阴影+边界+角半径

    scrollview.backgroundColor = [UIColor whiteColor]; 
    CALayer *ScrlViewLayer = [scrollview layer];
    [ScrlViewLayer setMasksToBounds:NO ];
    [ScrlViewLayer setShadowColor:[[UIColor lightGrayColor] CGColor]];
    [ScrlViewLayer setShadowOpacity:1.0 ];
    [ScrlViewLayer setShadowRadius:6.0 ];
    [ScrlViewLayer setShadowOffset:CGSizeMake( 0 , 0 )];
    [ScrlViewLayer setShouldRasterize:YES];
    [ScrlViewLayer setCornerRadius:5.0];
    [ScrlViewLayer setBorderColor:[UIColor lightGrayColor].CGColor];
    [ScrlViewLayer setBorderWidth:1.0];
    [ScrlViewLayer setShadowPath:[UIBezierPath bezierPathWithRect:scrollview.bounds].CGPath];

在研究了一整天的圆角视图与阴影之后，我很高兴在这里发布我的自定义uiview类，希望结束这个问题:

RoundCornerShadowView.h

#import <UIKit/UIKit.h>

@interface RoundCornerShadowView : UIView

@end

RoundCornerShadowView.m

#import "RoundCornerShadowView.h"

@implementation RoundCornerShadowView

// *** must override this method, not the other method ***
// otherwise, the background corner doesn't disappear....
// @2015/05/29
-(void) layoutSubviews {
    [super layoutSubviews];//is must to ensure rightly layout children view

    //1. first, create Inner layer with content
    CALayer *innerView = [CALayer layer];
    innerView.frame = CGRectMake(0,0,self.bounds.size.width,self.bounds.size.height);
    //instead of: innerView.frame = self.frame;
    innerView.borderWidth = 1.0f;
    innerView.cornerRadius = 6.0f;
    innerView.masksToBounds = YES;
    innerView.borderColor = [[UIColor lightGrayColor] CGColor];
    innerView.backgroundColor = [[UIColor whiteColor] CGColor];
    //put the layer to the BOTTOM of layers is also a MUST step...
    //otherwise this layer will overlay the sub uiviews in current uiview...
    [self.layer insertSublayer:innerView atIndex:0];

    //2. then, create shadow with self layer
    self.layer.masksToBounds = NO;
    self.layer.shadowColor = [[UIColor darkGrayColor] CGColor];
    self.layer.shadowOpacity = 0.4f;
    //shadow length
    self.layer.shadowRadius = 2.0f;
    //no offset
    self.layer.shadowOffset = CGSizeMake(0, 0);
    //right down shadow
    //[self.layer setShadowOffset: CGSizeMake(1.0f, 1.0f)];

    //3. last but important, MUST clear current view background color, or the color will show in the corner!
    self.backgroundColor = [UIColor clearColor];
}

@end

所以，不需要在视图中添加子视图或在目标视图中添加子视图，只需在当前视图中添加一层，并执行3步即可完成!

仔细查看代码中的注释，这有助于理解组件!

这里有一个肯定有效的解决方案!

我已经创建了UIView扩展所需的边应用阴影如下

enum AIEdge:Int {
    case
    Top,
    Left,
    Bottom,
    Right,
    Top_Left,
    Top_Right,
    Bottom_Left,
    Bottom_Right,
    All,
    None
}

extension UIView {
        
    func applyShadowWithCornerRadius(color:UIColor, opacity:Float, radius: CGFloat, edge:AIEdge, shadowSpace:CGFloat, cornerRadius: CGFloat)    {

        var sizeOffset:CGSize = CGSize.zero
        
        switch edge {
        case .Top:
            sizeOffset = CGSize(width: 0, height: -shadowSpace)
        case .Left:
            sizeOffset = CGSize(width: -shadowSpace, height: 0)
        case .Bottom:
            sizeOffset = CGSize(width: 0, height: shadowSpace)
        case .Right:
            sizeOffset = CGSize(width: shadowSpace, height: 0)
            
            
        case .Top_Left:
            sizeOffset = CGSize(width: -shadowSpace, height: -shadowSpace)
        case .Top_Right:
            sizeOffset = CGSize(width: shadowSpace, height: -shadowSpace)
        case .Bottom_Left:
            sizeOffset = CGSize(width: -shadowSpace, height: shadowSpace)
        case .Bottom_Right:
            sizeOffset = CGSize(width: shadowSpace, height: shadowSpace)
            
            
        case .All:
            sizeOffset = CGSize(width: 0, height: 0)
        case .None:
            sizeOffset = CGSize.zero
        }

        self.layer.cornerRadius = cornerRadius
        self.layer.masksToBounds = true

        self.layer.shadowColor = color.cgColor
        self.layer.shadowOpacity = opacity
        self.layer.shadowOffset = sizeOffset
        self.layer.shadowRadius = radius
        self.layer.masksToBounds = false

        self.layer.shadowPath = UIBezierPath(roundedRect:self.bounds, cornerRadius:self.layer.cornerRadius).cgPath
    }
}

最后，你可以为你的UIView子类调用下面的阴影函数，你也可以指定边缘上应用阴影，尝试不同的变化根据你需要改变下面方法调用的参数。

viewRoundedToBeShadowedAsWell.applyShadowWithCornerRadius(color: .gray, opacity: 1, radius: 15, edge: AIEdge.All, shadowSpace: 15)

注意:如果仍然不工作，试着从主线程调用它

DispatchQueue.main.async {
   viewRoundedToBeShadowedAsWell.applyShadowWithCornerRadius(color: .gray, opacity: 1, radius: 15, edge: AIEdge.All, shadowSpace: 15)
}

希望有人觉得这有用!

以下是结果图片:

丹尼尔。Gindi上面的回答对我很有用!然而，我不得不做一些小的调整-改变shadowFrame的大小与视图的帧大小相同，并启用用户交互。以下是更新后的代码:

+ (UIView*)putView:(UIView*)view insideShadowWithColor:(UIColor*)color andRadius:(CGFloat)shadowRadius andOffset:(CGSize)shadowOffset andOpacity:(CGFloat)shadowOpacity
{
    CGRect shadowFrame; // Modify this if needed

    // Modified this line
    shadowFrame.size = CGSizeMake(view.frame.size.width, view.frame.size.height);

    shadowFrame.origin.x = 0.f;
    shadowFrame.origin.y = 0.f;
    UIView * shadow = [[UIView alloc] initWithFrame:shadowFrame];

    // Modified this line
    shadow.userInteractionEnabled = YES;
    shadow.layer.shadowColor = color.CGColor;
    shadow.layer.shadowOffset = shadowOffset;
    shadow.layer.shadowRadius = shadowRadius;
    shadow.layer.masksToBounds = NO;
    shadow.clipsToBounds = NO;
    shadow.layer.shadowOpacity = shadowOpacity;

    [shadow addSubview:view];
    return shadow;
}

我想补充的是，在我的情况下，我试图将此添加到第三方视图控制器，即我没有对代码的直接控制。下面是我如何使用上面的函数:

UIView *shadow = [self putView:vc.view 
         insideShadowWithColor:[UIColor blackColor]
                     andRadius:5.0 
                     andOffset:CGSizeMake(0.0, 0.0) 
                    andOpacity:1.0];
vc.view = shadow;
vc.view.layer.cornerRadius = 5.0;
vc.view.layer.masksToBounds = YES;

斯威夫特

// corner radius
blueView.layer.cornerRadius = 10

// border
blueView.layer.borderWidth = 1.0
blueView.layer.borderColor = UIColor.black.cgColor

// shadow
blueView.layer.shadowColor = UIColor.black.cgColor
blueView.layer.shadowOffset = CGSize(width: 3, height: 3)
blueView.layer.shadowOpacity = 0.7
blueView.layer.shadowRadius = 4.0

探索选择

问题1:阴影被剪掉了

如果我们希望将子层或子视图(如图像)的内容剪辑到视图的边界，该怎么办?

我们可以用

blueView.layer.masksToBounds = true

(另外,blueView。clipsToBounds = true给出相同的结果。)

但是，哦不!影子也被剪掉了，因为它在边界之外!怎么办呢?怎么办呢?

解决方案

阴影和边界使用单独的视图。基本视图是透明的，并且有阴影。边界视图将它拥有的任何其他子内容剪辑到它的边界。

// add the shadow to the base view
baseView.backgroundColor = UIColor.clear
baseView.layer.shadowColor = UIColor.black.cgColor
baseView.layer.shadowOffset = CGSize(width: 3, height: 3)
baseView.layer.shadowOpacity = 0.7
baseView.layer.shadowRadius = 4.0

// add the border to subview
let borderView = UIView()
borderView.frame = baseView.bounds
borderView.layer.cornerRadius = 10
borderView.layer.borderColor = UIColor.black.cgColor
borderView.layer.borderWidth = 1.0
borderView.layer.masksToBounds = true
baseView.addSubview(borderView)

// add any other subcontent that you want clipped
let otherSubContent = UIImageView()
otherSubContent.image = UIImage(named: "lion")
otherSubContent.frame = borderView.bounds
borderView.addSubview(otherSubContent)

结果如下:

问题2:表现不佳

添加圆角和阴影可以提高性能。您可以通过为阴影使用预定义的路径并指定它是栅格化来提高性能。下面的代码可以添加到上面的示例中。

baseView.layer.shadowPath = UIBezierPath(roundedRect: baseView.bounds, cornerRadius: 10).cgPath
baseView.layer.shouldRasterize = true
baseView.layer.rasterizationScale = UIScreen.main.scale

更多细节请看这篇文章。看这里和这里。

我们用Swift 4和Xcode 9测试了这个答案。

阴影+边界+角半径

    scrollview.backgroundColor = [UIColor whiteColor]; 
    CALayer *ScrlViewLayer = [scrollview layer];
    [ScrlViewLayer setMasksToBounds:NO ];
    [ScrlViewLayer setShadowColor:[[UIColor lightGrayColor] CGColor]];
    [ScrlViewLayer setShadowOpacity:1.0 ];
    [ScrlViewLayer setShadowRadius:6.0 ];
    [ScrlViewLayer setShadowOffset:CGSizeMake( 0 , 0 )];
    [ScrlViewLayer setShouldRasterize:YES];
    [ScrlViewLayer setCornerRadius:5.0];
    [ScrlViewLayer setBorderColor:[UIColor lightGrayColor].CGColor];
    [ScrlViewLayer setBorderWidth:1.0];
    [ScrlViewLayer setShadowPath:[UIBezierPath bezierPathWithRect:scrollview.bounds].CGPath];