Feat/async start and updateContext overloads

[benjamin-es-hall]

About the changes

This adds async overloads for the start and updateContext methods so that they can safely be called from async context in modern swift concurrency. MainActor requirement is needed for the timer within the Poller to fire on the RunLoop.

Fairly sure this should close #88
Closes #88

Important files

Discussion points

[FredrikOseberg]

@benjamin-es-hall Thank you! I think it looks sensible, but how will this affect the minimum version of Unleash? In the past we changed away from the usage of ObservableObject on the base in order to support iOS 12. See #34

[benjamin-es-hall]

@benjamin-es-hall Thank you! I think it looks sensible, but how will this affect the minimum version of Unleash? In the past we changed away from the usage of ObservableObject on the base in order to support iOS 12. See #34

No problem!

Oh I didn't notice UnleashClient was exposed only to iOS13 and that was the differencing factor to UnleashClientBase.

In that case, the async methods I've put in Base I've marked for only available to iOS13 and shouldn't have any issues, but I think we could equally just move them into UnleashClient. Thoughts?

Would you also be able to explain why ObservableObject is used? It's use case is not clear to me without an example since any changes seem to be propagated via the swiftEventBus and notification center anyway?

[benjamin-es-hall]

@FredrikOseberg just pushed up a commit to move the methods to the UnleashClient class where it already specifies iOS13 requirement

[FredrikOseberg]

@benjamin-es-hall Thank you! I think it looks sensible, but how will this affect the minimum version of Unleash? In the past we changed away from the usage of ObservableObject on the base in order to support iOS 12. See #34

No problem!

Oh I didn't notice UnleashClient was exposed only to iOS13 and that was the differencing factor to UnleashClientBase.

In that case, the async methods I've put in Base I've marked for only available to iOS13 and shouldn't have any issues, but I think we could equally just move them into UnleashClient. Thoughts?

Would you also be able to explain why ObservableObject is used? It's use case is not clear to me without an example since any changes seem to be propagated via the swiftEventBus and notification center anyway?

Observable object was initially used to allow UI changes to propagate automatically when a feature flag updated. Without it, from my understanding, you'll have to trigger the UI update manually yourself. This was done to keep consistency with how our other client side SDKs handle flag changes.

[FredrikOseberg]

LGTM