Swift iOS UIKit：Logo图片阴影效果不显示问题求助

你的代码里logoView.clipsToBounds = true是导致阴影无法显示的核心原因：阴影是绘制在视图layer的外部区域，而clipsToBounds = true会强制裁剪所有超出视图边界的内容，包括阴影，自然就看不到效果了。

下面给两种针对性的解决办法：

方案一：不需要图片裁剪到圆角时 #

直接移除clipsToBounds = true（或者设置为false）即可，修改后的代码：

func setUpLogo(){
    view.addSubview(logoView)
    logoView.translatesAutoresizingMaskIntoConstraints = false
    logoView.topAnchor.constraint(equalTo: view.topAnchor,constant: 220).isActive = true
    logoView.widthAnchor.constraint(equalToConstant: 140).isActive = true
    logoView.heightAnchor.constraint(equalToConstant: 190).isActive = true
    logoView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive  = true
    logoView.image = UIImage(named: "logoCharity")
    logoView.layer.cornerRadius = 11
    // 移除裁剪设置，阴影就能正常显示
    // logoView.clipsToBounds = true
    logoView.layer.shadowColor = UIColor.red.cgColor
    logoView.layer.shadowOpacity = 1
    logoView.layer.shadowOffset = CGSize(width: 0, height: 0)
    logoView.layer.shadowRadius = 10
}

方案二：需要同时保留图片圆角和阴影时 #

这种情况需要把UIImageView放到一个父视图里，将阴影添加到父视图上，让UIImageView只负责裁剪自身图片：

func setUpLogo(){
    // 创建专门承载阴影的父容器
    let shadowContainer = UIView()
    shadowContainer.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(shadowContainer)
    
    // 给父容器设置阴影
    shadowContainer.layer.shadowColor = UIColor.red.cgColor
    shadowContainer.layer.shadowOpacity = 1
    shadowContainer.layer.shadowOffset = CGSize(width: 0, height: 0)
    shadowContainer.layer.shadowRadius = 10
    
    // 将logoView添加到容器中
    shadowContainer.addSubview(logoView)
    logoView.translatesAutoresizingMaskIntoConstraints = false
    // 让logoView填满父容器
    logoView.topAnchor.constraint(equalTo: shadowContainer.topAnchor).isActive = true
    logoView.bottomAnchor.constraint(equalTo: shadowContainer.bottomAnchor).isActive = true
    logoView.leadingAnchor.constraint(equalTo: shadowContainer.leadingAnchor).isActive = true
    logoView.trailingAnchor.constraint(equalTo: shadowContainer.trailingAnchor).isActive = true
    
    logoView.image = UIImage(named: "logoCharity")
    logoView.layer.cornerRadius = 11
    logoView.clipsToBounds = true // 只裁剪自身图片，不影响父容器的阴影
    
    // 给父容器设置布局约束
    shadowContainer.topAnchor.constraint(equalTo: view.topAnchor,constant: 220).isActive = true
    shadowContainer.widthAnchor.constraint(equalToConstant: 140).isActive = true
    shadowContainer.heightAnchor.constraint(equalToConstant: 190).isActive = true
    shadowContainer.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive  = true
}

内容的提问来源于stack exchange，提问作者Jackie Tom