有没有一种捷径可以将一个视图的所有锚点分配给另一个视图的所有锚点

Question

假设我有一个容器视图，它有一个 imageView 和 blurEffectView 作为它的子视图。简而言之，我在容器视图内的这个图像上应用了 blurEffect。

我在没有 IB 的情况下使用锚点以编程方式配置自动布局。而imageView和blurredEffectView的anchors和它们的容器视图完全一样。

我想知道是否有一种简单/快速的方法来执行aView.allAnchors.equals(bView's allAnchors) 之类的操作？这样我们就可以省去很多重复的代码了。

- container
  - imageView
  - blurEffectView  

    let container: UIView = {
        let aView = UIView()
        aView.translatesAutoresizingMaskIntoConstraints = false
        return aView
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .white
        navigationController?.navigationBar.prefersLargeTitles = true
    }
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        configureLayout()
    }
    
    func configureLayout() {
        
        let imageView = UIImageView(image: UIImage(named: "Wang Fei"))
//        imageView.frame = container.bounds
        imageView.translatesAutoresizingMaskIntoConstraints = false
        imageView.contentMode = .scaleAspectFit
        container.addSubview(imageView)

        let blurEffect = UIBlurEffect(style: .dark)
        let blurredEffectView = UIVisualEffectView(effect: blurEffect)
        blurredEffectView.translatesAutoresizingMaskIntoConstraints = false
//        blurredEffectView.frame = imageView.bounds
        container.addSubview(blurredEffectView)
        
        view.addSubview(container)
        
        let g = view.safeAreaLayoutGuide
        NSLayoutConstraint.activate([
            container.topAnchor.constraint(equalTo: view.topAnchor),
            container.leadingAnchor.constraint(equalTo: g.leadingAnchor),
            container.trailingAnchor.constraint(equalTo: g.trailingAnchor),
            container.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.42),
            
            imageView.leadingAnchor.constraint(equalTo: container.leadingAnchor),
            imageView.trailingAnchor.constraint(equalTo: container.trailingAnchor),
            imageView.topAnchor.constraint(equalTo: container.topAnchor),
            imageView.bottomAnchor.constraint(equalTo: container.bottomAnchor),
            
            blurredEffectView.leadingAnchor.constraint(equalTo: container.leadingAnchor),
            blurredEffectView.trailingAnchor.constraint(equalTo: container.trailingAnchor),
            blurredEffectView.topAnchor.constraint(equalTo: container.topAnchor),
            blurredEffectView.bottomAnchor.constraint(equalTo: container.bottomAnchor)
        ])
    }

Answer 1

没有内置快捷方式。所以大多数人都会写一个。或者他们采用提供此类快捷方式的现有框架； SnapKit 是一个受欢迎的选择。

Answer 2

您可以像这样将重复代码包装在方便的extension 中 -

import UIKit

extension UIView {
    func setUpEdgeToEdge(in container: UIView, insets: UIEdgeInsets = .zero) {
        NSLayoutConstraint.activate([
            self.topAnchor.constraint(equalTo: container.topAnchor, constant: insets.top),
            self.leadingAnchor.constraint(equalTo: container.leadingAnchor, constant: insets.left),
            self.bottomAnchor.constraint(equalTo: container.bottomAnchor, constant: insets.bottom),
            self.trailingAnchor.constraint(equalTo: container.trailingAnchor, constant: -insets.right),
        ])
    }
}

现在你可以这样称呼它-

imageView.setUpEdgeToEdge(in: container)

// OR

imageView.setUpEdgeToEdge(in: container, insets: UIEdgeInsets(top: 10, left: 16, bottom: 10, right: 16))

Answer 3

您可以使用框架代替约束。此外，在viewDidLayoutSubviews 内的代码设置约束和视图中，这不是一个好方法。另外，请使用惰性。

这是可能的解决方案。

class TestViewController: UIViewController {
    private lazy var container: UIView = {
        let aView = UIView()
        aView.translatesAutoresizingMaskIntoConstraints = false
        return aView
    }()

    
    private lazy var imageView: UIImageView = {
        let imageView = UIImageView(image: UIImage(named: "Red"))
        imageView.translatesAutoresizingMaskIntoConstraints = true
        imageView.contentMode = .scaleAspectFit
        return imageView
    }()
    
    private lazy var blurredEffectView: UIVisualEffectView = {
        let blurEffect = UIBlurEffect(style: .dark)
        let blurredEffectView = UIVisualEffectView(effect: blurEffect)
        blurredEffectView.translatesAutoresizingMaskIntoConstraints = false
        return blurredEffectView
    }()
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .white
        navigationController?.navigationBar.prefersLargeTitles = true
        setViews()
    }

    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        self.imageView.frame = container.bounds
        self.blurredEffectView.frame = container.bounds
    }
    
    private func setViews() {
        view.addSubview(container)
        
        let g = view.safeAreaLayoutGuide
        NSLayoutConstraint.activate([
            container.topAnchor.constraint(equalTo: view.topAnchor),
            container.leadingAnchor.constraint(equalTo: g.leadingAnchor),
            container.trailingAnchor.constraint(equalTo: g.trailingAnchor),
            container.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.42)])
        
        container.addSubview(imageView)
        container.addSubview(blurredEffectView)
    }
}