- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    // 恢复倒计时
    [self.button az_cd_recover];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // ...   
  
    self.button.az_cd_identify = @"AZCountDownDemoBtn";
    self.button.az_cd_count = 60;
    self.button.az_cd_countdownBlock = ^(NSInteger countDown, UIButton * _Nonnull button) {
        [button setTitle:[NSString stringWithFormat:@"%lds",(long)countDown] forState:UIControlStateDisabled];
    };
    self.button.az_cd_endBlock = ^{
        NSLog(@"倒计时结束！");
    };
}

- (IBAction)startCountDown:(UIButton *)sender {
    // 用户点击开始倒计时
    [sender az_cd_start];
}