Experimental library for creating useful TextFieldStyles in SwiftUI.

!BetterTextFieldStyle.md

Install via SPM per usual. Supports iOS 13+. MIT License.

_Public.swift

import SwiftUI
import Introspect

public protocol BetterTextFieldStyle: TextFieldStyle {}

extension View {
  public func textFieldStyle<S: BetterTextFieldStyle>(_ style: S) -> some View {
    textFieldStyle(CombinedStyle(style))
  }
}

@propertyWrapper
public struct TextFieldState<Value>: DynamicProperty {

  @Environment(\.textFieldState)
  private var state

  private let keyPath: KeyPath<FieldState, Value>

  public init() where Value == FieldState {
    self.keyPath = \.self
  }

  public init(_ keyPath: KeyPath<FieldState, Value>) {
    self.keyPath = keyPath
  }

  public var wrappedValue: Value {
    get { state[keyPath: keyPath] }
  }
}

public struct FieldState {
  public var isEditing: Bool = false
  public var text: Binding<String>

  struct Key: EnvironmentKey {
    static var defaultValue: FieldState = .init(text: .constant(""))
  }
}

Internal.swift

import SwiftUI

extension EnvironmentValues {
  var textFieldState: FieldState {
    get { self[FieldState.Key.self] }
    set { self[FieldState.Key.self] = newValue }
  }
}

struct CombinedStyle<S: TextFieldStyle>: TextFieldStyle {
  let style: S

  init(_ style: S) {
    self.style = style
  }

  func _body(configuration: TextField<_Label>) -> some View {
    configuration
      .textFieldStyle(CoordinatorStyle())
      .textFieldStyle(style)
  }
}

struct CoordinatorStyle: TextFieldStyle {

  @StateObject
  private var coordinator = Coordinator()

  func _body(configuration: TextField<_Label>) -> some View {
    configuration
      .environment(\.textFieldState, .init(
        isEditing: coordinator.isEditing,
        text: Mirror(reflecting: configuration).descendant("_text") as! Binding<String>)
      )
      .introspectTextField { textField in
        coordinator.textField = textField
      }
  }

  class Coordinator: NSObject, ObservableObject, UITextFieldDelegate {

    @Published
    private(set) var isEditing: Bool = false

    weak var textField: UITextField? {
      didSet {
        if delegate == nil, let delegate = textField?.delegate {
          self.delegate = delegate
          textField?.delegate = self
        }
      }
    }

    weak var delegate: UITextFieldDelegate?

    func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool  {
      delegate?.textFieldShouldBeginEditing?(textField) ?? true
    }

    func textFieldDidBeginEditing(_ textField: UITextField) {
      isEditing = true
      delegate?.textFieldDidBeginEditing?(textField)
    }

    func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
      delegate?.textFieldShouldEndEditing?(textField) ?? true
    }

    func textFieldDidEndEditing(_ textField: UITextField) {
      isEditing = false
      delegate?.textFieldDidEndEditing?(textField)
    }

    func textFieldDidEndEditing(_ textField: UITextField, reason: UITextField.DidEndEditingReason) {
      isEditing = false
      delegate?.textFieldDidEndEditing?(textField, reason: reason)
    }

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
      delegate?.textField?(textField, shouldChangeCharactersIn: range, replacementString: string) ?? true
    }

    func textFieldDidChangeSelection(_ textField: UITextField) {
      delegate?.textFieldDidChangeSelection?(textField)
    }

    func textFieldShouldClear(_ textField: UITextField) -> Bool {
      delegate?.textFieldShouldClear?(textField) ?? false
    }

    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
      delegate?.textFieldShouldReturn?(textField) ?? true
    }
  }
}

Package.swift

// swift-tools-version: 5.6

import PackageDescription

let package = Package(
  name: "swiftui-better-textfieldstyle",
  platforms: [.iOS(.v13)],
  products: [
    .library(
      name: "BetterTextFieldStyle",
      targets: ["BetterTextFieldStyle"]),
  ],
  dependencies: [
    .package(url: "https://github.com/siteline/SwiftUI-Introspect", from: "0.1.4")
  ],
  targets: [
    .target(
      name: "BetterTextFieldStyle",
      dependencies: [
        .product(name: "Introspect", package: "swiftui-introspect")
      ],
      path: ".",
      exclude: ["Package.swift"]
    )
  ]
)