WrappedUITextField

WrappedUITextField.swift

import SwiftUI
import UIKit

/*
This is how I've used UIViewRepresentable for wrapping a UITextField
for the Search input of my app Daypage.

Usage:

SearchInputView(
    placeholderText: Strings.SearchInputPrompt,
    searchQuery: $searchQuery,
    isFirstResponder: $isFirstResponder
)

For my specific use case, I've chosen to make `isFirstResponder`
a binding, so I can let the parent view inform if this field should
be focussed when the view appears or not, like so:

@State private var isFirstResponder: Bool = true
*/

struct SearchInputView: UIViewRepresentable {
    
    // MARK: - Properties
    
    var placeholderText: String
    
    // MARK: - Binding
    
    @Binding var searchQuery: String
    @Binding var isFirstResponder: Bool
    
    func makeUIView(context: Context) -> UITextField {
        let textField = UITextField()
        textField.delegate = context.coordinator
        
        textField.placeholder = placeholderText
        textField.text = searchQuery
        textField.returnKeyType = .search
        
        return textField
    }
    
    /// Makes the view act closer to a SwiftUI
    /// view in terms of respecting the size
    /// of it's parent container.
    func sizeThatFits(
        _ proposal: ProposedViewSize,
        uiView: UITextField, context: Context
    ) -> CGSize? {
        guard
            let width = proposal.width,
            let height = proposal.height
        else { return nil }
        
        return CGSize(width: width, height: height)
    }
    
    /// Updates the `UITextField` instance.
    func updateUIView(_ uiView: UITextField, context: Context) {
        uiView.text = searchQuery
        
        /// Handles if our `TextView` should enter
        /// focused or not.
        if isFirstResponder {
            uiView.becomeFirstResponder()
        }
    }
    
    /// Makes the coordinator to handle text changes.
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    class Coordinator: NSObject, UITextFieldDelegate {
        var parent: SearchInputView
        
        init(_ parent: SearchInputView) {
            self.parent = parent
        }
        
        func textFieldDidChangeSelection(_ textField: UITextField) {
            /// By using `DispatchQueue.main.async` we ensure that the update to
            /// `searchQuery` occurs after the current cycle of view updates completes,
            /// avoiding the modification of state during a view update.
            DispatchQueue.main.async {
                self.parent.searchQuery = textField.text ?? ""
            }
        }
        
        func textFieldShouldReturn(_ textField: UITextField) -> Bool {
            textField.resignFirstResponder() // Dismiss the keyboard
            return true
        }
    }
}