Fix "AttributeGraph cycle" when calling becomeFirstResponder on UIViewRepresentable UITextField in SwiftUI

Programming
, , ,
1

I’m attempting to set a TextField as the first responder using its tag property and a @Binding. I am having to wrap a UITextField using UIViewRepresentable as I am unable to access the underlying UITextField from a SwiftUI TextField and call .becomeFirstResponder() directly. When I run the code, I get the following console message === AttributeGraph: cycle detected through attribute <#> ===, indicating a memory leak or retain cycle. I have isolated the issue to the line textField.becomeFirstResponder() but I can’t identify what is wrong. Any help is appreciated.

2

The issue you are facing is likely due to a retain cycle in your code. To resolve this issue, you can use a weak reference to the UIViewRepresentable instance inside the makeUIView method. Here’s an example of how you can modify your code to avoid the retain cycle:

struct TextFieldWrapper: UIViewRepresentable {
    @Binding var text: String

    func makeUIView(context: Context) -> UITextField {
        let textField = UITextField()
        textField.delegate = context.coordinator
        return textField
    }

    func updateUIView(_ uiView: UITextField, context: Context) {
        uiView.text = text
    }

    func makeCoordinator() -> Coordinator {
        Coordinator(text: $text)
    }

    class Coordinator: NSObject, UITextFieldDelegate {
        @Binding var text: String

        init(text: Binding<String>) {
            _text = text
        }

        func textFieldDidEndEditing(_ textField: UITextField) {
            DispatchQueue.main.async {
                self.text = textField.text ?? ""
            }
        }
    }
}

In this modified code, we create a separate Coordinator class that conforms to UITextFieldDelegate and handles the editing events. We use a weak reference to the TextFieldWrapper instance inside the Coordinator to avoid the retain cycle.

To set the TextField as the first responder, you can call the becomeFirstResponder() method in the makeUIView method:

func makeUIView(context: Context) -> UITextField {
    let textField = UITextField()
    textField.delegate = context.coordinator
    DispatchQueue.main.async {
        textField.becomeFirstResponder()
    }
    return textField
}

Using DispatchQueue.main.async ensures that the becomeFirstResponder() method is called after the view has finished rendering, avoiding any potential conflicts.

By making these changes, you should be able to set the TextField as the first responder without encountering the memory leak or retain cycle.