SwiftUI簡化了許多TextField的.onChange修飾符

我正在尋找一種方法來簡化/重構在具有許多 TextField 的 SwiftUI 視圖中添加 .onChange(of:) 的方法。如果解決方案簡潔，我還會將修飾符移近適當的欄位，而不是在 ScrollView 的末尾。在這種情況下，所有 .onChange 修飾符都呼叫相同的函式。

例子：

.onChange(of: patientDetailVM.pubFirstName) { x in
    changeBackButton()
}
.onChange(of: patientDetailVM.pubLastName) { x in
    changeBackButton()
}
// ten  more times for other fields

我嘗試“oring”欄位。這不起作用：

.onChange(of:
            patientDetailVM.pubFirstName ||
            patientDetailVM.pubLastName
) { x in
    changeBackButton()
}

這是我要呼叫的簡單函式：

func changeBackButton() {
    withAnimation {
        showBackButton = false
        isEditing = true
    }
}

任何指導將不勝感激。Xcode 13.2.1 iOS 15

uj5u.com熱心網友回復：

任何時候復制代碼時，您都希望將其向下移動一級，以便可以重復使用相同的代碼。

這是一個解決方案，父視圖將保存一個變數，該變數將知道“名稱”作為一個整體是否發生了變化。

import SwiftUI
class PatientDetailViewModel: ObservableObject{
    @Published var pubFirstName: String = "John"
    @Published var pubLastName: String = "Smith"
}
struct TrackingChangesView: View {
    @StateObject var vm: PatientDetailViewModel = PatientDetailViewModel()
    ///Variable to know if there is a change
    @State var nameHasChanges: Bool = false
    var body: some View {
        NavigationView{
            NavigationLink("EditView", destination: {
                VStack{
                    TrackingChangesTextFieldView(hasChanges: $nameHasChanges, text: $vm.pubFirstName, titleKey: "first name")
                    TrackingChangesTextFieldView(hasChanges: $nameHasChanges, text: $vm.pubLastName, titleKey: "last name")
                    Button("save", action: {
                        //Once you verify saving the object reset the variable
                        nameHasChanges = false
                    })//Enable button when there are changes
                        .disabled(!nameHasChanges)
                }
                //Or track the single variable here
                .onChange(of: nameHasChanges, perform: {val in
                    //Your method here
                })
                //trigger back button with variable
                .navigationBarBackButtonHidden(nameHasChanges)
            })
            
        }
    }
}
struct TrackingChangesTextFieldView: View {
    //Lets the parent view know that there has been a change
    @Binding var hasChanges: Bool
    @Binding var text: String
    let titleKey: String
    var body: some View {
        TextField(titleKey, text: $text)
            .onChange(of: text, perform: { _ in
                //To keep it from reloading view if already true
                if !hasChanges{
                    hasChanges = true
                }
            })
    }
}
struct TrackingChangesView_Previews: PreviewProvider {
    static var previews: some View {
        TrackingChangesView()
    }
}

uj5u.com熱心網友回復：

你能做到這一點的另一種方式是讓兩個組合出版商pubFirstName和pubLastName。將以下功能添加到您的viewModel

var nameChanged: AnyPublisher<Bool, Never> {
        $patientDetailVM.pubFirstName
            .combineLatest($patientDetailVM.pubLastName)
            .map { firstName, lastName in
                if firstName != patientDetailVM.pubFirstName ||
                    lastName != patientDetailVM.pubLastName
                {
                    return true
                } else {
                    return false
                }
            }
            .eraseToAnyPublisher()
    }

并聽取nameChanged出版商onReceive的意見

.onReceive(of: patientDetailVM.nameChanged) { hasNameChanged in
    changeBackButton()
}

所以你可以聽名字或姓氏的變化。沒有測驗代碼，只是作為一個想法。

標籤：ios 代码 迅捷

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