解決方案在最後面 !

__block int timeout = 59;//倒計時時間

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, ^{

            if(timeout<=0){ //倒計時結束，關閉

                dispatch_source_cancel(_timer);

dispatch_async(dispatch_get_main_queue(), ^{

                    [self.verificationBtnsetTitle:@"點選獲取驗證碼"forState:UIControlStateNormal];

                    //

self.verificationBtn.userInteractionEnabled =YES;

                });

            }else{

                int seconds = timeout % 60;

                NSString *strTime = [NSStringstringWithFormat:@"%.2d", seconds];

dispatch_async(dispatch_get_main_queue(), ^{

                    //

                    [UIViewbeginAnimations:nilcontext:nil];

                    [UIView setAnimationDuration:1];

                    [self.verificationBtnsetTitle:[NSStringstringWithFormat:@"重新獲取(%@)",strTime]forState:UIControlStateNormal];

                    [UIView commitAnimations];

self.verificationBtn.userInteractionEnabled =NO;

                });

                timeout--;

            }

        });

        dispatch_resume(_timer);

解決方案:將Button的Type修改為Custom;

程式碼: UIButton *button = [UIButtonbuttonWithType:UIButtonTypeCustom];

XIB