Hi all I have a conceptual question I want to provide a HTTP

Question

Hi all I have a conceptual question I want to provide a HTTP REST API Wrapper as MPP library As far as I investigated `ktor` it does not manage async execution for me the requests API is `suspend` based So I think I have two options A Manage async execution by coroutines inside the common MPP code From what I recall trying similar things a year ago there are headaches configuring coroutine contexts for iOS and also some limitations main thread only So I am not sure if it all will work at all B Or I can put async logic into platform code More code but ok But still will I be able to call `suspend` marked methods from iOS I d like to have thoughts on this topic from more experienced folks

Tijl · Answer

not sure what you mean by ktor does not manage asynch execution that s exactly what it does in an implementation specific way

Andy Victors · Answer

From what I read in documentation get and request methods are all marked as `suspend` so I cannot use them for async calls without wrapping in coroutines or whatever

Tijl · Answer

from the ktor homepage gt Asynchronous gt Scales as you need it Using Kotlin <https kotlinlang org docs reference coroutines overview html|coroutines> Ktor is truly asynchronous and highly scalable Use the power of non blocking development without the callback nightmare am I understanding you right that you want to do something asynchronously but without wrapping in coroutines or whatever

Tijl · Answer

or do you not mind using it but you want the consumers of your API not to have to deal with it

Andy Victors · Answer

Exactly I do not want customers of my API to take care about any threading etc they just need to call a method which will eventually bring result by calling a callback passed as parameter

Tijl · Answer

by using `suspend` method they will not to worry about those things but if you don t want them to have to call a `suspend`ed method you can do that for them for example you can use <https kotlin github io kotlinx coroutines kotlinx coroutines core kotlinx coroutines deferred |Deffered> and wrap the calls your method do to it in `runBlocking`

Andy Victors · Answer

I cam concerned the most about iOS platform where suspend is not available

Tijl · Answer

suspend is available on iOS

Kris Wong · Answer

kotlin native transforms suspend APIs in the bridging layer to receive a callback instead

Kris Wong · Answer

however the only way to get rid of the suspend on your own APIs is to use `runBlocking`

Kris Wong · Answer

or create your own coroutine scope

Kris Wong · Answer

that said it doesn t need to be removed

Michal Klimczak · Answer

Im working on a solution which exposes coroutines to be easily consumable as callbacks or Swift Combine or RxSwift You can find it here <https github com FutureMind kmm ios suspendwrapper|https github com FutureMind kmm ios suspendwrapper> aeound the middle of the next week I should be able to finish an article on that topic

Andy Victors · Answer

runBlocking will not solve my problem unfortunately because I want to have an async non blocking call Also I assume runBlocking or any similar call needs Coroutine Scope and here we run into trouble on iOS I do not believe there is an official configuration for this so anything I will do will be a tinkerer solution second what is a plain fact even if you manage to use coroutines on iOS they only run in Main Thread I do not want all my network operations to run on network thread this is weird

Michal Klimczak · Answer

Scope can be used in swift code and hidden as implementation detail if you don t want to expose it too much And with coroutines native mt you get background thread as well network calls are no longer run on main thread

Kris Wong · Answer

the latest Ktor requires the coroutines native mt artifact

Kris Wong · Answer

even before that it didn t make requests on the main thread

Michal Klimczak · Answer

Oh didn t know that Does it have its own thread pool or does it use the native mt Dispatchers Default

Andy Victors · Answer

Andy Victors · Answer

I still cannot find any official documentation whether it will work for iOS target

Michal Klimczak · Answer

You are linking a 2y old article We are talking cutting edge technology with new stuff coming out every week Afair coroutines native mt came out officially just a few months ago And it works on ios kotlin native but there are some issues so ymmv

Tijl · Answer

iOS supports coroutines including background ones but as I already pointed out in my first comment ktor handles the async execution per implementation AFAIK it does not use coroutines to switch execution to the background in iOS implementation

Tijl · Answer

coroutines are just the callback mechanism so you can do your ktor request from any dispatcher main default or some runblocking somewhere and ktor will give you the result in that context it does not actually execute there of course this does not change that if you want to consume an API from Swift without using the coroutine bridge there you need to implement your own callback mechanism or use in existing library that provides something like this and call a suspended method from there If you use some thread based solution for this runBlocking should not be a problem obviously Or you can make some solution based around coroutines that you don t expose I would not resolve to googling for articles first since this is a new tool that is quickly evolving Official docs here hopefully answer some of your questions <https kotlinlang org docs mobile concurrency and coroutines html>