How to detect if code is running in Main App or App Extension Target?
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21-12-2019 - |
Question
Does anyone know how you detect from within your code if you're running inside an App Extension?
I have an app which shares classes between an app and an extension. The app code uses [UIApplication sharedApplication]
but this isn't available from within an extension, so it won't compile saying:
'sharedApplication' is unavailable: not available iOS (App Extension)
So I need a way to detect that I'm in the extension and use an alternative to sharedApplication
if that's the case.
Solution
You can use a preprocessor macro:
In the project settings use the dropdown in the topbar to select your extension target:
Then:
- Click
Build Settings
- Find (or search)
Preprocessor Macros
underApple LLVM 6.0 - Preprocessing
- Add
TARGET_IS_EXTENSION
or any other name of your choice in both the debug and release sections.
Then in your code:
#ifndef TARGET_IS_EXTENSION // if it's not defined
// Do your calls to UIApplication
#endif
OTHER TIPS
As Apple's documentation says:
When you build an extension based on an Xcode template, you get an extension bundle that ends in .appex.
So, we can use the following code:
if ([[[NSBundle mainBundle] bundlePath] hasSuffix:@".appex"]) {
// this is an app extension
}
The preprocessor macro will work mostly, but will not work in shared library (e.g. cocoapods or shared frameworks).
Alternatively you can use following code.
@implementation ExtensionHelpers
+(BOOL) isAppExtension
{
return [[[NSBundle mainBundle] executablePath] containsString:@".appex/"];
}
@end
This work by checking the bundle executablePath, as only App Extension has extension ".appex".
You can add a preprocessor macro on the extension target and then check with a #ifdef
inside of your class.
Swift 5
let bundleUrl: URL = Bundle.main.bundleURL
let bundlePathExtension: String = bundleUrl.pathExtension
let isAppex: Bool = bundlePathExtension == "appex"
// `true` when invoked inside the `Extension process`
// `false` when invoked inside the `Main process`
For my shared library I created a separate target who's app extensions flag is set to yes, and used preprocessor macro's within the build settings for that specific target.