iOS获取短信验证码倒计时的两种实现方法

-(void)startTime{
  __block int timeout= 60; //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，关闭
      dispatch_source_cancel(_timer);
      dispatch_async(dispatch_get_main_queue(), ^{
        [self.getIdentifyCodeBt setTitle:@"获取验证码" forState:UIControlStateNormal];
        self.getIdentifyCodeBt.userInteractionEnabled = YES;
        [self.getIdentifyCodeBt setTitleColor:THEME_RED forState:UIControlStateNormal];
        self.getIdentifyCodeBt.backgroundColor = [UIColor whiteColor];
        self.getIdentifyCodeBt.layer.borderColor = THEME_RED.CGColor;
      });
    }else{
      dispatch_async(dispatch_get_main_queue(), ^{

        [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:1];
        [self.getIdentifyCodeBt setTitle:[NSString stringWithFormat:@"%zd秒后失效",timeout] forState:UIControlStateNormal];
        [self.getIdentifyCodeBt setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
        self.getIdentifyCodeBt.backgroundColor = [UIColor lightGrayColor];
        self.getIdentifyCodeBt.layer.borderColor = [UIColor clearColor].CGColor;
        self.getIdentifyCodeBt.clipsToBounds = YES;
        [UIView commitAnimations];
        self.getIdentifyCodeBt.userInteractionEnabled = NO;
      });
      timeout--;
    }
  });
  dispatch_resume(_timer);

}

#import <UIKit/UIKit.h>

@interface UIButton (XSCountDown)
- (void)xs_beginCountDownWithDuration:(NSTimeInterval)duration;
- (void)xs_stopCountDown;
@end

#import "UIButton+XSCountDown.h"

#import "ThemeColor.h"
static NSTimer *_countTimer;
static NSTimeInterval _count;
static NSString *_title;

@implementation UIButton (XSCountDown)

- (void)xs_beginCountDownWithDuration:(NSTimeInterval)duration {
  _title = self.titleLabel.text;
  _count = duration;
  _countTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(xs_updateTitle) userInfo:nil repeats:YES];
  [[NSRunLoop mainRunLoop] addTimer:_countTimer forMode:NSRunLoopCommonModes];
  self.userInteractionEnabled = NO;

   [self setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
  self.backgroundColor = [UIColor lightGrayColor];
  self.layer.borderColor = [UIColor clearColor].CGColor;
  self.clipsToBounds = YES;
}

- (void)xs_stopCountDown {
  [_countTimer invalidate];
  _countTimer = nil;
  _count = 60.0;
  [self setTitle:_title forState:UIControlStateNormal];
  self.userInteractionEnabled = YES;
}

- (void)xs_updateTitle {
  NSString *countString = [NSString stringWithFormat:@"%lis 后失效", (long)_count - 1];
  self.userInteractionEnabled = NO;
  [self setTitle:countString forState:UIControlStateNormal];
  if (_count-- <= 1.0) {
    [self xs_stopCountDown];
    [self setTitleColor:THEME_RED forState:UIControlStateNormal];
    self.backgroundColor = [UIColor whiteColor];
    self.layer.borderColor = THEME_RED.CGColor;
  }

}

@end

[self.verifyBt xs_beginCountDownWithDuration:60.0];