如何在 SwiftUI 中自动填充文本字段？

Question

我正在制作一个使用 SwiftUI 中的表单的应用程序，我想使用所述表单编辑本地存储的对象。

在这种情况下，我有一个蛋糕和一个饼干要存储在内存中，我有两个结构，一个用于蛋糕，一个用于饼干。

当用户选择 he/she 想要编辑的蛋糕或饼干时，表单字段应自动填充实际存储的可编辑蛋糕或饼干的属性。

结构是：

import Foundation

struct Cake {
    var name : String
    var style : String
    var decorations : String
}

struct Cookie{
    var name : String
    var style : String
}

我用于视图的代码是：

import SwiftUI

struct EditingForm: View {
    @State var cake : Cake = Cake(name: "Caprese", style: "Chocolate cake made with almonds flour", decorations: "Powdered Sugar")
    
    @State var cookie : Cookie = Cookie(name: "Chocolate Chip", style: "Cookie made with chocolate chips")
    
    @State var group : String = "Cake"
    @State var nameCake : String = ""
    @State var nameCookie : String = ""
    @State var styleCake : String = ""
    @State var cookiesChocolateChipsType : String = ""
    
    var body: some View {
        ZStack{
            Form{
                Section(header: Text("Sweet Details")
                ){
                    Menu("Select the sweet you want to edit") {
                        Button(action: {
                            group = "Cake"
                        }) {
                            Text("Cake")
                        }.foregroundColor(.black)
                        
                        Button(action: {
                            group = "Cookie"
                        }) {
                            Text("Cookie")
                        }
                    }
                }
                
                Section(header: Text("Decorations")
                ){
                    if(group == "Cake"){
                        TextField("Name of the cake", text: $nameCake)
                        TextField("Style of the cake", text: $styleCake)
                    } else if (group == "Cookie"){
                        TextField("Name of the cookie", text: $nameCookie)
                        TextField("Type of chocolate chips for the cookie", text: $cookiesChocolateChipsType)
                    }
                }
            }
        }
    }
    
}

Answer 1

您可以简单地使用 .onAppear() {} 修饰符。这意味着，当视图出现时，您的@State var 得到更新。

在您的示例中，代码如下所示：

import SwiftUI

struct EditingForm: View {
    @State var cake : Cake = Cake(name: "Caprese", style: "Chocolate cake made with almonds flour", decorations: "Powdered Sugar")
    
    @State var cookie : Cookie = Cookie(name: "Chocolate Chip", style: "Cookie made with chocolate chips")
    
    @State var group : String = "Cake"
    @State var nameCake : String = ""
    @State var nameCookie : String = ""
    @State var styleCake : String = ""
    @State var cookiesChocolateChipsType : String = ""
    
    var body: some View {
        ZStack{
            Form{
                Section(header: Text("Sweet Details")
                ){
                    Menu("Select the sweet you want to edit") {
                        Button(action: {
                            group = "Cake"
                        }) {
                            Text("Cake")
                        }.foregroundColor(.black)
                        
                        Button(action: {
                            group = "Cookie"
                        }) {
                            Text("Cookie")
                        }
                    }
                }
                
                Section(header: Text("Decorations")
                ){
                    if(group == "Cake"){
                        TextField("Name of the cake", text: $nameCake).onAppear() {
                          self.nameCake = self.cake.name
                        }
                        TextField("Style of the cake", text: $styleCake).onAppear() {
                          self.styleCake = self.cake.style
                        }
                    } else if (group == "Cookie"){
                        TextField("Name of the cookie", text: $nameCookie).onAppear() {
                          self.nameCookie = self.cookie.name
                        }
                        TextField("Type of chocolate chips for the cookie", text: $cookiesChocolateChipsType).onAppear() {
                          self.cookiesChocolateChipsType = self.cookie.style
                        }
                    }
                }
            }
        }
    }
    
}

希望能帮助您解决问题。

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