设置uiview.frame 不能正确的更新UI？

代码如下：

-(void)openMenu{
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.3];
self.leftMenu.frame = CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y, self.leftMenuWidth, self.view.frame.size.height);
self.mainView.frame = CGRectMake(self.view.frame.origin.x + self.leftMenuWidth, self.view.frame.origin.y, self.view.frame.size.width, self.view.frame.size.height);
self.blurEffectView.alpha = 0;
[self.mainView addSubview:self.blurEffectView];
self.blurEffectView.alpha = 1;
[UIView commitAnimations];
[self.blurEffectView addGestureRecognizer:self.tapGesture];
[self.view addGestureRecognizer:self.swipLeftGesture];
}

我在这段代码中更改了 mainView.frame的值然后做了一个动画，debug发现mainView = (x=100,y=0,width=320,height=558),值已经被改变了，但是实际上模拟里中的UI并没有更新mainView = (x=0,y=0,width=320,height=558)。

只有第一次跑到这段代码会有bug，之后都会成功。

编辑1：

注释掉 [self.mainView addSubview:self.blurEffectView]; 可以解决问题，但是还是需要blurEffectView

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改成这样试下：

-(void)openMenu{
self.blurEffectView.alpha = 0;
if (![self. self.mainView.subviews containsObject:self.bluerEffectView]) {
       [self.mainView addSubView:self.bluerEffectView];
}
[self.mainView addSubview:self.blurEffectView];
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.3];
self.leftMenu.frame = CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y, self.leftMenuWidth, self.view.frame.size.height);
self.mainView.frame = CGRectMake(self.view.frame.origin.x + self.leftMenuWidth, self.view.frame.origin.y, self.view.frame.size.width, self.view.frame.size.height);
self.blurEffectView.alpha = 1;
[UIView commitAnimations];
[self.blurEffectView addGestureRecognizer:self.tapGesture];
[self.view addGestureRecognizer:self.swipLeftGesture];
}