AppAvailability Bug
appAvailability.check returns alway error callback.

iOS 9 Error in Xcode
-canOpenURL: failed for URL: "<scheme>://" - error: "This app is not allowed to query for scheme <scheme>"

Explanation
Apple changed the canOpenURL method on iOS 9. Apps which are checking for URL Schemes have to declare these Schemes as it is submitted to Apple. The article 

Solution: Add URL Schemes to the Whitelist
Simply open your app's .plist (usually platforms/ios/<appname>/<appname>-Info.plist) with an editor and add the following code with your needed Schemes.

<key>LSApplicationQueriesSchemes</key
 
>
<array>
    <string>twitter</string>
    <string>whatsapp</string>
</array>