SwiftUI TabView - run code in subview after sequential taps-CodePudding

I am trying to implement the behavior in a TabView when the user taps the same tab multiple times, such as in the iOS AppStore app. First tap: switch to that view, second tap: pop to root, third tap: scroll to the top if needed.

The code below works fine for switching and didTap() is called for every tap.

import SwiftUI

enum Tab: String {
    case one
    case two
}

struct AppView: View {
    @State private var activeTab = Tab.one

    var body: some View {
        TabView(selection: $activeTab.onChange(didTap)) {
            One()
                .tabItem {
                    Label("one", systemImage: "1.lane")
                }
                .tag(Tab.one)

            Two()
                .tabItem {
                    Label("two", systemImage: "2.lane")
                }
                .tag(Tab.two)
        }
    }
    
    func didTap(to value: Tab) {
        print(value) // this captures every tap
    }
}

extension Binding {
    func onChange(_ handler: @escaping (Value) -> Void) -> Binding<Value> {
        Binding(
            get: { self.wrappedValue },
            set: { newValue in
                self.wrappedValue = newValue
                handler(newValue)
            }
        )
    }
}

What I am struggling with, is how to tell either One or Two that it was tapped for a second or third time? (How to pop and scroll is not the issue).

I have seen this: TabView, tabItem: running code on selection or adding an onTapGesture but it doesn't explain how to run code in one of the views.

Any suggestions?

CodePudding user response：

You can record additional taps (of same value) in an array. The array count gives you the number of taps on the same Tab.

EDIT: now with explicit subview struct.

struct ContentView: View {
    
    @State private var activeTab = Tab.one

    @State private var tapState: [Tab] = [Tab.one] // because .one is default
    
    var body: some View {
        TabView(selection: $activeTab.onChange(didTap)) {
            
            SubView(title: "One", tapCount: tapState.count)
                .tabItem {
                    Label("one", systemImage: "1.lane")
                }
                .tag(Tab.one)

            SubView(title: "Two", tapCount: tapState.count)
                .tabItem {
                    Label("two", systemImage: "2.lane")
                }
                .tag(Tab.two)
        }
    }
    
    func didTap(to value: Tab) {
        print(value) // this captures every tap
        if tapState.last == value {
            tapState.append(value) // apped next tap if same value
            print("tapped \(tapState.count) times")
        } else {
            tapState = [value] // reset tap state to new tab selection
        }
    }
}


struct SubView: View {
    
    let title: String
    let tapCount: Int
    
    var body: some View {
        VStack {
            Text("Subview \(title)").font(.title)
            Text("tapped \(tapCount) times")
        }
    }
}