WrappedUITextView.swift

import SwiftUI
import UIKit

struct EditorView<AccessoryShelf: View>: UIViewRepresentable {
    
    // MARK: - Properties
    
    var placeholderText: String
    
    // MARK: - Binding
    
    @Binding var text: String
    @Binding var isFirstResponder: Bool
    
    // MARK: - Properties
    
    let accessoryShelf: AccessoryShelf
    let padding: CGFloat = 16
    
    /// Creates the `UITextView` instance.
    func makeUIView(context: Context) -> UITextView {
        let textView = UITextView()
        textView.delegate = context.coordinator
        
        textView.text = text
        textView.font = .rounded(ofSize: 19, weight: .regular)
        
        textView.showsVerticalScrollIndicator = false
        textView.textContainer.lineFragmentPadding = 0
        textView.textContainerInset = UIEdgeInsets(top: padding, left: padding, bottom: padding, right: padding)
        
        /// Create our placeholder string
        /// This is using a private API, so might get rejected for this...
        /// https://twitter.com/SebJVidal/status/1749162638573961383
        let placeholderAttributes: [NSAttributedString.Key: Any] = [
            .font: UIFont.rounded(ofSize: 19, weight: .regular),
            .foregroundColor: UIColor.placeholderText
        ]
        
        let attributedPlaceholderString = NSAttributedString(string: Strings.EmptyTextFieldPrompt, attributes: placeholderAttributes)
        textView.perform(NSSelectorFromString("setAttributedPlaceholder:"), with: attributedPlaceholderString)
        
        return textView
    }
    
    /// Updates the `UITextView` instance.
    func updateUIView(_ uiView: UITextView, context: Context) {
        uiView.text = text
        
        /// Handles if our `TextView` should enter
        /// focused or not.
        if isFirstResponder && !uiView.isFirstResponder {
            uiView.becomeFirstResponder()
        } else if !isFirstResponder && uiView.isFirstResponder {
            uiView.resignFirstResponder()
        }
    }
    
    /// Makes the coordinator to handle text changes.
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    class Coordinator: NSObject, UITextViewDelegate {
        var parent: EditorView
        
        init(_ parent: EditorView) {
            self.parent = parent
        }
        
        func textViewDidChange(_ textView: UITextView) {
            DispatchQueue.main.async {
                self.parent.text = textView.text
            }
        }
    }
}

private extension UIFont {
    class func rounded(ofSize size: CGFloat, weight: UIFont.Weight) -> UIFont {
        let systemFont = UIFont.systemFont(ofSize: size, weight: weight)
        let font: UIFont

        if let descriptor = systemFont.fontDescriptor.withDesign(.rounded) {
            font = UIFont(descriptor: descriptor, size: size)
        } else {
            font = systemFont
        }
        return font
    }
}