SwiftUI-更改ForEach中的结构数据集? [英] SwiftUI - Changing struct data set in ForEach?

问题描述

我是编程和SwiftUI的新手，我正在制作这个应用程序，用户可以在其中选择这些标记为A-D的按钮.他们可以选择大于1的颜色，我希望当他们单击按钮时，背景颜色将从灰色变为绿色.但是，如果我替换"//Here"，在底部的代码中，

I'm new to programming and SwiftUI and I am making this app where users can select these buttons labeled A-D. They may choose more than 1, and I am hoping that when they click on the button, the background colour will change from grey to green. However, if I replace "// Here" in the code at the bottom with

Data.Selected = true
Data.Colour = .green

我收到一条错误消息:无法分配给属性:'数据'是'let'常量".我了解这意味着什么，但我不知道如何将Data更改为var.我尝试在"Data in"前面键入var.但我却收到此错误，相反，一行上的连续语句必须用';'分隔".无论如何，我可以直接修改Data/ButtonsData吗?还是有解决方法?

I get an error saying "Cannot assign to property: 'Data' is a 'let' constant". I understand what that means, but I don't know how to change Data to var. I tried typing var in front of "Data in" but I got this error instead "Consecutive statements on a line must be separated by ';'". Is there anyway I can directly modify Data/ButtonsData? Or is there a workaround?

struct Buttons: Hashable {
    var Crit: String
    var Selected: Bool
    var Colour: Color
}

var ButtonsData = [
    Buttons(Crit: "A", Selected: false, Colour: Color(.systemGray4)),
    Buttons(Crit: "B", Selected: false, Colour: Color(.systemGray4)),
    Buttons(Crit: "C", Selected: false, Colour: Color(.systemGray4)),
    Buttons(Crit: "D", Selected: false, Colour: Color(.systemGray4))
]

struct CritView: View {
    
    @Binding var CritBoard: Bool
    @Binding var BackgroundColor: Color
    
    var body: some View {
        ZStack(alignment: .topLeading) {
            
            ScrollView(.vertical, showsIndicators: false) {
                HStack(spacing: 15) {
                    ForEach(ButtonsData, id: \.self) { Data in
                        Button(action: {
                          // HERE
                        }) {
                            Text(Data.Crit)
                                .font(.system(size: 30))
                        }
                        .frame(width: 65, height: 55)
                        .background(Data.Colour)
                        .cornerRadius(10)
                    }
                }
                .padding(.top, 50)
            }
            .frame(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height/8)
            .padding(.bottom, UIApplication.shared.windows.first?.safeAreaInsets.bottom)
            .background(Color(.white))
            .cornerRadius(25)
            
            Button(action: {
                self.CritBoard.toggle()
                self.BackgroundColor = .white
            }) {
                Image(systemName: "xmark").foregroundColor(.black)
            }.padding(25)
        }
    }
}

推荐答案

好吧，我认为很多人实际上不会遇到相同/相似的问题，但这是我的工作代码.该代码同时使用@Aspersi的答案以及用Swift黑客"一文中的代码.(它可能不是最简化的代码，但至少现在就可以使用)

Well, I don't think a lot of people would actually have the same/similar problem but this is my working code. The code uses both @Aspersi's answer as well as the code in a Hacking with Swift article. (it might not be the most simplified code, but it works right now at least)

ForEach(Array(ButtonsData.enumerated()), id: \.element) { i, Data in
    Button(action: {
        self.AllData[i].Selected.toggle()
        if self.AllData[i].Selected == true {
            self.AllData[i].Colour = .green
        } else {
            self.AllData[i].Colour = Color(.systemGray4)
        }
    }) {
        Text(Data.Crit)
            .font(.system(size: 30))
    }
    .frame(width: 65, height: 55)
    .background(self.AllData[i].Colour)
    .cornerRadius(10)
}

下面的完整代码

struct Buttons: Hashable {
    var Crit: String
    var Selected: Bool = false
    var Colour: Color
}

var ButtonsData = [
    Buttons(Crit: "A", Selected: false, Colour: Color(.systemGray4)),
    Buttons(Crit: "B", Selected: false, Colour: Color(.systemGray4)),
    Buttons(Crit: "C", Selected: false, Colour: Color(.systemGray4)),
    Buttons(Crit: "D", Selected: false, Colour: Color(.systemGray4))
]

struct CritView: View {
    
    @Binding var CritBoard: Bool
    @Binding var BackgroundColor: Color
    
    @State private var AllData = ButtonsData
    
    var body: some View {
        ZStack(alignment: .topLeading) {
            
            ScrollView(.vertical, showsIndicators: false) {
                HStack(spacing: 15) {
                    ForEach(Array(ButtonsData.enumerated()), id: \.element) { I, Data in
                        Button(action: {
                            self.AllData[i].Selected.toggle()
                            if self.AllData[i].Selected == true {
                                self.AllData[i].Colour = .green
                            } else {
                                self.AllData[i].Colour = Color(.systemGray4)
                            }
                        }) {
                            Text(Data.Crit)
                                .font(.system(size: 30))
                        }
                        .frame(width: 65, height: 55)
                        .background(self.AllData[i].Colour)
                        .cornerRadius(10)
                    }
                }
                .padding(.top, 50)
            }
            .frame(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height/8)
            .padding(.bottom, UIApplication.shared.windows.first?.safeAreaInsets.bottom)
            .background(Color(.white))
            .cornerRadius(25)
            
            Button(action: {
                self.CritBoard.toggle()
                self.BackgroundColor = .white
            }) {
                Image(systemName: "xmark").foregroundColor(.black)
            }.padding(25)
        }
    }
}

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