ios 如何根据视角动态调整阴影？

Question

我用圆角 corners 将阴影添加到视图中，效果很好。但是当 frame 的视图改变时 shadow 不会根据视图改变它的大小。我尝试了以下方法：

-(void)addShadow:(UIView *)view withCornerRad : (int)radius{
    view.clipsToBounds = YES;
    CALayer *ViewLayer = view.layer;
    [ViewLayer setMasksToBounds:NO ];
    ViewLayer.shadowColor = [UIColor lightGrayColor].CGColor;
    ViewLayer.shadowOpacity = 1.0 ;
    ViewLayer.shadowRadius = 2.0 ;
    ViewLayer.shadowOffset = CGSizeMake( 0 , 0 );
    ViewLayer.cornerRadius = radius;
    ViewLayer.shadowPath = [UIBezierPath bezierPathWithRect:view.bounds].CGPath;
}

Answer 1

根据Apples view programming guide：

Views are responsible for drawing content, handling multitouch events, and managing the layout of any subviews.

所以你可以通过两种方式改变你的影子： 1. 通过重写 layoutSubviews 函数对 UIView 进行子类化，您可以在其中设置新的阴影大小。 2. 您可以重写控制器的 viewDidLayoutSubviews() 方法，您可以在其中设置新的阴影大小。

此致！

Answer 2

-(void)addShadow:(UIView *)view withCornerRad : (int)radius
{
    view.clipsToBounds = YES;
    CALayer *ViewLayer = view.layer;
    ViewLayer.shadowColor = [UIColor lightGrayColor].CGColor;
    ViewLayer.shadowRadius  = 10;
    ViewLayer.shadowOffset  = CGSizeMake(0.0f, 0.0f);
    ViewLayer.shadowOpacity = 2;
    ViewLayer.masksToBounds = NO;

    UIEdgeInsets shadowInsets     = UIEdgeInsetsMake(0, 0, 0, 0);
    UIBezierPath *shadowPath      = [UIBezierPath bezierPathWithRect:UIEdgeInsetsInsetRect(view.bounds, shadowInsets)];
    ViewLayer.shadowPath    = shadowPath.CGPath;


}

如果你想在视图的顶部、左侧、底部、右侧添加阴影，试试这个

ios 如何根据视角动态调整阴影？

How to adjust shadow dynamically with height of view in ios?

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