NTKCustomFace

Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.

Jeff Goldblum

This project is a result of a weekend long research into the inner workings of NanoTimeKit framework and Carousel process inspired by @steventroughtonsmith work on his SpriteKitWatchFace project.

It is heavily based on a similar (but outdated) project by @hamzasood.

How Does this work?

By hijacking the _addableFaceCollection property of the NTKFaceLibraryViewController we are able to directly modify the dictionary to also include our custom subclass of the NTKFace.

This adds the custom face to the list of available ones, and then by swizzling the loadView on the NTKFaceViewController we can replace the standard view with our custom one.

This is obviously nowhere close to how the API should be used and further research is needed to fully understand the process.

Setup:

Before you will be able to compile the project you will have to move 2 private frameworks from the watchOS Simulator to the Private Frameworks directory.

Frameworks in questions are: NanoTimeKit and RelevanceEngine, you can find them inside Xcode bundle:

/Applications/Xcode.app/Contents/Developer/Platforms/WatchOS.platform/Developer/Library/CoreSimulator/Profiles/Runtimes/watchOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/

The project also depends on a watchOS Simulator with a name Apple Watch Series 4 - 44mm being present. This is the standard name that Xcode uses, but if you have renamed your simulated devices, you will have to modify the launcher.sh file (look for the SIMULATOR_NAME constant).

Running:

In the ideal world all you should have to do is open Xcode project and hit ⌘+R. This should compile the project, boot up the watchOS Simulator, restart the Carousel process and in the end inject the compiled library using some lldb magic.

Limitations:

• Currently all of the NanoTimeKit and UIKit are forward declared in the NanoTimeKit.h file. This is not the ideal solution, so another way of importing those headers needs to be found.
• Since we're compiling an library, assets like images are not properly supported.
• This obviously doesn't work on actual hardware.

Further research:

• Support for customization through official UI
• Support for complications
• Proper way of injecting the watch faces instead of directly modyfing the presenation model.
• Better way of linking with NanoTimeKit and UIKit so all classes are available for use.