有没有一种方法可以根据 SWIFT 中的屏幕尺寸自动调整图像或任何内容的大小？

Question

我一直在尝试寻找一种无需使用故事板即可根据屏幕大小以编程方式调整图像大小的方法？

Answer 1

转到 google（或您最喜欢的搜索引擎）并搜索 swift add constraints programmatically。这是非常非常基础的。

这是一个简单的例子：

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // create image view
        let imgView = UIImageView()
        
        imgView.backgroundColor = .systemYellow
        
        // create image
        let img = UIImage(systemName: "person.fill")
        imgView.image = img
        
        // add imageView to view
        view.addSubview(imgView)
        
        // use auto-layout
        imgView.translatesAutoresizingMaskIntoConstraints = false
        
        // respect safe area
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            // constrain imageView width to view safe-area width
            imgView.leadingAnchor.constraint(equalTo: g.leadingAnchor),
            imgView.trailingAnchor.constraint(equalTo: g.trailingAnchor),
            // aquare image view (1:1 ratio)
            imgView.heightAnchor.constraint(equalTo: imgView.widthAnchor),
            // center vertically
            imgView.centerYAnchor.constraint(equalTo: g.centerYAnchor),
        ])
        
    }
}

结果：

编辑 - 第二个例子...前三分之一，水平居中：

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        navigationController?.setNavigationBarHidden(true, animated: false)
        // create image view
        let imgView = UIImageView()
        
        imgView.backgroundColor = .systemYellow
        
        // create image
        let img = UIImage(systemName: "person.fill")
        imgView.image = img
        
        // add imageView to view
        view.addSubview(imgView)
        
        // use auto-layout
        imgView.translatesAutoresizingMaskIntoConstraints = false
        
        // respect safe area
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            
            // you want the image view at the top?
            imgView.topAnchor.constraint(equalTo: g.topAnchor),
            
            // one-third of the height of the view?
            imgView.heightAnchor.constraint(equalTo: g.heightAnchor, multiplier: 1.0 / 3.0),
            
            // you want a aquare image view (1:1 ratio)?
            imgView.widthAnchor.constraint(equalTo: imgView.heightAnchor),
            
            // you want it centered horizontally?
            imgView.centerXAnchor.constraint(equalTo: g.centerXAnchor),
            
        ])
        
    }
}

在 iPhone 8:

在 iPhone 12:

在 9.7" iPad Pro 上，横向：

有没有一种方法可以根据 SWIFT 中的屏幕尺寸自动调整图像或任何内容的大小？

is there a way to automatically resize an image or any content based on the screen size in SWIFT?

autolayout

swift