The Android app (available in Google Play) has been around for some time and the iPhone app is unfortunately a poor cousin in terms of functionality due to the limitations of Apple's restrictions in iOS.
The iPhone app is more of a WiFi locator app, though it does have access to Opensignal's coverage data as a map overlay. This is pulled from Opensignal rather than being able to read any information (apart from signal strength and connected network) from iOS itself.
In order to better coverage data, users will still have to download the Android app and use that to map WiFi and cellular signals which are directly exposed in the underlying operating system.
Opensignal could release a Blackberry app as much of the underlying network is also exposed, though whether they will do this is as yet unknown.