[ios] lock button detection timing issue

[yenoss]

Description of the issue

Lock button plugin can't detect immediately.
It's detecting when the app returns from background to foreground.

Users who use the plugin will expect Immediate detection. (like a home button action)

Do you plan to provide this feature in the future?

If you don't support it, I think you should write the README about this timing issue.

Thanks.

[songyiYu]

There is no issue on iphone6 (ios12)

[giantsol]

Thanks.
Closing it cause there seems to be no issue :3