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将图像添加到UIVIew的子类

uiimage uikit uiview swift ios

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willd · 技术社区 · 2 年前

我有一个UIViewController,在其中我将UIIView设置为子视图,以在其中保存UIImage

class MyVIewController: UIViewController { 

  let myView = MyView()

     override func viewDidLoad() {
            super.viewDidLoad()
            myView.translatesAutoresizingMaskIntoConstraints =  false  
            myView.backgroundColor = .systemPink
           
            view.addSubview(myView)

    } 

  @objc func changeImageFunc(_ sender: Any) {

      //...extra code assigned .image (savedImage)
   myView.setImage(savedImage)

   }

class MyView: UIView {
    
     var imageView: UIImageView
    
    override init(frame: CGRect) {
     
        
        imageView = UIImageView()
        super.init(frame: frame)
        
        addSubview(imageView)

    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")

    }
    
    func setImage(_ image: UIImage) {
         // Set the image for the internal UIImageView
         imageView.image = image
     }
    
}

我试着把 imageView 直接在中的属性 chaneImageFunc 像这样

myView.imageView.image = savedImage

但也不起作用。如何显示保存在 myView 类到 MyViewController

0 回复 | 直到 2 年前

1

2

R4N 2 年前

看起来您从未为UIImageView(或MyView)建立过任何自动布局约束。因此,我的猜测是,即使显示UIView的背景色,imageView的框架也为0高0宽。当运行应用程序时,在Xcode中使用“调试视图层次结构”选项时,您应该能够看到这一点。

下面是一个调整代码以包括视图和imageView的自动布局约束的示例,这应该允许图像正确显示。

编辑:以编程方式设置视图时,它们将默认使用自动调整遮罩(弹簧和支柱),并将其转换为自动布局约束。若要设置程序化自动布局约束而不使其与自动保留掩码冲突(转换为自动布局约束),您需要通过设置禁用将授权掩码转换为自动布置约束 translatesAutoresizingMaskIntoConstraints 到 false 在目标视图上。

class MyViewController: UIViewController {
    
    let myView = MyView()
    

    override func viewDidLoad() {
        super.viewDidLoad()
        super.viewDidLoad()
        myView.translatesAutoresizingMaskIntoConstraints =  false
        myView.backgroundColor = .systemPink
        
        view.addSubview(myView)
        myView.widthAnchor.constraint(equalToConstant: 50).isActive = true
        myView.heightAnchor.constraint(equalToConstant: 50).isActive = true
        myView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        myView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
    }
    
    @IBAction @objc func changeImageFunc(_ sender: Any) {
        // just an example image
        let image = UIImage(systemName: "eraser")!
        myView.setImage(image)
    }
    
}

import UIKit

class MyView: UIView {

    var imageView: UIImageView
    
    override init(frame: CGRect) {
     
        
        imageView = UIImageView()
        imageView.translatesAutoresizingMaskIntoConstraints = false
        super.init(frame: frame)
        
        addSubview(imageView)
        imageView.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
        imageView.heightAnchor.constraint(equalTo: self.heightAnchor).isActive = true
        imageView.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
        imageView.centerYAnchor.constraint(equalTo: self.centerYAnchor).isActive = true

    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setImage(_ image: UIImage) {
         // Set the image for the internal UIImageView
         imageView.image = image
     }

}

结果是: