ios - 使用约束以编程方式排列按钮

Question

我有一个按钮数组，我正在遍历这些按钮并将它们添加到 View 中。每个按钮都应与前一个按钮相邻，因此我将前导约束设置为前一个按钮的尾随。但是按钮最终会层叠在一起，只显示最上面的按钮。

for k in 0 ..< buttons.count {

    view.addSubview(buttons[k])

    if k > 0 {
        buttons[k].leadingAnchor.constraint(equalTo: buttons[k-1].trailingAnchor).isActive = true
    }
}

---

编辑:

我不知道这是否是问题的一部分，但这是我创建按钮的方式。我将每个设置为 (0,0) 因为我不知道它们最终会在哪里。我假设约束会根据需要重新定位它们(​​第一次使用编程约束)。

let size = CGRect(x: 0, y: 0, width: buttonWidth, height: buttonHeight)
let button: UIButton = UIButton(frame: size)

Answer 1

这是一个使用 UIStackView 的简单 Playground 。您可以玩一下并适应您的目标。

UIStackView 如果您想避免手动创建约束，它们是非常灵活的组件。

//: A UIKit based Playground for presenting user interface

import UIKit
import PlaygroundSupport

class MyViewController: UIViewController {

    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white

        let buttons = createButtons()
        let stackView = createStackView(with: UILayoutConstraintAxis.vertical)

        buttons.forEach { button in
            stackView.addArrangedSubview(button)
        }

        view.addSubview(stackView)

        stackView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        stackView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
        self.view = view
    }

    func createStackView(with layout: UILayoutConstraintAxis) -> UIStackView {
        let stackView = UIStackView()
        stackView.translatesAutoresizingMaskIntoConstraints = false
        stackView.axis = layout
        stackView.distribution = .equalSpacing
        stackView.spacing = 0
        return stackView
    }

    func createButtons() -> [UIButton] {
        var buttons = [UIButton]()
        for x in 0..<5 {
            let button = UIButton(type: .custom)
            button.backgroundColor = .red
            button.translatesAutoresizingMaskIntoConstraints = false
            button.widthAnchor.constraint(equalToConstant: 50).isActive = true
            button.heightAnchor.constraint(equalToConstant: 100).isActive = true
            button.setTitle("Title \(x)", for: .normal)
            buttons.append(button)
        }
        return buttons
    }
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()