How to import own classes from your own project into a Playground

Assume a setup like this:

  • You have an Xcode 6 project, where you've implemented your own classes (say MyView and MyViewController) with both Objective-C and Swift
  • You have added a Playground into your project

In the Playground, it's possible to import modules (frameworks) like UIKit with the import keyword. How do you enable access to the project's other classes from the Playground?

Just trying to access project classes directly results with an error message: Use of unresolved identifier 'MyView'

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最佳答案

As of Xcode 6.0 Beta 5, it is now possible to import your own frameworks into a playground. This provides a way to share code between your applications and playgrounds, which can both import your frameworks. To do this:

  1. Your playground must be in the same workspace as the project that produces your framework. Your workspace must contain a target that produces the framework, instead of using a pre-built framework.

  2. You must have already built your framework. If it is an iOS framework, it must be built for a 64-bit run destination (e.g. iPhone 5s), and must be built for the Simulator.

  3. You must have an active scheme which builds at least one target (that target's build location will be used in the framework search path for the playground).

  4. Your "Build Location" preference (in advanced "Locations" settings of Xcode) should not be set to "Legacy".

  5. If your framework is not a Swift framework the "Defines Module" build setting must be set to "Yes".

  6. You must add an import statement to your playground for the framework.

Once all these conditions are fulfilled, importing your framework will work in a playground.

In Xcode 7 we introduced another mechanism that you can use to import your own classes as source, instead of importing a framework; you can read about this "Auxiliary Sources" support at http://help.apple.com/xcode/mac/8.0/#/devfa5bea3af

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I actually managed to refer to other Swift files in the current project by doing this:

  • Create an empty Playground and place is somewhere under your project.
  • Open the YourPlayground.playground bundle (yes, it's a bundle = directory) in Terminal.
  • Edit contents.xcplayground for example with vi and add another section like this:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<playground version='3.0' sdk='iphonesimulator'>
<sections>
<code source-file-name='section-1.swift'/>
<code source-file-name='section-2.swift'/>
</sections>
<timeline fileName='timeline.xctimeline'/>
</playground>
  • Rename section-1.swift to section-2.swift (if you created the Playground from scratch, there should be an example section-1.swift in your bundle)
  • Add a hard link (symbolic link doesn't seem to work) named section-1.swift which will point outside the bundle to your Swift class file like:
ln ../../Classes/MyView.swift section-1.swift
  • Close Xcode and open the Playground again.
  • Now there should be two sections, one with the contents of your Swift class file and the other one with the example content you got from creating the Playground from scratch.

This way I can actually run code lying outside the Playground, but Xcode seems to crash more often when doing it like this.

Edit:

As of Xcode 6 beta 5 you're now able to refer to project files, as Rick Ballard instructs in his answer.

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Since Beta 5 of Xcode 6 it is possible to import your code if it is in a framework. What you need to do is create a framework target, add the Swift files there and in your playground do

import ModuleName

You can look up the module name in the build settings. It's usually the same as the target name.

Remember to make the code you want to see public. You'll need to build the project before changes are available in the playground. (You'll also need to edit the playground to trigger re-execution.)

Important

Do not give the playground file the same name as the target! If you do, importing seems to work but you'll get the following error when the playground tries to execute:

Playground execution failed: error: Couldn't lookup symbols:

I wasted an hour on figuring that out. :)

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All you have to do - is write in the beginning:

import ModuleName

(assuming your playground placed in the same workspace as framework/project)

If it's doesn't work:

  1. Rebuild your project

  2. Recreate playground and copy all from old playground there

It solves a lot of strange errors with failed init's and imports of whatever!

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I wasn't able to get it working using any of the answers here, so I started playing around and found a simple way that worked for me to import a swift class into a playground.

Just create a playground in your project, theres a directory inside it called 'sources', just drag a copy of the swift class into that folder and the playground then will have access to it.

For example:

enter image description here

小开

I just put links to all my swift files in the Sources folder:

cd /path/to/project/MyPlayground.playground/Sources
ln -s ../../*.swift .

This way changes in your source file will take effect in your playground immediately. Worked very nicely.

Xcode 8.2, Swift 3.0.1, macOS Sierra


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