        }        else {            int seconds = timeout % 61;            NSString *strTime = [NSString stringWithFormat:@"%.2d",seconds];            dispatch_async(dispatch_get_main_queue(), ^{                [sendCode setTitleColor:Color_A1A1A1 forState:UIControlStateNormal];                [sendCode setTitle:[NSString stringWithFormat:@"%@秒",strTime] forState:UIControlStateNormal];                sendCode.userInteractionEnabled = NO;            });            timeout--;        }    });    dispatch_resume(_timer);}

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