Swift中UIView同时设置可变高度与固定高度的约束调整方法

修改说明 #

你需要对原有代码做两处核心调整：

• 替换底部两个视图的高度约束：将原来的相对父视图高度占比约束heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.5)改为固定高度约束heightAnchor.constraint(equalToConstant: 200)，满足底部固定200高度的需求。
• 调整顶部两个视图的高度规则：删除原有相对父视图高度占比的约束，新增底部锚点绑定到底部视图的顶部锚点，顶部区域会自动填充父视图减去底部固定高度后的剩余空间，自动适配不同设备尺寸和横竖屏切换。

修改后完整可运行代码如下：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 先创建底部两个固定高度视图
        let frameBottomLeft = UIView()
        frameBottomLeft.backgroundColor = .systemGreen
        view.addSubview(frameBottomLeft)
        frameBottomLeft.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            frameBottomLeft.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            frameBottomLeft.heightAnchor.constraint(equalToConstant: 200),
            frameBottomLeft.leftAnchor.constraint(equalTo: view.leftAnchor),
            frameBottomLeft.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.5)
        ])

        let frameBottomRight = UIView()
        frameBottomRight.backgroundColor = .systemYellow
        view.addSubview(frameBottomRight)
        frameBottomRight.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            frameBottomRight.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            frameBottomRight.heightAnchor.constraint(equalToConstant: 200),
            frameBottomRight.rightAnchor.constraint(equalTo: view.rightAnchor),
            frameBottomRight.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.5)
        ])
        
        // 再创建顶部两个自适应高度视图
        let frameTopLeft = UIView()
        frameTopLeft.backgroundColor = .systemRed
        view.addSubview(frameTopLeft)
        frameTopLeft.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            frameTopLeft.topAnchor.constraint(equalTo: view.topAnchor),
            frameTopLeft.bottomAnchor.constraint(equalTo: frameBottomLeft.topAnchor),
            frameTopLeft.leftAnchor.constraint(equalTo: view.leftAnchor),
            frameTopLeft.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.5)
        ])

        let frameTopRight = UIView()
        frameTopRight.backgroundColor = .systemBlue
        view.addSubview(frameTopRight)
        frameTopRight.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            frameTopRight.topAnchor.constraint(equalTo: view.topAnchor),
            frameTopRight.bottomAnchor.constraint(equalTo: frameBottomRight.topAnchor),
            frameTopRight.rightAnchor.constraint(equalTo: view.rightAnchor),
            frameTopRight.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.5)
        ])
    }
}

内容的提问来源于stack exchange，提问作者user4806509