Playground Driven Development example

This example demonstrates how to use your entire xcode project in a playground. You can quickly preview/prototype/build/change things (especially UI).

With this workflow you can have the advantage of storyboards while having the UI in code.

Inspired from Kickstarter's Playgrounds usage.

This example uses Cocoapods for dependency management, but you can use your preferred solution as well, the aproach is similar.

Table of contents:

• Steps to add playground support to your project
• Steps to try the example project out
• Workflows
• Handling dependency issues
• Tips and tricks
• Known issues
• Troubleshooting

Steps to add playground support to your project:

• create a playground in you project

• create a dynamic framework target

• declare it in the Podfile, add all the dependencies that you have on your other target(s)

• pod install

• add your classes to the framework target (View > Utilities > Show File Inspector, under Target Membership check your framework target)

• build the framework target with SIMULATOR

• import framework in playground: @testable import MyProjectFramework

  @testable make internal classes and members open

Steps to try the example project out

• clone the repo
• open playground-driven-development.xcworkspace
• select projectFramework scheme and build it
• select playground from the file navigator
• open Assistant editor
• wait a little
• you should see some colored views, one of them moving

So what did I just see?

• usage of a class in playgrounds that's in your project (without copying it in the playground)
• usage of a pod library (Dance) that's a dependency of your project

Workflows

• new UI:
  • create your UI in playground
  • when you're satisfied with the results, add it to the project
• existing UI needs update. You could modify your project files and build the project framework, but this is much slower. Instead:
  • copy the affected code in the playground (modify the class names to avoid duplicate symbols)
  • when you're satisfied with the results, overwrite the project's code with that of the playgrounds

Handling dependency issues

Tips and tricks

• playground likes to run all the time, even if you stop it, it restarts after a short while. To stop it for real, long click on the play/stop button, and select Manually Run.
• if you want to use custom fonts, you need to do this before:

  // fonts are under Resources/fonts
  var fontUrl = Bundle.main.url(forResource: "MyCustmFontName", withExtension: "ttf", subdirectory: "fonts")
  CTFontManagerRegisterFontsForURL(fontUrl as! CFURL, CTFontManagerScope.process, nil)
  

Known issues

• PDF vector images are not working
• there's no self in the playground's "root", so if you want to implement a target-action or delegate pattern here (not inside a class), create an object that will be the target or the delegate instead of self. You also need to assign it to a local variable, and then use it:

  let chartView = ChartView()
  let delegate = ChartDelegate() // doesn’t work if assigned directly
  chart.delegate = delegate
  

Troubleshooting

Unfortunately playgrounds is still flaky (it's xcode after all), where many times it just doesn't work and you have no idea why.

If the playground doesn’t work

When the panel on the right of the editor doesn't show anything or text is greyed out

• stop it and run it again
• restart xcode (the whole app (cmd-q) not just the windows)
• make sure simulator isn’t open

If live view isn't showing

• try the things from the previous section
• close and reopen assistant editor
• close assistant editor, stop/start playground, open assistant editor
• make sure to set the view’s frame before assigning it to liveView