swift - 通过 UnsafeMutableRawPointer 导出 SwiftUI View

Question

我想返回一个 SwiftUI Text查看为 UnsafeMutableRawPointer , 遵守 C 调用约定，因此其他语言可以 FFI 进入它使用。

@_cdecl("hi")
func hi (txt: UnsafeMutablePointer<CChar>) -> () {
   var view = ViewBuilder.buildBlock(Text(String(cString: txt)))
   return UnsafeMutableRawPointer(Unmanaged.passUnretained(view).toOpaque())
}

但是我收到以下错误:

Cannot invoke 'passUnretained' with an argument list of type '(Text)'

如何获取 SwiftUI 的底层指针 Text对象？

Answer 1

用自己的类包装

@_cdecl("hi")
func hi (txt: UnsafeMutablePointer<CChar>) -> UnsafeMutableRawPointer {
   let view = ViewBuilder.buildBlock(Text(String(cString: txt)))
    return UnsafeMutableRawPointer(Unmanaged.passUnretained(Wrapper(text: view)).toOpaque())
}

final class Wrapper {
    let text: Text
    init(text: Text) {
        self.text = text
    }
}