How to add a first responder to a multi line text field - swiftui

Question

I have a multi line text field, and need it to become a first responder when it appears. Also, it needs to resign as a first responder when the onCommit parameter of MultiLineTextField is fired, or one of 2 buttons are tapped.
As it stands, the keyboard dismisses when it should but immediately reappears when it shouldn't.
I know I could just use the new iOS 16 TextField .axis parameter, but I need to stick with iOS 15.5, hence the long drawn out code below.
import SwiftUI
struct MultilineTextField: View {
private var placeholder: String
private var onCommit: (() -> Void)?
#State private var viewHeight: CGFloat = 40 //start with one line
#State private var shouldShowPlaceholder = false
#Binding private var text: String
private var internalText: Binding<String> {
Binding<String>(get: { self.text } ) {
self.text = $0
self.shouldShowPlaceholder = $0.isEmpty
}
}
var body: some View {
UITextViewWrapper(text: self.internalText, calculatedHeight: $viewHeight, onDone: onCommit)
.frame(minHeight: viewHeight, maxHeight: viewHeight)
.background(placeholderView, alignment: .topLeading)
}
var placeholderView: some View {
Group {
if shouldShowPlaceholder {
Text(placeholder).foregroundColor(.gray)
.padding(.leading, 4)
.padding(.top, 8)
}
}
}
init (_ placeholder: String = "", text: Binding<String>, onCommit: (() -> Void)? = nil) {
self.placeholder = placeholder
self.onCommit = onCommit
self._text = text
self._shouldShowPlaceholder = State<Bool>(initialValue: self.text.isEmpty)
}
}
private struct UITextViewWrapper: UIViewRepresentable {
typealias UIViewType = UITextView
#Binding var text: String
#Binding var calculatedHeight: CGFloat
var onDone: (() -> Void)?
func makeUIView(context: UIViewRepresentableContext<UITextViewWrapper>) -> UITextView {
let textField = UITextView()
textField.delegate = context.coordinator
textField.isEditable = true
textField.font = UIFont.preferredFont(forTextStyle: .body)
textField.isSelectable = true
textField.isUserInteractionEnabled = true
textField.autocorrectionType = .no
textField.isScrollEnabled = false
textField.backgroundColor = UIColor.clear
textField.keyboardType = .asciiCapable
textField.textColor = .systemBlue
textField.textAlignment = .center
if nil != onDone {
textField.returnKeyType = .done
}
textField.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
return textField
}
func updateUIView(_ uiView: UITextView, context: UIViewRepresentableContext<UITextViewWrapper>) {
if uiView.text != self.text {
uiView.text = self.text
}
if uiView.window != nil, !uiView.isFirstResponder {
uiView.becomeFirstResponder()
}
UITextViewWrapper.recalculateHeight(view: uiView, result: $calculatedHeight)
}
private static func recalculateHeight(view: UIView, result: Binding<CGFloat>) {
let newSize = view.sizeThatFits(CGSize(width: view.frame.size.width, height: CGFloat.greatestFiniteMagnitude))
if result.wrappedValue != newSize.height {
DispatchQueue.main.async {
result.wrappedValue = newSize.height // call in next render cycle.
}
}
}
func makeCoordinator() -> Coordinator {
return Coordinator(text: $text, height: $calculatedHeight, onDone: onDone)
}
final class Coordinator: NSObject, UITextViewDelegate {
var text: Binding<String>
var calculatedHeight: Binding<CGFloat>
var onDone: (() -> Void)?
init(text: Binding<String>, height: Binding<CGFloat>, onDone: (() -> Void)? = nil) {
self.text = text
self.calculatedHeight = height
self.onDone = onDone
}
func textViewDidChange(_ uiView: UITextView) {
text.wrappedValue = uiView.text
UITextViewWrapper.recalculateHeight(view: uiView, result: calculatedHeight)
}
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if let onDone = self.onDone, text == "\n" {
textView.resignFirstResponder()
onDone()
return false
}
return true
}
}
}
MultilineTextField Usage:
MultilineTextField("", text: Binding<String>(
get: { userAnswer },
set: {
self.userAnswer = $0.allowedCharacters(string: $0)
self.enableHint()
}), onCommit: {
if self.userAnswer.isEmpty {
nativeForeignPlaceholder = NSMutableAttributedString(string: "Tap here to answer...")
} else {
answerDisabled = true
checkAnswer()
}
})
.overlay(RoundedRectangle(cornerRadius: 5).stroke(Color.systemBlue, lineWidth: overlayLineWidth))
.modifier(TextFieldClearButton(text: $userAnswer))
.placeholder(when: userAnswer.isEmpty) {
TextWithAttributedString(attributedString: nativeForeignPlaceholder ?? NSMutableAttributedString())
}
.font(.system(size: fontSize, weight: .regular, design: .rounded))
.lineLimit(2)
.disabled(answerDisabled)
.onAppear {
// key part: delay setting isFocused until after some-internal-iOS setup
DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
answerIsFocused = true
}
}
.onTapGesture(perform: tapOnAnswerField)
.frame(dynamicWidth: 675, dynamicHeight: 100, alignment: .center)
.position(x: geometry.frame(in: .local).midX, y: geometry.frame(in: .local).midY + geometry.size.height / 8.5)
func tapOnAnswerField() {
answerIsFocused = true
}