I d like to create some interfaces in the common shared code

Question

I d like to create some interfaces in the common shared code that will be implemented in platform specifics code Android iOS either via expect actual but more likely interfaces implemented in separate packages What would be the best way to pass in Platform specific objects for example Context Activity in Android and equivalents in iOS I d imagine this could be a quite common scenario didn t find an example on the Kamp Kit app unless I ve missed it

russhwolf · Answer

It s much easier to do this with interfaces than expect actual KaMPKit has a couple examples of this Some are in libraries eg `SqlDriver` and `Settings` and there s a dummy `AppInfo` class to demonstrate more explicitly That one doesn t pass a context on the Android side but it easily could

russhwolf · Answer

KaMPKit is passing all of that into Koin but the same patterns should translate to any other dependency management API you might use

Alberto · Answer

Thanks a lot for the pointer will take a look

Alberto · Answer

Took a look at those examples it seems they are mostly dealing with primitive types but was wondering what would be a good design for platform specific classes For example adding a getPlatformContext to the AppInfo that returns an Android Context on Android and something else for iOS I guess it could be achieved using generic objects or Any with casts

russhwolf · Answer

The details are going to depend a lot on your use case But in general you re more often going the other way where an Android thing needs a `Context` input that iOS doesn t And in that case having separate per platform implementations or even just separate constructors or factory methods is usually enough

russhwolf · Answer

It s rare that I find myself looking for a `Context` from common code because I ve usually already given it to the things that need it at construction time

Alberto · Answer

that makes sense passing it in construction time I guess an example would be having a method to show hide a dialog in the common code which would be implemented in Android and iOS platform code Usually to show UX stuff we have to pass in Context objects on Android so was considering putting it in the method itself but perhaps could try to move it at creation time as you pointed out

russhwolf · Answer

Yeah It might get dicier there if you need an activity context instead of application But it should still be possible to get working As long as the platforms are responsible for initializing platform specific code you can pass platform specific dependencies

Alberto · Answer

on a related note have you put any thoughts on how to use some observables specific platform implementation from the common code Like for example having a method in a common interface that returns an observable On Android the observable could be LiveData or using RX while on iOS something else

russhwolf · Answer

That again is going to depend a lot on use case I wrote about coroutine and RxSwift interop here for one example but there s lots of other ways you could do things instead <https dev to touchlab working with kotlin coroutines and rxswift 24fa>

Alberto · Answer

will go through that appreciate sharing that and writing it