Hey folks - kicking off a project at work, in which we need to build native SDKs. Thinking about usi...

# multiplatform

[Jagtej Sodhi]

Hey folks - kicking off a project at work, in which we need to build native SDKs. Thinking about using KMP for shared logic, and then depending on the KMP portion in the native SDKs, which will have platform specific logic*.* There's plenty of tutorials out there for building KMP apps, but not many for SDKs.

Has anyone done this and can share overall experience?

[brandonmcansh]

working on this right now actually

[brandonmcansh]

using shared compose UI as well

[Jagtej Sodhi]

Ah nice! have so many questions for you - first, how did you structure the code?

KMP logic in it's own standalone repo, or a mega repo w/ Android + iOS + KMP code?

[Jagtej Sodhi]

Second - Do your native SDKs depend directly on the source code of your KMP project, or do you build binaries and depend on those?

[brandonmcansh]

repo is SDK plus sample apps

[brandonmcansh]

sample iOS app depends on cocoapod (from a local path for development); sample android uses the local source

[brandonmcansh]

for iOS I ./gradlew sdkpodPublishDebugXCFramework and build it with xcode after

[Jagtej Sodhi]

was just going to ask that. okay so KMP publishes local framework to cocoapod, then you consume that in the ios sample app

[brandonmcansh]

yep

[brandonmcansh]

Podfile for sample app is

[Jagtej Sodhi]

Do you have a native SDK layer between the sample app and KMP library?

[brandonmcansh]

target 'sample-ios' do
  # Comment the next line if you don't want to use dynamic frameworks
  use_frameworks!
  platform :ios, '15.0'

  if ENV.include?("LOCAL_KOTLIN_PATH")
     pod 'BotStacksSDK', :path => ENV["LOCAL_KOTLIN_PATH"]
  else
    pod 'BotStacksSDK', '0.0.1'
  end
end

[brandonmcansh]

not at the moment

[brandonmcansh]

our "SDK" is a fully encompassing viewcontroller for both platforms

[brandonmcansh]

drop into existing app sort of thing

[brandonmcansh]

navigate to it and it runs

[brandonmcansh]

trying to see if I can bundle swift structs with the SDK to cleanup the footprint for iOS devs but havent had luck ywet

[brandonmcansh]

yt*

[brandonmcansh]

yet**

[brandonmcansh]

e.g to abstract this

struct BotStacksChatController : UIViewControllerRepresentable {
    func makeUIViewController(context: Context) -> UIViewController {
        let vc = BotStacksChatControllerKt.BotStacksChatController(onLogout: {})

        return vc
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: Context) {}
    
}

[Jagtej Sodhi]

Ah got it. My goal is to have a KMP project with has shared logic (networking), and then have two separate native SDKs that depend on the KMP side.

I'll then have two sample apps that depend on the native SDKs (while KMP stays completely internal to the SDKs)

[Jagtej Sodhi]

trying to see if I can bundle swift structs with the SDK to cleanup the footprint for iOS devs but havent had luck ywet

This is exactly why I plan to have the middle layer of native SDKs. iOS Swift SDK will abstract some of the annoying KMP <> objc issues for our iOS devs.

[Jagtej Sodhi]

that + native UI

[brandonmcansh]

nice

[brandonmcansh]

like it

[Jagtej Sodhi]

I built this entire abstraction layer at my old job - wish I open sourced it. Could have been helpful to both of us right now.

[Jagtej Sodhi]

Is your project open source?

[brandonmcansh]

will be soon

[Jagtej Sodhi]

@brandonmcansh would you be down for a 30 min chat? could chat through our SDK setups / bounce ideas off each other. (this week or next?)

[Pablichjenkov]

There is plenty of SDKs too. I have a GitHub list but don't see how to get a shareable link. Below is a good library as an example to consume a service.
https://github.com/MoviebaseApp/tmdb-kotlin

[Jagtej Sodhi]

Nice, will check this out!

[Pablichjenkov]

In regards to embed swift code in klibs, not sure if possible. I tried without success, I ended up using a separate swift package in GitHub which depends on the KMP lib interfaces and it also contains the implementations.
The downside is users need to import both a KMP lib in the iOS umbrella module and a Swift Package in the swiftui App, a bit hacky TBH

[Jagtej Sodhi]

@Pablichjenkov going through your readme. where is the instruction on how to include your SDK in an ios app?

[Pablichjenkov]

Well I am not the author of that library, I just picked it randomly, I think is a pretty good example of an SDK

[Pablichjenkov]

Ah I see, I just realized they don't have examples of how to use it. Sorry about that. But in general you just place the dependency in commonMain and that is it.

[Jagtej Sodhi]

All good - I was referring to the cocoapod / spm integration steps

[Jagtej Sodhi]

but this is still helpful, i'll take a look

[Pablichjenkov]

Ah ok, I really can't help with cocoapods. I haven't used it in a while.

[Jagtej Sodhi]

All good, thanks for the insight!

[brandonmcansh]

Looks like I have to actually support component usage as well @Jagtej Sodhi. Abstraction layer for iOS it is

[Jagtej Sodhi]

Nice! I think that'll be cleaner longer term (esp so you can abstract kotlin <> objc translation that doesn't work well with swift).

[brandonmcansh]

Yep yep

[Jagtej Sodhi]

Your iOS abstraction layer will also be an SDK?

[Jagtej Sodhi]

or building that logic directly into the app?

[brandonmcansh]

SDK

[Jagtej Sodhi]

have you thought through that yet? swift package? framework?

[brandonmcansh]

hoping for a swift package

[Jagtej Sodhi]

And you'll compile the KMP framework and add it as a dependency in your swift package?

[Jagtej Sodhi]

^^ this is what I did in my old app. Had a build phase step that generated the framework, and then my ios app referenced the framework. That way, any time i made changes to the KMP source, I could test directly against it.

[Jagtej Sodhi]

But with Swift package, it's not as straight forward

[brandonmcansh]

And you'll compile the KMP framework and add it as a dependency in your swift package?

was my plan 🙂

[Jagtej Sodhi]

How do you plan to compile against the KMP sources? Ideally I want to setup a dev environment where I can make changes to KMP source that immediately get reflected in the iOS SDK (without having to manually regenerate the framework each time).

I guess I could write a script that does it automatically, but wondering if there's an easier way (like the build phase process I described above). Note: swift packages don't have build phase steps.

[brandonmcansh]

still up in the working

[brandonmcansh]

working on the component stability in my sample-app sandbox first and then tackling rebundling/abstraction

[brandonmcansh]

existing API layer I inherited is an eyesore

[Jagtej Sodhi]

oof

[Jagtej Sodhi]

no worries, loop me in when you get to it

[Jagtej Sodhi]

i can let you know how my setup pans out

[brandonmcansh]

any updates by chance? Have to pivot to this to hopefully get these released in a beta fashion next week 👀

[Jagtej Sodhi]

Somewhat, stuck on one thing. Want to jump on a huddle today? Can walk you through what I have.

[brandonmcansh]

yep whats your day look like