我正在尝试在收到按钮点击时执行这个基本的UIView动画:-(IBAction)buttonPress:(id)sender{self.sampleView.alpha=0.0;[UIViewanimateWithDuration:2.0delay:0.0options:UIViewAnimationOptionCurveEaseInOut|UIViewAnimationOptionBeginFromCurrentStateanimations:^{self.sampleView.alpha=1.0;}completion:NULL];}在单击按钮之前，View是可见的并且具有1.0的