---
title: Debugging an App Playground using the Console
framework: Swift Playgrounds
role: article
role_heading: Article
path: swift-playgrounds/console-print-debugging
---

# Debugging an App Playground using the Console

Learn different methods to debug your code using console output.

## Overview

Overview When writing code in Swift Playgrounds, you can debug your playgrounds by using print statements and viewing their output in the console. You can filter statements in the console to find specific outputs. Add a print statement Call print(_:separator:terminator) in the code you’d like to debug and add any items you’d like to output to the console. These items output as String values, the same as the output obtained by calling String(item). To customize your debug output for any type, you can add CustomDebugStringConvertible conformance to provide your own implementation for debugDescription. This allows you to print custom String representations for any type and view them in the console. If you’re trying to debug a SwiftUI view, you need to adjust your approach. Because SwiftUI is a declarative framework, you can’t add an imperative print call inside your view declaration. This is because the view body property expects to return a View value. To resolve this, you can use one of several approaches. One approaach to debug your declarative code is to attach the onAppear(perform:) modifier to a view in your body, and call print when the view first appears: Image(systemName: "globe")     .onAppear {         print("This is the debug output.")     } You could also add an extension on View that returns itself and calls the print method: extension View {     func printOutput(_ value: Any) -> Self {         print(value)         return self     } } You can then use printOutput as a view modifier to print debug information to the console when the view is built: VStack {    ForEach(colors, id: \.self) { color in       Circle()          .foregroundColor(color)          .printOutput(color)    } } Understand when and why your views change Another approach that’s particularly useful when debugging SwiftUI view updates is to call the internal method Self._printChanges() from the body of the view — instead of calling print. This records which property caused the view to update and sends that information to the console. In addition to providing property names, @self marks the change to the view value, and @identity marks the change to the view’s identity. var body: some View {     let _ = Self._printChanges()     // View code  } See your app’s output in the Console Press the console button in the code editor to show and hide the console. To adjust the size of the console, you can drag to increase or decrease the available space.

To filter results, tap the filter button and enter a phrase you’d like to filter on. The remaining results filter based upon this input. You can tap to select a result, which allows you to select it as text or to clear the console output by deleting the text.

## See Also

### App playgrounds

- [Adding a Swift package to your app playground](swift-playgrounds/add-a-swift-package.md)
- [Previewing SwiftUI views in Swift Playgrounds](swift-playgrounds/live-preview.md)
- [Requesting access to capabilities for your app playground](swift-playgrounds/project-capabilities.md)
- [Importing sample content into user app playgrounds](swift-playgrounds/using-content-in-user-projects.md)