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Xcode – how can I refresh another cell when change observedObject

UfukK246ker
March 12, 2021
158 views
2 votes
3 Answers

When I select a cell, I want to deselect it from the other cell. After making the selection, I cannot remove the selection from the previous cell. What is the reason of this ? Sorry. I know little English.

Enum

enum Page {
    case newest
    case populer
    case iPhone
    case iPad
    case mac
    case watch
}

ViewModel

class MainViewModel: ObservableObject {
    @Published var selectedTab = Page.newest
}

Category Model

struct Category: Identifiable {
    var id = UUID()
    var title: String
    var icon: String
    var color: Color
    var page: Page
}

Basic Category

let basicCategory = [
    Category(title: "En Yeniler", icon: "flame", color: .red, page: .newest),
    Category(title: "Popüler", icon: "star", color: .yellow, page: .populer),
]

Cell

struct TabView: View {
    var title: String = ""
    var icon: String = ""
    var color: Color
     var page: Page
    @ObservedObject var macMainVM = MainViewModel()
    var body: some View {
        
        Button(action: {
            withAnimation(.spring(response: 0.5, dampingFraction: 0.6, blendDuration: 0)) {
                
                self.macMainVM.selectedTab = self.page
            }
        }) {
            VStack {
                Image(systemName: icon)
                    .imageScale(.large)
                    .foregroundColor(color)
                Text(title)
                    .font(.custom("Oswald-Light", size: 14))
                    .fixedSize()
            }
            .padding(5)
//I emphasize the choice here
            .background(self.macMainVM.selectedTab == self.page ? RoundedRectangle(cornerRadius: 10).stroke(color) : nil)
            
        }
        .buttonStyle(PlainButtonStyle())
    }
}

ForEach

VStack {
   ForEach(basicCategory, id: .id) { item in
     TabView(title: item.title, icon: item.icon, color: item.color, page: item.page)
                }
            }

Answers

Updated my answer with the working answer.

The problem was that you were using @ObservedObject instead of a @StateObject

Always use @StateObject for the parent view and @ObservedObject for the children view.

import SwiftUI

struct stackT: View {
   @StateObject var macMainVM = MainViewModel()
    var body: some View {
        VStack {
           ForEach(basicCategory, id: .id) { item in
            TabView(macMainVM: macMainVM, title: item.title, icon: item.icon, color: item.color, page: item.page)
                        }
                    }
    }
}

struct stackT_Previews: PreviewProvider {
    static var previews: some View {
        stackT()
    }
}


struct TabView: View {
    @ObservedObject var macMainVM: MainViewModel
    var title: String = ""
    var icon: String = ""
    var color: Color
    let page: Page
    var body: some View {
        
        Button(action: {
            withAnimation(.spring(response: 0.5, dampingFraction: 0.6, blendDuration: 0)) {
                DispatchQueue.main.async {
                    self.macMainVM.globalTab = page
                    print(macMainVM.globalTab)
                }
            }
        }) {
            VStack {
                Image(systemName: icon)
                    .imageScale(.large)
                    .foregroundColor(color)
                Text(title)
                    .font(.custom("Oswald-Light", size: 14))
                    .fixedSize()
            }
            .padding(5)
//I emphasize the choice here
            .background(self.macMainVM.globalTab == self.page ? RoundedRectangle(cornerRadius: 10).stroke(color) : RoundedRectangle(cornerRadius: 10).stroke(.clear))
            
        }
        .buttonStyle(PlainButtonStyle())
    }
}

class MainViewModel: ObservableObject {
    @Published var globalTab = Page.newest

}


enum Page {
    case newest
    case populer
    case iPhone
    case iPad
    case mac
    case watch
    case none
}

struct Category: Identifiable {
    var id = UUID()
    var title: String
    var icon: String
    var color: Color
    var page: Page
}

let basicCategory = [
    Category(title: "En Yeniler", icon: "flame", color: .red, page: .newest),
    Category(title: "Popüler", icon: "star", color: .yellow, page: .populer),
    Category(title: "Another", icon: "book", color: .blue, page: .mac)
]

Below are the approaches for single selection and multiple selection.

For single selection you can pass Page as Bindings to subView.
For multiple selection you can maintain a boolean state array, that can tell if current cell was already selected or not.

Single Selection

import SwiftUI

enum Page:String {
    case newest
    case populer
    case iPhone
    case iPad
    case mac
    case watch
}

struct Category: Identifiable {
    var id = UUID()
    var title: String
    var icon: String
    var color: Color
    var page: Page
}

class MainViewModel: ObservableObject {
    @Published var selectedTab = Page.newest
}

struct TabView: View {
    var title: String = ""
    var icon: String = ""
    var color: Color = .red
    var page: Page
    @Binding var macMainVM :Page
    
    
    var body: some View {
        
        Button(action: {
            withAnimation(.spring(response: 0.5, dampingFraction: 0.6, blendDuration: 0)) {
                
                self.macMainVM = self.page
            }
        }) {
            VStack {
                
                Text("Tap")
                    .font(.custom("Oswald-Light", size: 14))
                    .fixedSize()
            }
            .padding(5)
            //I emphasize the choice here
            .background(self.macMainVM == self.page ? RoundedRectangle(cornerRadius: 10).stroke(color) : nil)
            
        }
        .buttonStyle(PlainButtonStyle())
    }
}

struct mainView:View{
    
    let basicCategory = [
        Category(title: "En Yeniler", icon: "flame", color: .red, page: .newest),
        Category(title: "Popüler", icon: "star", color: .yellow, page: .populer),
    ]
    
    @ObservedObject var macMainVM = MainViewModel()
    
    var body: some View {
        VStack {
            ForEach(basicCategory.indices) { index in
                TabView(page: basicCategory[index].page,macMainVM: $macMainVM.selectedTab)
            }
        }
    }
}

Multiple Selection

   import SwiftUI

enum Page:String {
    case newest
    case populer
    case iPhone
    case iPad
    case mac
    case watch
}


class MainViewModel: ObservableObject {
    @Published var selectedTab = Page.newest
    var stateArray:[Bool] = []
}

struct Category: Identifiable {
    var id = UUID()
    var title: String
    var icon: String
    var color: Color
    var page: Page
}

struct TabView: View {

    var title: String = ""
    var icon: String = ""
    var color: Color = Color.red

    var page: Page
    var count = 0
    var onIndex:Int

    @ObservedObject var macMainVM = MainViewModel()

    init(totalPage:Int,page:Page,onIndex:Int) {
        self.count = totalPage
        self.page = page
        self.onIndex = onIndex
        macMainVM.stateArray = [Bool](repeating: false, count: totalPage)
    }

    var body: some View {

        Button(action: {
            withAnimation(.spring(response: 0.5, dampingFraction: 0.6, blendDuration: 0)) {

                if macMainVM.stateArray[onIndex] == false{
                    macMainVM.stateArray[onIndex] = true
                }else{
                    macMainVM.stateArray[onIndex] = false
                }

                macMainVM.selectedTab = self.page

            }
        }) {
            VStack {

                Text("Tap")
                    .font(.custom("Oswald-Light", size: 14))
                    .fixedSize()
            }
            .padding(5)
            //I emphasize the choice here
            .background(macMainVM.stateArray[onIndex] ? RoundedRectangle(cornerRadius: 10).stroke(color) : nil)

        }
        .buttonStyle(PlainButtonStyle())
    }
}

struct mainView:View{
    let basicCategory = [
        Category(title: "En Yeniler", icon: "flame", color: .red, page: .newest),
        Category(title: "Popüler", icon: "star", color: .yellow, page: .populer),
    ]
    //var model = MainViewModel()
    var body: some View {
        VStack {
            ForEach(basicCategory.indices) { index in
                TabView(totalPage: basicCategory.count, page: basicCategory[index].page, onIndex: index)
            }
        }
    }
}

NOTE-: I haven’t explained what I did in deep, because it will be more understandable by looking into code.

The most Easy way: You should just use shared object, which you are creating new one every time! I did not edit your code! I just used a shared model! that was all I done! Or you can use environmentObject, and that would also solve the issue without shared one! both way is working!

import SwiftUI
        
 struct ContentView: View {
            

    var body: some View {
    
            VStack {
                ForEach(basicCategory, id: .id) { item in
                    TabView(title: item.title, icon: item.icon, color: item.color, page: item.page)
                }
            }
            .background(Color.gray)
            
        }
    }
    
    
    enum Page {
        case newest
        case populer
        case iPhone
        case iPad
        case mac
        case watch
    }
    
    class MainViewModel: ObservableObject {
        
        static let shared: MainViewModel = MainViewModel() // <<: Here
        
        @Published var selectedTab = Page.newest
        
    }
    
    
    struct Category: Identifiable {
        
        var id = UUID()
        var title: String
        var icon: String
        var color: Color
        var page: Page
        
    }
    
    
    
    let basicCategory = [
        Category(title: "En Yeniler", icon: "flame", color: .red, page: .newest),
        Category(title: "Popüler", icon: "star", color: .yellow, page: .populer),
        Category(title: "iPhone", icon: "iphone.homebutton", color: .yellow, page: .iPhone),
        Category(title: "ipad", icon: "ipad.homebutton", color: .yellow, page: .iPad),
    ]
    
    
    struct TabView: View {
        
        let title: String
        let icon: String
        let color: Color
        let page: Page
        
        @ObservedObject var macMainVM = MainViewModel.shared // <<: Here
        
        
        var body: some View {
            
            
            
            Button(action: {
                
                withAnimation(.spring(response: 0.5, dampingFraction: 0.6, blendDuration: 0)) {
                    
                    macMainVM.selectedTab = page
                    
                }
            }) {
                
                VStack {
                    Image(systemName: icon)
                        .imageScale(.large)
                        .foregroundColor(color)
                    Text(title)
                        .font(.custom("Oswald-Light", size: 14))
                        .fixedSize()
                }
                .padding(5)
                .background(macMainVM.selectedTab == page ? RoundedRectangle(cornerRadius: 10).stroke(color) : nil)
                
            }
            .buttonStyle(PlainButtonStyle())
            
            
            
        }
    }

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