14 回答

• 39

  在当前代码中，保存当前上下文的 GState ，将其配置为绘制阴影..并将其恢复为将其配置为绘制阴影之前的状态 . 然后，最后，您调用超类的 drawRect 实现： .

  任何应该受阴影设置影响的绘图都需要在之后发生

  CGContextSetShadow(currentContext, CGSizeMake(-15, 20), 5);
  

  但之前

  CGContextRestoreGState(currentContext);
  

  所以，如果你希望超类的 drawRect: 在阴影中是'wrapped'，那么如果重新安排你的代码怎么样呢？

  - (void)drawRect:(CGRect)rect {
      CGContextRef currentContext = UIGraphicsGetCurrentContext();
      CGContextSaveGState(currentContext);
      CGContextSetShadow(currentContext, CGSizeMake(-15, 20), 5);
      [super drawRect: rect];
      CGContextRestoreGState(currentContext);
  }
  

  回复于 2024-04-30T12:32:42+08:00
• 17

  一种更简单的方法是在初始化时设置视图的一些图层属性：

  self.layer.masksToBounds = NO;
  self.layer.shadowOffset = CGSizeMake(-15, 20);
  self.layer.shadowRadius = 5;
  self.layer.shadowOpacity = 0.5;
  

  您需要导入QuartzCore .

  #import <QuartzCore/QuartzCore.h>
  

  回复于 2024-04-30T12:32:42+08:00
• 13

  self.layer.masksToBounds = NO;
  self.layer.cornerRadius = 8; // if you like rounded corners
  self.layer.shadowOffset = CGSizeMake(-15, 20);
  self.layer.shadowRadius = 5;
  self.layer.shadowOpacity = 0.5;
  

  这会降低应用程序的速度 . 只要您的视图明显是矩形，添加以下行可以提高性能：

  self.layer.shadowPath = [UIBezierPath bezierPathWithRect:self.bounds].CGPath;
  

  回复于 2024-04-30T12:32:42+08:00
• 152

  相同的解决方案，但只是提醒您：您可以直接在故事板中定义阴影 .

  例如：

  

  回复于 2024-04-30T12:32:42+08:00
• 3

  你可以尝试这个......你可以玩这些值 . shadowRadius 决定了模糊量 . shadowOffset 指示阴影的去向 .

  Swift 2.0

  let radius: CGFloat = demoView.frame.width / 2.0 //change it to .height if you need spread for height
  let shadowPath = UIBezierPath(rect: CGRect(x: 0, y: 0, width: 2.1 * radius, height: demoView.frame.height))
  //Change 2.1 to amount of spread you need and for height replace the code for height
  
  demoView.layer.cornerRadius = 2
  demoView.layer.shadowColor = UIColor.blackColor().CGColor
  demoView.layer.shadowOffset = CGSize(width: 0.5, height: 0.4)  //Here you control x and y
  demoView.layer.shadowOpacity = 0.5
  demoView.layer.shadowRadius = 5.0 //Here your control your blur
  demoView.layer.masksToBounds =  false
  demoView.layer.shadowPath = shadowPath.CGPath
  

  Swift 3.0

  let radius: CGFloat = demoView.frame.width / 2.0 //change it to .height if you need spread for height 
  let shadowPath = UIBezierPath(rect: CGRect(x: 0, y: 0, width: 2.1 * radius, height: demoView.frame.height)) 
  //Change 2.1 to amount of spread you need and for height replace the code for height
  
  demoView.layer.cornerRadius = 2
  demoView.layer.shadowColor = UIColor.black.cgColor
  demoView.layer.shadowOffset = CGSize(width: 0.5, height: 0.4)  //Here you control x and y
  demoView.layer.shadowOpacity = 0.5
  demoView.layer.shadowRadius = 5.0 //Here your control your blur
  demoView.layer.masksToBounds =  false
  demoView.layer.shadowPath = shadowPath.cgPath
  

  传播的例子

  

  创建基本阴影

  demoView.layer.cornerRadius = 2
      demoView.layer.shadowColor = UIColor.blackColor().CGColor
      demoView.layer.shadowOffset = CGSizeMake(0.5, 4.0); //Here your control your spread
      demoView.layer.shadowOpacity = 0.5 
      demoView.layer.shadowRadius = 5.0 //Here your control your blur
  

  Swift 2.0中的基本阴影示例

  

  回复于 2024-04-30T12:32:42+08:00
• 93

  使用Interface Builder简单而干净的解决方案

  在项目中添加名为UIView.swift的文件（或者只将其粘贴到任何文件中）：

  import UIKit
  
  @IBDesignable extension UIView {
  
      /* The color of the shadow. Defaults to opaque black. Colors created
      * from patterns are currently NOT supported. Animatable. */
      @IBInspectable var shadowColor: UIColor? {
          set {
              layer.shadowColor = newValue!.CGColor
          }
          get {
              if let color = layer.shadowColor {
                  return UIColor(CGColor:color)
              }
              else {
                  return nil
              }
          }
      }
  
      /* The opacity of the shadow. Defaults to 0. Specifying a value outside the
      * [0,1] range will give undefined results. Animatable. */
      @IBInspectable var shadowOpacity: Float {
          set {
              layer.shadowOpacity = newValue
          }
          get {
              return layer.shadowOpacity
          }
      }
  
      /* The shadow offset. Defaults to (0, -3). Animatable. */
      @IBInspectable var shadowOffset: CGPoint {
          set {
              layer.shadowOffset = CGSize(width: newValue.x, height: newValue.y)
          }
          get {
              return CGPoint(x: layer.shadowOffset.width, y:layer.shadowOffset.height)
          }
      }
  
      /* The blur radius used to create the shadow. Defaults to 3. Animatable. */
      @IBInspectable var shadowRadius: CGFloat {
          set {
              layer.shadowRadius = newValue
          }
          get {
              return layer.shadowRadius
          }
      }
  }
  

  然后，这将在Interface Builder中为Utilities面板> Attributes Inspector中的每个视图提供：

  

  您现在可以轻松设置阴影 .

  笔记：

  • 阴影不会出现在IB中，仅在运行时出现 .
  • 正如Mazen Kasser所说

  对于未能使其工作的人[...]确保未启用剪辑子视图（clipsToBounds）

  回复于 2024-04-30T12:32:42+08:00
• 778

  我用它作为我的utils的一部分 . 有了这个，我们不仅可以设置阴影，还可以为任何 UIView 获得圆角 . 您也可以设置您喜欢的颜色阴影 . 通常黑色是首选，但有时，当背景为非白色时，您可能需要其他东西 . 这是我用的 -

  in utils.m
  + (void)roundedLayer:(CALayer *)viewLayer 
                radius:(float)r 
                shadow:(BOOL)s
  {
      [viewLayer setMasksToBounds:YES];
      [viewLayer setCornerRadius:r];        
      [viewLayer setBorderColor:[RGB(180, 180, 180) CGColor]];
      [viewLayer setBorderWidth:1.0f];
      if(s)
      {
          [viewLayer setShadowColor:[RGB(0, 0, 0) CGColor]];
          [viewLayer setShadowOffset:CGSizeMake(0, 0)];
          [viewLayer setShadowOpacity:1];
          [viewLayer setShadowRadius:2.0];
      }
      return;
  }
  

  要使用它，我们需要调用它 - [utils roundedLayer:yourview.layer radius:5.0f shadow:YES];

  回复于 2024-04-30T12:32:42+08:00
• 1

  斯威夫特3

  extension UIView {
      func installShadow() {
          layer.cornerRadius = 2
          layer.masksToBounds = false
          layer.shadowColor = UIColor.black.cgColor
          layer.shadowOffset = CGSize(width: 0, height: 1)
          layer.shadowOpacity = 0.45
          layer.shadowPath = UIBezierPath(rect: bounds).cgPath
          layer.shadowRadius = 1.0
      }
  }
  

  回复于 2024-04-30T12:32:42+08:00
• 227

  对于那些在尝试所有答案后未能使其工作的人（正如我自己！），只需确保在属性检查器中未启用 Clip Subviews ...

  回复于 2024-04-30T12:32:42+08:00
• 0

  如果您想使用StoryBoard并且不想继续输入运行时属性，您可以轻松地创建视图扩展并使其在故事板中可用 .

  第1步 . 创建扩展

  extension UIView {
  
  @IBInspectable var shadowRadius: CGFloat {
      get {
          return layer.shadowRadius
      }
      set {
          layer.shadowRadius = newValue
      }
  }
  
  @IBInspectable var shadowOpacity: Float {
      get {
          return layer.shadowOpacity
      }
      set {
          layer.shadowOpacity = newValue
      }
  }
  
  @IBInspectable var shadowOffset: CGSize {
      get {
          return layer.shadowOffset
      }
      set {
          layer.shadowOffset = newValue
      }
  }
  
  @IBInspectable var maskToBound: Bool {
      get {
          return layer.masksToBounds
      }
      set {
          layer.masksToBounds = newValue
      }
  }
  }
  

  第2步 . 您现在可以在故事板中使用这些属性
  

  回复于 2024-04-30T12:32:42+08:00
• 0

  您可以使用我为阴影和角半径创建的效用函数，如下所示：

  - (void)addShadowWithRadius:(CGFloat)shadowRadius withShadowOpacity:(CGFloat)shadowOpacity withShadowOffset:(CGSize)shadowOffset withShadowColor:(UIColor *)shadowColor withCornerRadius:(CGFloat)cornerRadius withBorderColor:(UIColor *)borderColor withBorderWidth:(CGFloat)borderWidth forView:(UIView *)view{
  
      // drop shadow
      [view.layer setShadowRadius:shadowRadius];
      [view.layer setShadowOpacity:shadowOpacity];
      [view.layer setShadowOffset:shadowOffset];
      [view.layer setShadowColor:shadowColor.CGColor];
  
      // border radius
      [view.layer setCornerRadius:cornerRadius];
  
      // border
      [view.layer setBorderColor:borderColor.CGColor];
      [view.layer setBorderWidth:borderWidth];
  }
  

  希望它能帮到你!!!

  回复于 2024-04-30T12:32:42+08:00
• 7

  所有答案都很好，但我想补充一点

  如果在有表格单元格时遇到问题，则Deque新单元格中的阴影不匹配，因此在这种情况下，您需要将影子代码放在layoutSubviews方法中，以便它在所有条件下都能很好地运行 .

  -(void)layoutSubviews{
      [super layoutSubviews];
  
      [self.contentView setNeedsLayout];
      [self.contentView layoutIfNeeded];
      [VPShadow applyShadowView:self];
  }
  

  或者在ViewControllers中为特定视图放置以下方法中的阴影代码，以便它能够正常工作

  -(void)viewDidLayoutSubviews{
      [super viewDidLayoutSubviews];
  
      [self.viewShadow layoutIfNeeded];
      [VPShadow applyShadowView:self.viewShadow];
  }
  

  我为新的开发者修改了我的阴影实现，以获得更广泛的形式ex：

  /*!
   @brief Add shadow to a view.
  
   @param layer CALayer of the view.
  
   */
  +(void)applyShadowOnView:(CALayer *)layer OffsetX:(CGFloat)x OffsetY:(CGFloat)y blur:(CGFloat)radius opacity:(CGFloat)alpha RoundingCorners:(CGFloat)cornerRadius{
      UIBezierPath *shadowPath = [UIBezierPath bezierPathWithRoundedRect:layer.bounds cornerRadius:cornerRadius];
      layer.masksToBounds = NO;
      layer.shadowColor = [UIColor blackColor].CGColor;
      layer.shadowOffset = CGSizeMake(x,y);// shadow x and y
      layer.shadowOpacity = alpha;
      layer.shadowRadius = radius;// blur effect
      layer.shadowPath = shadowPath.CGPath;
  }
  

  回复于 2024-04-30T12:32:42+08:00
• 2

  斯威夫特3

  self.paddingView.layer.masksToBounds = false
  self.paddingView.layer.shadowOffset = CGSize(width: -15, height: 10)
  self.paddingView.layer.shadowRadius = 5
  self.paddingView.layer.shadowOpacity = 0.5
  

  回复于 2024-04-30T12:32:42+08:00
• 1

  对于Xamarians同事，答案的Xamarin.iOS / C＃版本如下所示：

  public override void DrawRect(CGRect area, UIViewPrintFormatter formatter)
  {
      CGContext currentContext = UIGraphics.GetCurrentContext();
      currentContext.SaveState();
      currentContext.SetShadow(new CGSize(-15, 20), 5);
      base.DrawRect(area, formatter);
      currentContext.RestoreState();                
  }
  

  主要区别在于您获取了 CGContext 的实例，您可以在其上直接调用相应的方法 .

  回复于 2024-04-30T12:32:42+08:00