ios - canOpenURL failing for system-wide URL schemes

Question

I'm running iOS 9b5.

In my app, if a device can make a phone call, I want to color the text blue so it looks tappable. If not, I leave it black.

In order to determine the device capabilities, I use:

[[UIApplcation sharedApplication] canOpenURL:@"telprompt://5555555555"]  

As we all know, iOS 9 requires we whitelist any URL schemes we'll be using in our app as a privacy measure.

I have this in my Info.plist:

<key>LSApplicationQueriesSchemes</key>  
<array>  
  <string>telprompt</string>  
</array>  

No matter what I do, I still get canOpenURL: failed for URL: "telprompt://" - error: "(null)". I've tried tel:// and sms:// and I can't seem to avoid that syslog warning.

Does anybody know of a way to detect whether or not a device can make a phone call wtihout triggering these warnings?

Answer 1

What I discovered so far is, that if the console logs -canOpenURL: failed for URL: "xxx://" - error: "(null)", it actually works. As soon as there is any other error than null, it may not work. If the error is "This app is not allowed to query for scheme xxx", then you have to add this scheme to your app's .plist:

<key>LSApplicationQueriesSchemes</key>
<array>
    <string>xxx</string>
</array>

Strange behavior that the console output looks like an error although there is none, indeed.