DebugModifier.md

DebugView Modifier

Extends View's protocol including some additional modifiers to help debugging SwiftUI

Example

import SwiftUI

struct ContentView: View {
  @State private var count: Int = 0
  var body: some View {
    VStack {
      HStack {
        Text("Hello World")
        Spacer()
        Button { count += 1 } label: { 
          Text("Action")
          .debugBackground()
        }
      }
      .padding()
      .debugBorder()
    }
    .debugPrint("[ContentView]: count = \(count)")
  }
}

See also

• Building SwiftUI debugging utilities

License

MIT

DebugModifier.swift

/*
  DebugModifier.swift
  
  MIT License
  Copyright (c) 2021 Jan Cassio

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.

*/

import Foundation
import SwiftUI

extension View {
  
  /// Perform modifications during rendering.
  /// It works only when the environment flag `DEBUG` is enabled, otherwise, any modification will be made.
  /// - Parameter modifier: Modifiers to be performed during the rendering phase.
  /// - Returns: The current view.
  func debugUsing<T: View>(_ modifier: (Self) -> T) -> some View {
#if DEBUG
    return modifier(self)
#else
    return self
#endif
  }
  
  /// Performs an action during rendering.
  /// Works only when the environment flag `DEBUG` is enabled, otherwise, any closure will be called.
  /// - Parameter closure: A closure to be performed during view rendering phase.
  /// - Returns: The current view.
  func debugPerforming(_ closure: () -> Void) -> some View {
#if DEBUG
    closure()
#endif
    return self
  }
  
  /// Prints a console message during View's rendering phase.
  /// - Parameter item: Any printable value.
  /// - Returns: The current view.
  func debugPrint(_ item: Any...) -> some View {
    debugPerforming {
      print(item)
    }
  }
  
  /// Draws a border around the current view.
  ///
  /// It helps to check the boundaries of some view by drawing a border around it.
  ///
  /// - Parameters:
  ///   - color: The boder's color, default is `Color.red`.
  ///   - width: The border's stroke size, default is `1.0`.
  /// - Returns: A modified view with a border drawend around its boundaries.
  func debugBorder(color: Color = .red, width: CGFloat = 1.0) -> some View {
    debugUsing { $0.border(color, width: width) }
  }
  
  /// Draws a solid color view at background.
  ///
  /// It allows to see the how much space a view takes from the available space provided by the parent's view.
  ///
  /// - Parameter color: The background's view, default is `Color.red`.
  /// - Returns: A modified view with a background that fills the area used by the view.
  func debugBackground(_ color: Color = .red.opacity(0.45)) -> some View {
    debugUsing { $0.background(color) }
  }
}