将容器的来源设置为另一个容器的麻烦 (Swift 4.2)

Question

我正在尝试将一个 UIView（红色）的原点和 width/height 设置为第二个 UIView（蓝色）。

我正在调用 UIView.frame.origin 或尺寸，但由于某种原因，y 原点不起作用。

我也尝试过布局约束（请参阅下面的注释），但这会覆盖我的蓝色完全约束视图。

然后我有一个按钮可以将红色视图动画化到一侧，这样您就可以看到下面的蓝色视图，但我无法让它们开始排列。下面是我的代码。在界面生成器中，我将两个 UIView 都设置为容器。蓝色完全受自动布局约束，红色没有约束。

import UIKit

class ViewController: UIViewController 
{

    @IBOutlet weak var blueContainer: UIView!
    @IBOutlet weak var redContainer: UIView!
    @IBOutlet weak var button: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        print(redContainer.frame)

        redContainer.frame.origin.x = view.frame.width/2
        redContainer.frame.size.width = view.frame.width

        //try to line up y with origin and size
        redContainer.frame.origin.y = blueContainer.frame.origin.y
        redContainer.frame.size.height = blueContainer.frame.size.height

        //also tried by using constraints
        //redContainer.topAnchor.constraint(equalTo: blueContainer.topAnchor).isActive = true
        //redContainer.heightAnchor.constraint(equalTo: blueContainer.heightAnchor).isActive = true

        print(redContainer.frame)
    }

    @IBAction func slideRed(_ sender: Any) {
        if redContainer.frame.origin.x == 0 {
            UIView.animate(withDuration: 0.5) {
                self.redContainer.frame.origin.x = self.view.frame.width/2
            }
            button.setTitle("Come Back Red!", for: .normal)
        } else {
            UIView.animate(withDuration: 0.5) {
                self.redContainer.frame.origin.x = 0
            }
            button.setTitle("Go Away Red!", for: .normal)
        }
    }
}

Answer 1

ViewDidLoad 不保证视图已经列出了它的约束。所以当blueContainer的frame和size是zero时，你不会看到对redContainer有任何影响。您应该使用 viewDidLayoutSubviews 从 blueContainer.

得到正确的 frame 和 size

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    redContainer.frame.origin.x = view.frame.width/2
    redContainer.frame.size.width = view.frame.width

    //try to line up y with origin and size
    redContainer.frame.origin.y = blueContainer.frame.origin.y
    redContainer.frame.size.height = blueContainer.frame.size.height
}

将容器的来源设置为另一个容器的麻烦 (Swift 4.2)

Setting origin of container to another container trouble (Swift 4.2)

user-interface

interface-builder

ios

swift