Ios 如何使UIVisualEffectView淡入动画？

我有一个视图，我想覆盖一个模糊，并有它的动画。我在故事板中添加了名为blurField的UIVisualEffectView。这就是我破解的东西，有没有更干净的方法？谢谢

-(void)viewDidLoad {
    [super viewDidLoad];
    self.blurField.alpha = 0.0;
    [self performSelector:@selector(fillInBlur) withObject:nil afterDelay:3.0];
}

-(void)fillInBlur {
    self.blurField.alpha = 0.1;
    [self performSelector:@selector(fillInBlur1) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur1 {
    self.blurField.alpha = 0.2;
    [self performSelector:@selector(fillInBlur2) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur2 {
    self.blurField.alpha = 0.3;
    [self performSelector:@selector(fillInBlur3) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur3 {
    self.blurField.alpha = 0.4;
    [self performSelector:@selector(fillInBlur4) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur4 {
    self.blurField.alpha = 0.5;
    [self performSelector:@selector(fillInBlur5) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur5 {
    self.blurField.alpha = 0.6;
    [self performSelector:@selector(fillInBlur6) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur6 {
    self.blurField.alpha = 0.7;
    [self performSelector:@selector(fillInBlur7) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur7 {
    self.blurField.alpha = 0.8;
    [self performSelector:@selector(fillInBlur8) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur8 {
    self.blurField.alpha = 0.9;
    [self performSelector:@selector(fillInBlur9) withObject:nil afterDelay:0.03];
}

-(void)fillInBlur9 {
    self.blurField.alpha = 1.0;
}

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在iOS 8中，视觉效果视图不透明度的动画是非法且不可能的。这是因为它的特殊实现方式

在iOS 9中，您可以直接为模糊本身设置动画。从其

效果

为

nil

的UIVisualEffectView开始，然后在

动画：

块中将其

效果

设置为UIBlurEffect。模糊将使自身具有动画效果

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仍然存在一些限制，但是如果您遇到这些限制，运行时将为您的应用程序调用它们。关于这个主题，有一个很好的WWDC 2015视频。

谢谢@matt的帮助！