LargeTitles UIScrollView does not support multiple observers implementing _scrollViewWillEndDraggingWithVelocity:targetContentOffset

Question

I have implemented large titles in my app with the following code:

if #available(iOS 11.0, *) {
            navigationController?.navigationBar.prefersLargeTitle         


        

Answer 1

This is not a solution, but a potential thing that you need to investigate in your code. I got this same error message (UIScrollView does not support multiple observers implementing _scrollViewWillEndDraggingWithVelocity:targetContentOffset) and I noticed I was doing something incorrectly. I got this error message in a SwiftUI app using NavigationView.

The mistake I had made was that ParentView had a Navigation View at the root. Using a NavigationLink I was moving to ChildView, which also had a NavigationView as the root. Here's what it looked like in code:

import SwiftUI

@main
struct TestApp: App {
    var body: some Scene {
        WindowGroup {
            ParentView()
        }
    }
}

struct ParentView: View {
    var body: some View {
        NavigationView {
            List {
                NavigationLink(destination: ChildView()) {
                    Text("Parent view")
                }
            }
            .navigationTitle("Parent")
        }
    }
}

struct ChildView: View {
    var body: some View {
        List {
            ForEach(0 ..< 5) { _ in
                Text("Child view")
            }
        }
        .navigationTitle("Child")
    }
}

Initially this is what ChildView looked like:

struct ChildView: View {
    var body: some View {
        NavigationView {
            List {
                ForEach(0 ..< 5) { _ in
                    Text("Second screen")
                }
            }
            .navigationTitle("Second")
        }
    }
}

Notice how I was trying to push a view which itself was embedded in a NavigationView. Removing it as shown in the first snippet, took care of the error messages. You can try looking into that, maybe you are doing the same mistake just in UIKit instead of SwiftUI.