UIViewRepresentable自动大小-将UIKit UIView大小传递给SwiftUI

Question

假设您有一个UIKit视图，该视图想要确定其自身大小（通过internalContentSize或布局约束，该大小可能会更改）。例如：

/// Some UIKit view that wants to have a specific size
class YellowBoxUIKitView : UIView {

    init() {
        super.init(frame: .zero)
        self.backgroundColor = .yellow
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    override var intrinsicContentSize: CGSize {
        return CGSize(width: 100, height: 100)
    }

}

如何将其包装为SwiftUI UIViewRepresentable，并使其自动将UIView大小传递给SwiftUI？

struct YellowBoxView : UIViewRepresentable {

    func makeUIView(context: Context) -> YellowBoxUIKitView {
        // TODO: How do you pass the size from UIKit up to SwiftUI?
        YellowBoxUIKitView()
    }

    func updateUIView(_ uiView: YellowBoxUIKitView, context: Context) {
    }

}

SwiftUI不尊重UIView的大小，只是为其提供最大可能的宽度/高度。

可运行的示例：SizedUIViewRepresentableView

这里有一个类似的问题要求提供UITextView：Update UIViewRepresentable size from UIKit in SwiftUI

Answer 1

解决方案是为表示的UIView

显式设置压缩/拥抱优先级

通过Xcode 11.4 / iOS 13.4测试

struct YellowBoxView : UIViewRepresentable {

    func makeUIView(context: Context) -> YellowBoxUIKitView {
        let view = YellowBoxUIKitView()

        view.setContentHuggingPriority(.required, for: .horizontal) // << here !!
        view.setContentHuggingPriority(.required, for: .vertical)

        // the same for compression if needed

        return view
    }

    func updateUIView(_ uiView: YellowBoxUIKitView, context: Context) {
    }
}