Hi!, all... which is the difference between GlobalScope.async and CoroutineScope(context).launch?? can someone explain me

There are 4 differences here.

I need the difference between this

GlobalScope

vs

CoroutineScope(context)

The latter adds an extra allocation. Behaviour is about the same.

ok, I need to access to the contacts of the cellphone, I need this operation async, if I try using CoroutineScope(context) my app blocks, if I try with GlobalScope.launch I get what I want. but Im worjing in kotlin multiplatform so I need this working for android and ios... in android always take the main context by default, but in ios I need to specify it. so I don't know if GlobalScope.launch is gonna work for ios

For `GlobalScope`: It has an ‘empty’ context, ie. no fixed dispatcher (launches, asyncs use the Dispatchers.Unconfined, unless you switch it by using

withContext

, etc), and it has no

Job

(ie. You can’t cancel a

GlobalScope

, for example)

because I never specify a context for ios

When doing

val scope = CoroutineScope()

, it will add a

Job()

to its coroutineContext, by default

Which won't matter if you don't keep a reference to it.

Yup, true. But you may want to provide a

SupervisorJob()

if needed. But the default providing of

Job()

is a good default. But using the factory method

CoroutineScope(...)

, it always will have a Job, which means it is cancelable, whereas GlobalScope isn’t

so I should use a val scope = CoroutineScope(context)

If you are planning on calling

scope.cancel()

at some point, yes.

and if I dont want a scope.cancel()

Looks like it. Be sure to provide the proper dispatcher to your launches and asyncs, since GlobalScope uses the Unconfined dispatcher, which may surprise you here and there 🙂

how I provide a dispatcher in

GlobalScope

?

GlobalScope.launch(dispatcher) { … }

thank you very much! you both are the best ❤️

I must admit, to avoid providing the dispatcher when calling launch and such, instead of GlobalScope, I use CoroutineScope(dispatcher) …. I just never call ‘cancel()’ on it 🙂

why CoroutineScope(dispatcher) blocks me the app and GlobalScope no?

Not sure what you mean with ‘blocks me the app’.

is like CoroutineScope(dispatcher) no has a async behaviour

You said you use it on iOS?

Oh that's why.

@basher just gave a great talk on using coroutines in K/N to do background work – not sure if the slides are up anywhere

Slides are up! No video yet: https://twitter.com/benasher44/status/1166892473303494657?s=21