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。

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];   
}    

你需要使用两个uiview来实现这一点。一个UIView会像阴影一样工作，另一个会为圆角边界工作。

下面是一个在协议帮助下的类方法的代码片段:

@implementation UIMethods

+ (UIView *)genComposeButton:(UIViewController <UIComposeButtonDelegate> *)observer;
{
    UIView *shadow = [[UIView alloc]init];
    shadow.layer.cornerRadius = 5.0;
    shadow.layer.shadowColor = [[UIColor blackColor] CGColor];
    shadow.layer.shadowOpacity = 1.0;
    shadow.layer.shadowRadius = 10.0;
    shadow.layer.shadowOffset = CGSizeMake(0.0f, -0.5f);

    UIButton *btnCompose = [[UIButton alloc]initWithFrame:CGRectMake(0, 0,60, 60)];
    [btnCompose setUserInteractionEnabled:YES];
    btnCompose.layer.cornerRadius = 30;
    btnCompose.layer.masksToBounds = YES;
    [btnCompose setImage:[UIImage imageNamed:@"60x60"] forState:UIControlStateNormal];
    [btnCompose addTarget:observer action:@selector(btnCompose_click:) forControlEvents:UIControlEventTouchUpInside];
    [shadow addSubview:btnCompose];
    return shadow;
}

在上面的代码中，btnCompose_click:将成为一个@required委托方法，该方法将在单击按钮时触发。

在这里我添加了一个按钮到我的UIViewController，像这样:

UIView *btnCompose = [UIMethods genComposeButton:self];
btnCompose.frame = CGRectMake(self.view.frame.size.width - 75,
                          self.view.frame.size.height - 75,
                          60, 60);
[self.view addSubview:btnCompose];

结果如下所示:

你需要使用shadowView和roundView

shadowView

必须有背景色 应该躺在roundView后面吗 窍门是将shadowView布局在里面，它的阴影需要发光。调整嵌入，使shadowView在roundView后面完全不可见

圆视图

必须剪辑子视图

的代码

addSubviews(shadowView, roundView)
roundView.addSubviews(titleLabel, subtitleLabel, imageView)

// need inset
shadowView.pinEdges(view: self, inset: UIEdgeInsets(constraintInsets: 2))
roundView.pinEdges(view: self)

do {
  shadowView.backgroundColor = .white // need background
  let layer = shadowView.layer
  layer.shadowColor = UIColor.black.cgColor
  layer.shadowRadius = 3
  layer.shadowOffset = CGSize(width: 3, height: 3)
  layer.shadowOpacity = 0.7
  layer.shouldRasterize = true
}

do {
  roundView.backgroundColor = .white
  let layer = roundView.layer
  layer.masksToBounds = true
  layer.cornerRadius = 5
}

或者你可以在不指定clipToBounds/maskToBounds的情况下这样做

layer.shadowColor = UIColor.gray.cgColor
layer.shadowOffset = CGSize(width: 3, height: 3)
layer.shadowOpacity = 0.8

Swift 4解决方案，使UICollectionViewCell圆形和添加阴影，没有任何扩展和并发症:)

注意:对于简单的视图，例如按钮。请看这篇文章中的@suragch的回答。 https://stackoverflow.com/a/34984063/7698092。按钮测试成功

以防有人还在努力使角落圆润，同时添加阴影。虽然这个解决方案适用于UICollectionViewCell，但它可以推广到任何视图。

这个技巧对我来说很有效，不需要做任何扩展和所有复杂的事情。我正在使用storyBoard。

技术

你必须在storyBoard的UICollectionViewCell中添加一个UIView(让我们说它是“containerView”)，并在这个containerView中添加所有必需的视图(按钮，图像等)。 见截图。

连接containerView的出口。在CellforItemAtIndexPath委托函数中添加以下代码行。

//adds shadow to the layer of cell

cell.layer.cornerRadius = 3.0
    cell.layer.masksToBounds = false
    cell.layer.shadowColor = UIColor.black.cgColor
    cell.layer.shadowOffset = CGSize(width: 0, height: 0)
    cell.layer.shadowOpacity = 0.6

//makes the cell round 

let containerView = cell.containerView!
    containerView.layer.cornerRadius = 8
    containerView.clipsToBounds = true

输出

查看模拟器截图

使用Swift 4和Xcode 9，这是一个用投影和边框舍入ImageView的工作示例。

    //set dimensions and position of image (in this case, centered)
    let imageHeight: CGFloat = 150, imageWidth: CGFloat = 150
    let xPosition = (self.view.frame.width / 2) - (imageWidth / 2)
    let yPosition = (self.view.frame.height / 2) - (imageHeight / 2)

    //set desired corner radius
    let cornerRadius: CGFloat = 20

    //create container for the image
    let imageContainer = UIView(frame: CGRect(x: xPosition, y: yPosition, width: imageWidth, height: imageHeight))

    //configure the container
    imageContainer.clipsToBounds = false
    imageContainer.layer.shadowColor = UIColor.black.cgColor
    imageContainer.layer.shadowOpacity = 1
    imageContainer.layer.shadowOffset = CGSize(width: 3.0, height: 3.0)
    imageContainer.layer.shadowRadius = 5
    imageContainer.layer.shadowPath = UIBezierPath(roundedRect: imageContainer.bounds, cornerRadius: cornerRadius).cgPath

    //create imageView
    let imageView = UIImageView(frame: imageContainer.bounds)

    //configure the imageView
    imageView.clipsToBounds = true
    imageView.layer.cornerRadius = cornerRadius
    //add a border (if required)
    imageView.layer.borderColor = UIColor.black.cgColor
    imageView.layer.borderWidth = 1.0
    //set the image
    imageView.image = UIImage(named: "bird")

    //add the views to the superview
    view.addSubview(imageContainer)
    imageContainer.addSubview(imageView)

如果你想让图像是圆形的:(并且显示为无边框)

let cornerRadius = imageWidth / 2