libCanOpenURL

iOS 11+

applicationsAvailableForHandlingURLScheme api is restricted. I don't know how to bypass this restriction, libCanOpenURL come back as robust way for it.

iOS 9-10

This is deprecated library to get handleable url scheme.
More easist and no self IPC way is -[LSApplicationWorkspace applicationsAvailableForHandlingURLScheme:] method. (Detail #3)

detail

This is sample project to use LightMessaging.

After iOS 9, canOpenURL: method always returns NO if not declared on application Info.plist. libCanOpenURL calls canOpenURL: via SpringBoard process to bypass this restriction.

Weak library link.

If your tweak supports iOS 8 and earlier, a weak library link is useful.

XXX_LDFLAGS += -weak_library $(THEOS)/lib/libcanopenurl.dylib

Acknowledgment

All of the implementation design copied from AppList by rpetrich.