import UIKit

extension UIView {

    func addShadow(shadowColor: UIColor, offSet: CGSize, opacity: Float, shadowRadius: CGFloat, cornerRadius: CGFloat, corners: UIRectCorner, fillColor: UIColor = .white) {

        let shadowLayer = CAShapeLayer()
        let size = CGSize(width: cornerRadius, height: cornerRadius)
        let cgPath = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: corners, cornerRadii: size).cgPath //1
        shadowLayer.path = cgPath //2
        shadowLayer.fillColor = fillColor.cgColor //3
        shadowLayer.shadowColor = shadowColor.cgColor //4
        shadowLayer.shadowPath = cgPath
        shadowLayer.shadowOffset = offSet //5
        shadowLayer.shadowOpacity = opacity
        shadowLayer.shadowRadius = shadowRadius
        self.layer.addSublayer(shadowLayer)
    }
}

旧线程仍然当前…

我编辑了Daniel Gindi的方法，使它可以用于按钮等。 如果有人需要圆角，或者想要将圆角和边框结合起来，它必须在视图层上设置，这个视图层被传递给这个方法。我还设置了栅格化来加快一点。

+ (UIView*)putView:(UIView*)view insideShadowWithColor:(CGColorRef)color 
                                 andRadius:(CGFloat)shadowRadius 
                                 andOffset:(CGSize)shadowOffset 
                                 andOpacity:(CGFloat)shadowOpacity
{
    // Must have same position like "view"
    UIView *shadow = [[UIView alloc] initWithFrame:view.frame]; 

    shadow.layer.contentsScale = [UIScreen mainScreen].scale;
    shadow.userInteractionEnabled = YES; // Modify this if needed
    shadow.layer.shadowColor = color;
    shadow.layer.shadowOffset = shadowOffset;
    shadow.layer.shadowRadius = shadowRadius;
    shadow.layer.masksToBounds = NO;
    shadow.clipsToBounds = NO;
    shadow.layer.shadowOpacity = shadowOpacity;
    shadow.layer.rasterizationScale = [UIScreen mainScreen].scale;
    shadow.layer.shouldRasterize = YES;

    [view.superview insertSubview:shadow belowSubview:view];
    [shadow addSubview:view];

    // Move view to the top left corner inside the shadowview 
    // ---> Buttons etc are working again :)
    view.frame = CGRectMake(0, 0, view.frame.size.width, view.frame.size.height);

    return shadow;
}

在swift 4中进行了测试

import UIKit

extension UIView {
    @IBInspectable var dropShadow: Bool {
        set{
            if newValue {
                layer.shadowColor = UIColor.black.cgColor
                layer.shadowOpacity = 0.4
                layer.shadowRadius = 1
                layer.shadowOffset = CGSize.zero
            } else {
                layer.shadowColor = UIColor.clear.cgColor
                layer.shadowOpacity = 0
                layer.shadowRadius = 0
                layer.shadowOffset = CGSize.zero
            }
        }
        get {
            return layer.shadowOpacity > 0
        }
    }
}

生产

如果你像这样在检查器中启用它:

它将添加用户定义的运行时属性，结果是:

(我之前添加了拐角半径= 8)

:)

我尝试了这篇文章中的很多解决方案，最终得到了下面的解决方案。这是完全证明解决方案，除非你需要在一个清晰的颜色视图下滴阴影。

- (void)addShadowWithRadius:(CGFloat)shadowRadius withOpacity:(CGFloat)shadowOpacity withOffset:(CGSize)shadowOffset withColor:(UIColor *)shadowColor withCornerradius:(CGFloat)cornerRadius
{
    UIView *viewShadow = [[UIView alloc]initWithFrame:self.frame];
    viewShadow.backgroundColor = [UIColor whiteColor];
    viewShadow.layer.shadowColor = shadowColor.CGColor;
    viewShadow.layer.shadowOffset = shadowOffset;
    viewShadow.layer.shadowRadius = shadowRadius;
    viewShadow.layer.shadowOpacity = shadowOpacity;
    viewShadow.layer.cornerRadius = cornerRadius;
    viewShadow.layer.masksToBounds = NO;
    [self.superview insertSubview:viewShadow belowSubview:self];

    [viewShadow setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0]];
    [self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0]];
    [self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:viewShadow attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0]];
    [self.superview addConstraint:[NSLayoutConstraint constraintWithItem:viewShadow attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:viewShadow attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0]];
    [self layoutIfNeeded];

    self.layer.cornerRadius = cornerRadius;
    self.layer.masksToBounds = YES;
}

Swift 3 & IBInspectable解决方案: 灵感来自Ade的解决方案

首先，创建一个UIView扩展:

//
//  UIView-Extension.swift
//  

import Foundation
import UIKit

@IBDesignable
extension UIView {
     // Shadow
     @IBInspectable var shadow: Bool {
          get {
               return layer.shadowOpacity > 0.0
          }
          set {
               if newValue == true {
                    self.addShadow()
               }
          }
     }

     fileprivate func addShadow(shadowColor: CGColor = UIColor.black.cgColor, shadowOffset: CGSize = CGSize(width: 3.0, height: 3.0), shadowOpacity: Float = 0.35, shadowRadius: CGFloat = 5.0) {
          let layer = self.layer
          layer.masksToBounds = false

          layer.shadowColor = shadowColor
          layer.shadowOffset = shadowOffset
          layer.shadowRadius = shadowRadius
          layer.shadowOpacity = shadowOpacity
          layer.shadowPath = UIBezierPath(roundedRect: layer.bounds, cornerRadius: layer.cornerRadius).cgPath

          let backgroundColor = self.backgroundColor?.cgColor
          self.backgroundColor = nil
          layer.backgroundColor =  backgroundColor
     }


     // Corner radius
     @IBInspectable var circle: Bool {
          get {
               return layer.cornerRadius == self.bounds.width*0.5
          }
          set {
               if newValue == true {
                    self.cornerRadius = self.bounds.width*0.5
               }
          }
     }

     @IBInspectable var cornerRadius: CGFloat {
          get {
               return self.layer.cornerRadius
          }

          set {
               self.layer.cornerRadius = newValue
          }
     }


     // Borders
     // Border width
     @IBInspectable
     public var borderWidth: CGFloat {
          set {
               layer.borderWidth = newValue
          }

          get {
               return layer.borderWidth
          }
     }

     // Border color
     @IBInspectable
     public var borderColor: UIColor? {
          set {
               layer.borderColor = newValue?.cgColor
          }

          get {
               if let borderColor = layer.borderColor {
                    return UIColor(cgColor: borderColor)
               }
               return nil
          }
     }
}

然后，在界面构建器中选择你的UIView，设置阴影ON和角半径，如下所示:

结果!

如果你不想像David c建议的那样改变你的nibs和视图层次结构，这个方法可以帮你。为你的UIImageView添加圆角和阴影只需使用这个方法，例如:

[Utils roundCornersForImageView:myImageView withCornerRadius:6.0 
andShadowOffset:2.0];

(!)出于性能原因，我不认为在像UITableView这样的东西中使用这段代码是个好主意，因为这段代码改变了视图层次结构。所以我会建议改变你的nib，并添加一个容器视图的阴影效果和使用戴维C.代码。

+ (void)roundCornersForImageView:(UIImageView *)imageView 
withCornerRadius:(float)cornerRadius andShadowOffset:(float)shadowOffset
{
    const float CORNER_RADIUS = cornerRadius;
    const float BORDER_WIDTH = 1.0; 
    const float SHADOW_OFFSET = shadowOffset;
    const float SHADOW_OPACITY = 0.8;
    const float SHADOW_RADIUS = 3.0;

    //Our old image now is just background image view with shadow
    UIImageView *backgroundImageView = imageView;
    UIView *superView = backgroundImageView.superview;

    //Make wider actual visible rect taking into account shadow
    //offset
    CGRect oldBackgroundFrame = backgroundImageView.frame;
    CGRect newBackgroundFrame = CGRectMake(oldBackgroundFrame.origin.x, oldBackgroundFrame.origin.y, oldBackgroundFrame.size.width + SHADOW_OFFSET, oldBackgroundFrame.size.height + SHADOW_OFFSET);
    [backgroundImageView removeFromSuperview];
    backgroundImageView.frame = newBackgroundFrame;        

    //Make new UIImageView with rounded corners and put our old image
    CGRect frameForRoundedImageView = CGRectMake(0, 0, oldBackgroundFrame.size.width, oldBackgroundFrame.size.height);
    UIImageView *roundedImageView = [[UIImageView alloc]initWithFrame:frameForRoundedImageView];
    roundedImageView.image = imageView.image;
    [roundedImageView.layer setCornerRadius:CORNER_RADIUS];
    [roundedImageView.layer setBorderColor:[UIColor lightGrayColor].CGColor];        
    [roundedImageView.layer setBorderWidth:BORDER_WIDTH]; 
    [roundedImageView.layer setMasksToBounds:YES];

    //Set shadow preferences
    [backgroundImageView setImage:nil];
    [backgroundImageView.layer setShadowColor:[UIColor blackColor].CGColor];
    [backgroundImageView.layer setShadowOpacity:SHADOW_OPACITY];
    [backgroundImageView.layer setShadowRadius:SHADOW_RADIUS];
    [backgroundImageView.layer setShadowOffset:CGSizeMake(SHADOW_OFFSET, SHADOW_OFFSET)];   

    //Add out two image views back to the view hierarchy.
    [backgroundImageView addSubview:roundedImageView];
    [superView addSubview:backgroundImageView];   
}