简单的对倒计时进行封装

.h文件

+ (void)beginCodeWithBtn:(UIButton *)btn timeVlaueSum:(int)timeValue beginState:(void (^)())begin endState:(void (^)(int seconds))end;

.m文件

static dispatch_source_t _timer;

@implementation FYTimerCodeTool
//开始倒计时
+ (void)beginCodeWithBtn:(UIButton *)btn timeVlaueSum:(int)timeValue beginState:(void (^)())begin endState:(void (^)(int seconds))end{
    __block NSInteger time = timeValue; //倒计时时间
    
    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(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
 
                begin();
            });
            
        }else{
            
            int seconds = time % 60;
            dispatch_async(dispatch_get_main_queue(), ^{
                
                //设置按钮显示读秒效果
 
                
                end(seconds);
            });
            time--;
        }
    });
    dispatch_resume(_timer);
    
}
+ (void)cancelTimer{
    dispatch_source_cancel(_timer);

}