参数 SwiftUI 中的可选绑定

Question

这是我的可选绑定

@Binding var showSheetModifFile : Bool?
@Binding var fileToModify : File?

init( showSheetModifFile : Binding<Bool?>? = nil, fileToModify : Binding<File?>? = nil) {
    _showSheetModifFile = showSheetModifFile ?? Binding.constant(nil)
    _fileToModify = fileToModify ?? Binding.constant(nil)
}    

所以现在当我尝试调用这个构造函数时：

@State var showModifFileSheet : Bool? = false
@State var fileToModify : File? = File()
...

SingleFileView(showSheetModifFile: self.$showModifFileSheet, fileToModify: self.$fileToModify)

我收到了这个错误：

'Binding' 不能转换为'Binding?'

Answer 1

为此目的有一个特殊的 Binding 构造函数

SingleFileView(showSheetModifFile: Binding(self.$showModifFileSheet), 
   fileToModify: Binding(self.$fileToModify))

更新：替代解决方案

struct FileDemoView: View {
    @State var showModifFileSheet : Bool? = false
    @State var fileToModify : File? = File()

    var body: some View {
        SingleFileView(showSheetModifFile: $showModifFileSheet, fileToModify: $fileToModify)
    }

}


struct SingleFileView: View {
    @Binding var showSheetModifFile : Bool?
    @Binding var fileToModify : File?


    init(showSheetModifFile : Binding<Bool?> = .constant(nil), fileToModify : Binding<File?> = .constant(nil)) {
        _showSheetModifFile = showSheetModifFile
        _fileToModify = fileToModify
    }

    var body: some View {
        Text("")
    }
}