倒计时

先说一句废话吧，这份代码是我找的别人的O(∩_∩)O

创建UIButton的一个类目

#import <UIKit/UIKit.h>

@interface UIButton (CountDown)


/*
 *    倒计时按钮
 *    @param timeLine  倒计时总时间
 *    @param title     还没倒计时的title
 *    @param subTitle  倒计时的子名字 如：秒重新获取
 *    @param mColor    还没倒计时的背景颜色
 *    @param color     倒计时的背景颜色
 */

- (void)startWithTime:(NSInteger)timeLine title:(NSString *)title countDownTitle:(NSString *)subTitle mainColor:(UIColor *)mColor countColor:(UIColor *)color;

@end

#import "UIButton+CountDown.h"

@implementation UIButton (CountDown)


- (void)startWithTime:(NSInteger)timeLine title:(NSString *)title countDownTitle:(NSString *)subTitle mainColor:(UIColor *)mColor countColor:(UIColor *)color{

    // 倒计时时间
    __block NSInteger timeOut = timeLine;
    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);
    
    // 每秒执行一次
    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，关闭
        if (timeOut <= 0) {
            dispatch_source_cancel(_timer);
            
            dispatch_async(dispatch_get_main_queue(), ^{
                
                self.backgroundColor = mColor;
                [self setTitle:title forState:UIControlStateNormal];
                self.userInteractionEnabled = YES;
            });
            
        }else{
            //这个地方我稍微做了一下改动
            int minute  = (int)timeOut / 60;
            int seconds = timeOut % 60 + minute * 60;

            NSString * timeStr = [NSString stringWithFormat:@"%0.2d",seconds];
            
            dispatch_async(dispatch_get_main_queue(), ^{
                self.backgroundColor = color;
                [self setTitle:[NSString stringWithFormat:@"%@%@",timeStr,subTitle] forState:UIControlStateNormal];
                self.userInteractionEnabled = NO;
            });
            
            timeOut--;
        }
    });
    
    dispatch_resume(_timer);
}

@end

注意

如果是xib创建的UIButton,那么要在xib中设置一下type 为Custom，不然倒计时的时候，数字会闪动