iOS 动画效果。简单的提示消失
UILabel * label1 = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 320, 30)]; label1.text = @"qingjoin"; [self.view addSubview:label1]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; [UIView setAnimationDuration:3.0]; [UIView setAnimationDelegate:self]; label1.alpha =0.0; [UIView commitAnimations]; //3秒后消失