import <UIKit/UIKit.h>

@interface UIButton (YasinTimerCategory)

• (void)startCountDownTime:(int)time withCountDownBlock:(void(^)(void))countDownBlock;

@end

import "UIButton+YasinTimerCategory.h"

static NSString *yasinTempText;

@implementation UIButton (YasinTimerCategory)

• (void)startCountDownTime:(int)time withCountDownBlock:(void(^)(void))countDownBlock{

  [self initButtonData];

  [self startTime:time];

  if (countDownBlock) {
  countDownBlock();
  }
  }

• (void)initButtonData{

  yasinTempText = [NSString stringWithFormat:@"%@",self.titleLabel.text];

}

• (void)startTime:(int)time{

  __block int timeout = time;

  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(), ^{
            
            [self setTitle:yasinTempText forState:UIControlStateNormal];
            self.userInteractionEnabled = YES;
            
        });
        
    }else{
        
        dispatch_async(dispatch_get_main_queue(), ^{
            
            NSString *text = [NSString stringWithFormat:@"%02d秒重新获取",timeout];
            [self setTitle:text forState:UIControlStateNormal];
            self.userInteractionEnabled = NO;
            
        });
        
        timeout --;
        
    }
  

  });

  dispatch_resume(_timer);

}

@end

调用方法
[self.verificationBtn startCountDownTime:60 withCountDownBlock:^{

        NSLog(@"开始倒计时");
        
        
        
    }];