我不明白如何在 SwiftUI 中实现一个简单的选择器,显示一个值列表,这些值保留在不同 View 之间切换的所选值。顺便说一句,我可以使用选定的值通过 Combine 框架更新模型。
这是代码,但是 onAppear{}
/onDisappear{}
没有按预期工作:
struct CompanyView: View {
@ObservedObject var dataManager: DataManager = DataManager.shared
@State var selTipoAzienda = 0
var body: some View {
VStack {
companyPhoto
Text("Company view")
Form {
Picker(selection: $selTipoAzienda, label: Text("Tipo Azienda")) {
ForEach(0 ..< self.dataManager.company.tipoAziendaList.count) {
Text(self.dataManager.company.tipoAziendaList[$0])
}
}
}
Button(action: {self.dataManager.cambiaTipoAzienda(tipoAzienda: self.dataManager.company.tipoAziendaList[self.selTipoAzienda]) }) {
Image(systemName: "info.circle.fill")
.font(Font.system(size: 28))
.padding(.horizontal, 16)
}
}
// .onAppear{
// self.selTipoAzienda = self.dataManager.company.tipoAziendaList.firstIndex(of: self.dataManager.company.tipoAzienda) ?? 0
// }
// .onDisappear{
// self.dataManager.cambiaTipoAzienda(tipoAzienda: self.dataManager.company.tipoAziendaList[self.selTipoAzienda])
// }
}
我认为 binding 和 didSet 会是答案,但我不知道如何实现它们
最佳答案
提供的代码是不可编译/不可测试的,所以下面只是展示了一种方法(另见内联评论)
struct CompanyView: View {
@ObservedObject var dataManager: DataManager = DataManager.shared
@State var selTipoAzienda: Int
init() {
// set up initial value from persistent data manager
_selTipoAzienda = State(initialValue: self.dataManager.company.tipoAziendaList.firstIndex(of: self.dataManager.company.tipoAzienda) ?? 0)
}
var body: some View {
// inline proxy binding to intercept Picker changes
let boundSelTipoAzienda = Binding(get: { self.selTipoAzienda }, set: {
self.selTipoAzienda = $0
// store selected value into data manager
self.dataManager.cambiaTipoAzienda(tipoAzienda: self.dataManager.company.tipoAziendaList[$0])
})
return VStack {
companyPhoto
Text("Company view")
Form {
Picker(selection: boundSelTipoAzienda, label: Text("Tipo Azienda")) {
ForEach(0 ..< self.dataManager.company.tipoAziendaList.count) {
Text(self.dataManager.company.tipoAziendaList[$0])
}
}
}
Button(action: {self.dataManager.cambiaTipoAzienda(tipoAzienda: self.dataManager.company.tipoAziendaList[self.selTipoAzienda]) }) {
Image(systemName: "info.circle.fill")
.font(Font.system(size: 28))
.padding(.horizontal, 16)
}
}
}
}
关于swift - 选择器中的持久值在 SwiftUI 中更改 View ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61699032/