SwiftUI UITextView jumps to the top when typing and text wraps to a new line

Question

I have a custom UITextView wrapped in SwiftUI using UIViewRepresentable. The goal is to have a dynamic height text view that grows as the user types. Here is a simplified version of my code:

    import SwiftUI

struct ContentView: View {
    @State private var text = populateText()
    @State private var minHeight: CGFloat = 36
    private let lineLimit: Int = 0

    var body: some View {
        NavigationStack {
            ScrollView {
                DynamicTextView(
                    text: $text,
                    font: UIFont.systemFont(ofSize: 16),
                    linesLimit: lineLimit
                )
                .frame(minHeight: minHeight)
                .overlay {
                    RoundedRectangle(cornerRadius: 8)
                        .stroke(Color.gray, lineWidth: 1)
                }
                .padding()
            }
        }
    }
}

struct DynamicTextView: UIViewRepresentable {
    @Binding var text: String
    
    let font: UIFont
    let linesLimit: Int
    
    private var isScrollEnabled: Bool {
        linesLimit > .zero ? true : false
    }
    
    func makeUIView(context: Context) -> UITextView {
        let textView = CustomTextView()
        textView.delegate = context.coordinator
        textView.font = font
        textView.text = text
        textView.backgroundColor = .clear
        textView.textContainer.lineFragmentPadding = 0
        textView.textContainerInset = .init(top: 8, left: 8, bottom: 8, right: 8)
        textView.isScrollEnabled = isScrollEnabled
        return textView
    }
    
    func updateUIView(_ uiView: UITextView, context: Context) {
        if uiView.text != text {
            uiView.text = text
        }
    }
    
    func sizeThatFits(_ proposal: ProposedViewSize, uiView: UITextView, context: Context) -> CGSize? {
        let width = proposal.width ?? uiView.bounds.width
        
        let fitting = CGSize(width: width, height: .greatestFiniteMagnitude)
        let calculatedHeight = uiView.sizeThatFits(fitting).height
        
        var height = calculatedHeight

        if linesLimit > 0 {
            let lineHeight = font.lineHeight
            let maxHeight = lineHeight * CGFloat(linesLimit) + uiView.textContainerInset.top + uiView.textContainerInset.bottom
            height = min(maxHeight, calculatedHeight)
        }
                
        return CGSize(width: width, height: height)
    }
    
    func makeCoordinator() -> Coordinator {
        Coordinator(text: $text)
    }
    
    class Coordinator: NSObject, UITextViewDelegate {
        @Binding var text: String
        
        init(text: Binding<String>) {
            self._text = text
        }
        
        func textViewDidChange(_ textView: UITextView) {
            text = textView.text
        }
    }
}

final class CustomTextView: UITextView {
    init() {
        super.init(frame: .zero, textContainer: nil)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

#Preview {
    ContentView()
}

func populateText() -> String {
    var text = ""
     for _ in 0..<300 {
         text += " Large text"
    }
    return text
}

The issue:

When typing a long text, if the system automatically wraps text to a new line, the entire text content jumps back to the top for a moment. The caret remains in the correct place on the new line. If I press Enter to insert a manual line break, the issue does not happen. When I continue typing, the text returns to the correct position, but the jumping is very noticeable.

Question:

Why does UITextView inside SwiftUI jump to the top when the text wraps to a new line, and how can I fix this so the text stays stable while typing?

What the bug looks like.

Coordinator(self) won’t work cause the representable is a value with no lifetime not an object, where did you get that from? — malhal
– malhal, Commented Sep 12 at 10:59
Yes, you’re right. I’ve edited the code in the example. But the problem remains. — Ivan Magda
– Ivan Magda, Commented Sep 12 at 11:50
That edit won't work if the representable is init again with a new binding because makeCoordinator is only called on the first init. — malhal
– malhal, Commented Sep 13 at 21:46

Dixit Akabari · Accepted Answer · 2025-09-12 11:52:17Z

Avoid forcing layout recalculations on every update and let UITextView report its intrinsic content size. Combine this with .fixedSize(horizontal: false, vertical: true) in SwiftUI and preserve the selection/scroll position when updating.

Try This One :

import SwiftUI
import UIKit

struct ContentView: View {
    @State private var text = populateText()
    
    var body: some View {
        NavigationStack {
            ScrollView {
                DynamicTextView(
                    text: $text,
                    font: UIFont.systemFont(ofSize: 16),
                    linesLimit: 0 // 0 = unlimited
                )
                .fixedSize(horizontal: false, vertical: true) // 👈 expands dynamically
                .overlay {
                    RoundedRectangle(cornerRadius: 8)
                        .stroke(Color.gray, lineWidth: 1)
                }
                .padding()
            }
        }
    }
}

// MARK: - UIViewRepresentable wrapper
struct DynamicTextView: UIViewRepresentable {
    @Binding var text: String
    let font: UIFont
    let linesLimit: Int
    
    private var isScrollEnabled: Bool {
        linesLimit > 0
    }
    
    func makeUIView(context: Context) -> UITextView {
        let textView = CustomTextView()
        textView.delegate = context.coordinator
        textView.font = font
        textView.text = text
        textView.backgroundColor = .clear
        textView.textContainer.lineFragmentPadding = 0
        textView.textContainerInset = .init(top: 8, left: 8, bottom: 8, right: 8)
        textView.isScrollEnabled = isScrollEnabled
        return textView
    }
    
    func updateUIView(_ uiView: UITextView, context: Context) {
        // Only update if text changed (prevents jump)
        guard uiView.text != text else { return }
        let selectedRange = uiView.selectedRange
        uiView.text = text
        uiView.selectedRange = selectedRange
        uiView.scrollRangeToVisible(selectedRange)
    }
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    class Coordinator: NSObject, UITextViewDelegate {
        var parent: DynamicTextView
        
        init(_ parent: DynamicTextView) {
            self.parent = parent
        }
        
        func textViewDidChange(_ textView: UITextView) {
            parent.text = textView.text
        }
    }
}

// MARK: - Custom TextView with intrinsic size
final class CustomTextView: UITextView {
    override var intrinsicContentSize: CGSize {
        let fittingSize = CGSize(width: bounds.width, height: .greatestFiniteMagnitude)
        let size = sizeThatFits(fittingSize)
        return CGSize(width: UIView.noIntrinsicMetric, height: size.height)
    }
    
    init() {
        super.init(frame: .zero, textContainer: nil)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

#Preview {
    ContentView()
}

// MARK: - Sample long text
func populateText() -> String {
    var text = ""
    for _ in 0..<30 {
        text += " Large text"
    }
    return text
}

Thank you for your response, but it didn’t help. I’ve added a description of what the bug looks like visually.

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