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Xcode cannot compile if there are too many modifiers

Forums > SwiftUI

I have noticed that Xcode fails to compile with

The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions

You can execute the below demo project to recreate the error. Once you uncomment confirmationDialog entries 11+ it fails to compile.

//
//  ContentView.swift
//  confDialogTest
//
//  Created by Max on 13.06.22.
//

import SwiftUI

struct ContentView: View {
    @State private var showingConf1 = false
    @State private var showingConf2 = false
    @State private var showingConf3 = false
    @State private var showingConf4 = false
    @State private var showingConf5 = false

    var body: some View {
        Button(role: .destructive) {

            self.showingConf1.toggle()
        } label: {
            Label("Conf 1", systemImage: "trash.fill")
        }
        .padding()
        Button(role: .destructive) {

            self.showingConf2.toggle()
        } label: {
            Label("Conf 2", systemImage: "trash.fill")
        }
        .padding()
        Button(role: .destructive) {

            self.showingConf3.toggle()
        } label: {
            Label("Conf 3", systemImage: "trash.fill")
        }
        .padding()
        Button(role: .destructive) {

            self.showingConf4.toggle()
        } label: {
            Label("Conf 4", systemImage: "trash.fill")
        }
        .padding()

        Button(role: .destructive) {

            self.showingConf5.toggle()
        } label: {
            Label("Conf 5", systemImage: "trash.fill")
        }
//        .padding()
        .confirmationDialog("Select location", isPresented: $showingConf1, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf2, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf3, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf4, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
            Text("Conf")
        }
        //next group is dialogs 6-10
        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
            Text("Conf")
        }
        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
            Text("Conf")
        }
        //next group is dialogs 11-15
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
        //next group is dialogs 16-20
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
//        .confirmationDialog("Select location", isPresented: $showingConf5, titleVisibility: .visible) {
//            Text("Conf")
//        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Whiel it is easy to fix here if I just move some confirmationDialogs to another Button view, I have the same problem in another problem where I have to add many modifiers to a NavigationLink in a List View and there I cannot move it around ... :/

Any ideas what to do here?

2      

The reason the modifiers stop at 10 is the same as for views in general - explanation.

You could try writing an extension, so that you can group your modifiers together in some fashion. I have added a parameter in the function, just to show that you can do this.

extension NavigationLink {

    func myNavLinkExtension(bright: Bool) -> some View {
        self.foregroundColor(Color (bright ? .orange : .gray))
            .font(.largeTitle)
    }
}

then you would use it as a normal modifier

.myNavLinkExtension(bright: false)

2      

Think I found the root cause of the issue. In my other project with the same problem, I have a structure like

Zstack{
  List{
    ForEach(sectionArray){
      Section{
        ForEach(array){
          NavigationLink{
            RowView
          }
          .confirmationDialog()
        }
      }
    }
  }
}

so I was attaching the confirmationDialog to every single NavigationLink and that seems to have killed it. Once I rearranged it to

Zstack{
  List{
    ForEach(sectionArray){
      Section{
        ForEach(array){
          NavigationLink{
            RowView
          }
        }
      }
    }
  }
}
.confirmationDialog()

the problem was gone.

2      

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