获取验证码按钮以及点击后重复倒计时

UIButton样式

UIButton放在UITextField右边，这边就不放TF代码了，直接放UIButton样式代码，都是简单的写法。

            UIButton *verifyBtn = [UIButton buttonWithType:UIButtonTypeCustom];
            [verifyBtn setTitle:LocalString(@"获取验证码") forState:UIControlStateNormal];
            [verifyBtn.titleLabel setFont:[UIFont systemFontOfSize:13.f]];
            [verifyBtn setTitleColor:[UIColor bluecolor] forState:UIControlStateNormal];
            [verifyBtn addTarget:self action:@selector(getVerifyCode) forControlEvents:UIControlEventTouchUpInside];
            verifyBtn.layer.borderWidth = 0.5;
            verifyBtn.layer.borderColor = [UIColor colorWithHexString:@"4778CC"].CGColor;
            verifyBtn.layer.cornerRadius = 14.f;
            [self.view addSubview:verifyBtn];

再次获取验证码倒计时

倒计时需要用到计时功能，这里用的是GCD的计时器dispatch_source_set_timer，计时相对比较精确。

直接放代码

//开始倒计时
-(void)openCountdown{
    
    __block NSInteger time = 59; //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
                [self.verifyBtn setTitle:@"重新发送" forState:UIControlStateNormal];
                [_verifyBtn sizeToFit];
                //[self.verifyBtn setTitleColor:[UIColor darkTextColor] forState:UIControlStateNormal];
                //[_verifyBtn setButtonStyleWithColor:[UIColor blackColor] Width:1.f cornerRadius:5.f];
                self.verifyBtn.userInteractionEnabled = YES;
            });
            
        }else{
            
            int seconds = time % 60;
            dispatch_async(dispatch_get_main_queue(), ^{
                
                //设置按钮显示读秒效果
                [self.verifyBtn setTitle:[NSString stringWithFormat:@"%2ds", seconds] forState:UIControlStateNormal];
                [_verifyBtn sizeToFit];
                //[self.verifyBtn setTitleColor:[UIColor lightGrayColor] forState:UIControlStateNormal];
                //[_verifyBtn setButtonStyleWithColor:[UIColor lightGrayColor] Width:1.f cornerRadius:5.f];
                self.verifyBtn.userInteractionEnabled = NO;
            });
            time--;
        }
    });
    dispatch_resume(_timer);
}