iOS 分类之按钮倒计时UIButton+CountDown

最新推荐文章于 2020-03-24 17:48:06 发布

原创最新推荐文章于 2020-03-24 17:48:06 发布 · 892 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#ios #uibutton #定时器

iOS-类别专栏收录该内容

6 篇文章

订阅专栏

这篇博客介绍了如何在iOS中为UIButton添加倒计时功能，包括使用UIButton+CountDown类别进行扩展，并参考了关于NSTimer在后台运行及锁屏时的处理策略。

UIButton+CountDown.h


#import <UIKit/UIKit.h>

typedef void(^RunBlock)(UIButton *button, NSInteger totalTime, NSInteger leftTime);
typedef void(^EndBlock)(UIButton *button);

@interface UIButton (CountDown)

/**
 *  倒计时按钮
 *
 *  @param duration 总时间
 *  @param runBlock 倒计时期间回调
 *  @param endBlock 倒计时结束回调
 */
- (void)startWithDuration:(NSInteger)duration
                  running:(RunBlock)runBlock
                 finished:(EndBlock)endBlock;
@end

UIButton+CountDown.m


#import "UIButton+CountDown.h"

@implementation UIButton (CountDown)

- (void)startWithDuration:(NSInteger)duration running:(RunBlock)runBlock finished:(EndBlock)endBlock
{
    __block NSInteger timeOut = duration;
    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, ^{

        if (timeOut <= 0) {

            dispatch_source_cancel(_timer);
            dispatch_async(dispatch_get_main_queue(), ^{
                endBlock(self);
            });
        } else {

            int allTime = (int)duration + 1;
            int seconds = timeOut % allTime;
            dispatch_async(dispatch_get_main_queue(), ^{
                runBlock(self, duration, seconds);
            });
            timeOut--;
        }
    });
    dispatch_resume(_timer);
}

@end

Tips: 

倒计时除了GCD还可以使用NSTimer实现，但是有一个问题，也是我的测试反馈的：

应用进入后台一段时间，倒计时不工作，它只会从上一次消失的时间开始继续工作。

朋友们可以搜索“NSTimer 进入后台”，网上是说：进入后台，定时器线程被挂起，进入前台才继续工作。

所以，如果你有这方面的需求，而且是在不影响其他工作（比如音视频播放），可以在 AppDelegate.m 中添加如下代码：


- (void)applicationDidEnterBackground:(UIApplication *)application {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.

    __block UIBackgroundTaskIdentifier backgroundTask;

    backgroundTask = [application beginBackgroundTaskWithExpirationHandler:^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (backgroundTask != UIBackgroundTaskInvalid)
            {
                backgroundTask = UIBackgroundTaskInvalid;
            }
        });
    }];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (backgroundTask != UIBackgroundTaskInvalid)
            {
                backgroundTask = UIBackgroundTaskInvalid;
            }
        });
    });
}