iOS File Association in Xamarin Forms application?

Hello guys,
hopeyfully this is the correct forum for my request.

I am working on a Xamarin Forms application. Now I want to implement File Association for the iOS App for PDF and png files.
Therefore I added this to the plist file.

<key>CFBundleDocumentTypes</key>
        <array>
            <dict>
                <key>CFBundleTypeName</key>
                <string>PDF</string>
                <key>LSHandlerRank</key>
                <string>Alternate</string>
                <key>LSItemContentTypes</key>
                <array>
                    <string>com.adobe.pdf</string>
                </array>
            </dict>
            <dict>
                <key>CFBundleTypeName</key>
                <string>PNG</string>
                <key>LSHandlerRank</key>
                <string>Alternate</string>
                <key>LSItemContentTypes</key>
                <array>
                    <string>public.png</string>
                </array>
            </dict>
        </array>

In the appdelegate I catch the file like this:

public override bool OpenUrl(UIApplication application, NSUrl url, string sourceApplication, NSObject annotation)
 {       
     Console.WriteLine("Invoked with OpenUrl: {0}", url.AbsoluteString);
     return true;
 }

Based on this I wan't the app to navigate to a page were I am willing to use the file.

Now I ran into a problem. When I import a file to the app nothing happens and I get the following error in the devicelog:

Sep 14 11:42:09 stefans-imac2.andagon.local com.apple.mdt[6159]: Copy /Users/pasqueju/Library/Developer/CoreSimulator/Devices/8AEFCE3E-EEA8-475F-9E3F-174B8E9AD8EB/data/Containers/Data/Application/E354FC7C-744E-41E6-9B13-9A66BE0E7AEC/tmp/QuickLookPDF-peBjnPAz/entgeltbeleg_muster.pdf -> /Users/pasqueju/Library/Developer/CoreSimulator/Devices/8AEFCE3E-EEA8-475F-9E3F-174B8E9AD8EB/data/Containers/Data/Application/01A2661A-FFEE-4A6D-AF49-559484162433/Documents/Inbox
Sep 14 11:42:09 stefans-imac2 assertiond[4323]: assertion failed: 14F27 12F69: assertiond + 12334 [8E465C14-E4AE-36E9-AFBE-D28459602962]: 0x1
Sep 14 11:42:09 --- last message repeated 6 times ---
Sep 14 11:42:09 stefans-imac2.andagon.local AndagonAppiOS[6150]: Invoked with OpenUrl: file:///Users/pasqueju/Library/Developer/CoreSimulator/Devices/8AEFCE3E-EEA8-475F-9E3F-174B8E9AD8EB/data/Containers/Data/Application/01A2661A-FFEE-4A6D-AF49-559484162433/Documents/Inbox/entgeltbeleg_muster.pdf
Sep 14 11:42:09 stefans-imac2.andagon.local SpringBoard[4319]: [MPUSystemMediaControls] Updating supported commands for now playing application.
Sep 14 11:42:09 stefans-imac2.andagon.local splashboardd[6160]: *** Assertion failure in -[UINib initWithNibName:directory:bundle:], /SourceCache/UIKit_Sim/UIKit-3347.44/UINib.m:98
Sep 14 11:42:09 stefans-imac2.andagon.local splashboardd[6160]: *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid parameter not satisfying: (name != nil) && ([name length] > 0)'
    *** First throw call stack:
    (
        0   CoreFoundation                      0x000000010405dc65 __exceptionPreprocess + 165
        1   libobjc.A.dylib                     0x0000000103cbabb7 objc_exception_throw + 45
        2   CoreFoundation                      0x000000010405daca +[NSException raise:format:arguments:] + 106
        3   Foundation                          0x000000010382698f -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 195
        4   UIKit                               0x00000001027762a0 -[UINib initWithNibName:directory:bundle:] + 164
        5   UIKit                               0x000000010277639d +[UINib nibWithNibName:bundle:] + 61
        6   splashboardd                        0x0000000101d29847 splashboardd + 6215
        7   libdispatch.dylib                   0x0000000104973964 _dispatch_client_callout + 8
        8   libdispatch.dylib                   0x0000000104960818 _dispatch_barrier_sync_f_slow_invoke + 51
        9   libdispatch.dylib                   0x0000000104973964 _dispatch_client_callout + 8
        10  libdispatch.dylib                   0x000000010495ea59 _dispatch_main_queue_callback_4CF + 704
        11  CoreFoundation                      0x0000000103fc51f9 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
        12  CoreFoundation                      0x0000000103f86dcb __CFRunLoopRun + 2043
        13  CoreFoundation                      0x0000000103f86366 CFRunLoopRunSpecific + 470
        14  Foundation                          0x00000001037c7f92 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 275
        15  Foundation                          0x0000000103853080 -[NSRunLoop(NSRunLoop) run] + 74
        16  splashboardd                        0x0000000101d29d0c splashboardd + 7436
        17  libdyld.dylib                       0x00000001049a3145 start + 1
    )
Sep 14 11:42:09 stefans-imac2.andagon.local SpringBoard[4319]: BSXPCMessage received error for message: Connection interrupted
Sep 14 11:42:09 stefans-imac2 com.apple.CoreSimulator.SimDevice.8AEFCE3E-EEA8-475F-9E3F-174B8E9AD8EB.launchd_sim[4305] (com.apple.splashboard.9411E059-C0CD-4AE5-9034-F1D350BC274C[6160]): Service exited due to signal: Abort trap: 6
Sep 14 11:42:09 stefans-imac2 assertiond[4323]: assertion failed: 14F27 12F69: assertiond + 12334 [8E465C14-E4AE-36E9-AFBE-D28459602962]: 0x1
Sep 14 11:42:39 --- last message repeated 7 times ---

Irrespective of this error I was wondering how to navigate away from the appdelegate anyways.
Did anyone of you already implement file association and solved these problems?

Best regards
Julian