fix(ios): getSSID and getBSSID always returning null

[DominikStarke]

This patch adresses issues
#161
and
#105

It adds a callback function to getSSID, which will resolve the result.
This is since NEHotspotNetwork.fetchCurrent's completionHandler is escaping. As a result ssid will never be set.

[daadu]

I do not know iOS much.

Requesting @Niek @diegotori, can you review the fix?

[daadu]

Did some basic google searches, looks like since we are setting ssid inside getSSID inside a closure (namely completionHandler) which by-default are nonescaping (since Swift 3) it not being set because it is "out of scope" of the outer function.

These fix adds a callback to getSSID as param, which is called when the "SSID" is fetched.

@DominikStarke correct me if my understanding is wrong.

Resources:

• https://medium.com/swiftcommmunity/what-do-mean-escaping-and-nonescaping-closures-in-swift-d404d721f39d

This fix LGTM, waiting for others to review.

[diegotori]

@daadu LGTM as well, since it's now handling the iOS result much better.

[DominikStarke]

Yes. The current implementation is running out of scope. getSSID returns before fetchCurrent's handler is executed.

[DominikStarke]

I added another commit to apply this fix to getBSSID.

[daadu]

Thanks @DominikStarke for the fix.

This has landed on pub.dev with v0.3.7