feat: support async crop

[guoyingtao]

fix #161

[vanniktech]

Would be nice to also have an API where activityIndicator isn't used at all. I'd want to have my own loading view shown instead of the one from the library

[guoyingtao]

Would be nice to also have an API where activityIndicator isn't used at all. I'd want to have my own loading view shown instead of the one from the library

Thanks for the suggestion! I will think about it.

[vanniktech]

Do we also need?

Suggested change

	DispatchQueue.global(qos: .userInteractive).async {
	DispatchQueue.global(qos: .userInteractive).async { [weak self] in

[guoyingtao]

No it is not needed. DispatchQueue does not hold strong self to it won't cause retain cycle.
You can test it by putting a breakpoint in deinit

[guoyingtao]

I found some code in crop() which should only be called in the main thread. I need to fix them.

[guoyingtao]

I found some code in crop() which should only be called in the main thread. I need to fix them.

Fixed

[guoyingtao]

Would be nice to also have an API where activityIndicator isn't used at all. I'd want to have my own loading view shown instead of the one from the library

I created a new issue #233 and plan to do it in a separate PR.