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Sharing class between iOS app and extension app

I want to use a custom class in both my app and the extension app. If I just have the class in the main app folder, the extension doesn't pick up on it. I tried making a copy of it and putting it into the extension folder, but I of course get a invalid redeclaration of [my class] error. What's the best solution for this? It's just one class, not multiple resources.

Mohamed Elkassas
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Ruben Martinez Jr.
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4 Answers4

57

Nothing should be copied. Just add required files to compile sources for your extension:

enter image description here

Avt
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    Thank you! This looks great! How does this compare to creating a Framework? – Ruben Martinez Jr. Mar 01 '15 at 18:40
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    @RubenMartinezJr. Creating a framework will not build your class for each target separately. but will do it once and link to each target. – Filip Radelic Mar 01 '15 at 18:41
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    @RubenMartinezJr. In no way. You will just share the code between app and extension. They will be compiled separately. So for example you can use #ifdef SOME_EXTENSION_FLAG ... #endif to disable some parts of code during compilation for App or for extension. – Avt Mar 01 '15 at 18:45
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    The downside between this solution and a framework is that effectively the compiled class will be in both the `app` and the `appex` extension, thus increasing the overall size of the IPA file since there is duplication. With a dynamic framework you won't be able to support iOS7 but if you are building a product against iOS8 only, it is a better approach since both the app and the extension will communicate with the same framework. – Edgar Apr 10 '15 at 08:30
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    It seems to be that if I include ClassA.m in Compile Sources and ClassA has dependencies to ClassB and ClassC, I need to include ClassB.m and ClassC.m as well. This can go pretty crazy, if ClassB and ClassC in return has dependencies and so on. Anyone who has a solution to this problem or who can tell me if I'm missing something? Thanks! – Viktor Nilsson Jul 21 '15 at 13:12
  • Don't forget to create a separate Pre-Compile Header file for the extension if you use one in your app. – carloshwa Oct 25 '15 at 08:41
  • Thank You for explainations. Really Helpful :) – Suresh Dec 04 '15 at 19:34
30

Just make sure that the files you want to share gets a tick in the section Target Membership.

Select your file, open the utility panel on the right and tick the appropriate target under Target Membership.

enter image description here

Duc
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6

Embedded frameworks are a great way to reuse code between your application and your extension. Having moved some of the code to embedded frameworks will provide us with a great opportunity to write some unit tests around it.

See section Using an Embedded Framework to Share Code https://developer.apple.com/library/ios/documentation/General/Conceptual/ExtensibilityPG/ExtensionScenarios.html#//apple_ref/doc/uid/TP40014214-CH21-SW1

Praveen Matanam
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3

App Extension(Widget, Today)

App Extension - from iOS v8 - is a packaged bundle which uses different process than Containing App and can communicate with Host App. It has .appex file extension and is located in PlugIns folder. Something similar to CXTests[About]

Application packaged bundle

SpeedWidgetExtension.appex - Application Extension packaged bundle

  • Share data - use App Group[About]
  • Share code

    • Target Membership - the simplest way or for pre iOS v8 which allows you to add files into every target. It increases a footprint of package because this file will be duplicated for every target

    • Framework - module for grouping/reusing code

      • Embedded framework aka Dynamic framework - the most appropriate way to share common code base. Please note that for using Embedded framework you should embed it only in Containing App (and don't add this framework in App Extension. If you include framework and for App Extension it will have the same framework in App Extension bundle - framework will be duplicated). It is possible because of @prath[About]
      //App Extension
LD_RUNPATH_SEARCH_PATHS = @executable_path/../../Frameworks
//It means that App Extension can uses Dynamic framework from Containing app
      • Static Framework - link the code to executable binary. You can link library only for Containing App

[iOS extensions]
[iOS App Group]
[Vocabulary]

yoAlex5
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