Linked frameworks and libraries in Swift project

Question

My iOS app plays sounds with AVPlayer. To do this I had to type following on the top of a class:

import AVFoundation

I came from Objective-C background, so I went to Xcode project's General tab and added AVFoundation there by clicking on plus button under the Linked frameworks and libraries. Yellow toolbox appeared in my project. Do I have to do this?

I tried to remove it from the project — both from the sidebar and in Xcode preferences, my app still works and sounds are playing. So does import handling everything for you?

Answer 1

Yes, import in Swift is basically the same as @import in Objective-C (as opposed to #import <…>), which import modules.

This new feature (modules) was introduced recently (1-2 years ago?) and does import the framework for you without the need to explicitly link you app with it: when using modules (@import in ObjC, import in Swift), the compiler will see the module name and link your app with the framework implicitly and automagically for you.

So that's a new feature we didn't have back in the day when #import were the only option and we had to manually add system frameworks ourselves.

(Note that modules were only available for Apple's frameworks until iOS8 arrived. But now that you can build your own dynamic frameworks when building for iOS8, they are available for third-party frameworks as well, as long as they have a module.map)

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If you're interested, you can read more in the Clang documentation itself. Various blog posts also talk about the subject (e.g. first Google result is this blog post)