UIActivityViewController Attaching File - Wrong File Type - iphone

Question

I am using UIActivityViewController to share the contents of my app in both a pure text format as well as a custom filetype that can be opened on other devices. The file attaches to the email created with no problem, however it is getting the wrong filetype associated with it. The custom file that is created is an NSDictionary that uses writeToURL.
NSMutableDictionary *theBinder = [NSMutableDictionary dictionaryWithObjects:#[#"test object"] forKeys:#[#"test key"]];
NSURL *binderURL = [NSURL fileURLWithPath:[[self cachesDirectory] stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.mtgbinder", [[NSUserDefaults standardUserDefaults] valueForKey:#"Current Binder"]]]];
[theBinder writeToURL:binderURL atomically:YES];
NSArray *activityItems = [NSArray arrayWithObjects:binderContents, binderURL, nil];
UIActivityViewController *shareView = [[UIActivityViewController alloc] initWithActivityItems:activityItems applicationActivities:nil];
shareView.excludedActivityTypes = #[UIActivityTypePostToTwitter, UIActivityTypePostToWeibo];
[self presentViewController:shareView animated:YES completion:nil];
The file is correctly created as expected:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>test key</key>
<string>test object</string>
</dict>
</plist>
However, when I then try to open that file from another app, the extension gets changed to csv. My app is able to open and export both my mtgbinder filetypes and also CSV. Am I doing something wrong with the UTExportedTypeDeclarations?
<key>UTExportedTypeDeclarations</key>
<array>
<dict>
<key>UTTypeConformsTo</key>
<array>
<string>public.data</string>
</array>
<key>UTTypeIdentifier</key>
<string>com.chichapps.MTG-Binder.csv</string>
<key>UTTypeTagSpecification</key>
<dict>
<key>public.filename-extension</key>
<string>csv</string>
<key>public.mime-type</key>
<string>application/MTG-Binder</string>
</dict>
</dict>
<dict>
<key>UTTypeIdentifier</key>
<string>com.chichapps.MTG-Binder.mtgbinder</string>
<key>UTTypeDescription</key>
<string>MTG Binder Document</string>
<key>UTTypeTagSpecification</key>
<dict>
<key>public.mime-type</key>
<string>application/MTG-Binder</string>
<key>public.filename-extension</key>
<string>mtgbinder</string>
</dict>
<key>UTTypeConformsTo</key>
<array>
<string>public.data</string>
</array>
</dict>
</array>
<key>CFBundleDocumentTypes</key>
<array>
<dict>
<key>CFBundleTypeName</key>
<string>MTG Binder Document</string>
<key>LSHandlerRank</key>
<string>Owner</string>
<key>CFBundleTypeRole</key>
<string>Editor</string>
<key>LSItemContentTypes</key>
<array>
<string>com.chichapps.MTG-Binder.csv</string>
<string>com.chichapps.MTG-Binder.mtgbinder</string>
</array>
</dict>
</array>
Thanks for any help and suggestions.

Answer 1

I figured out what to do. I had to change:
<dict>
<key>UTTypeConformsTo</key>
<array>
<string>public.data</string>
</array>
<key>UTTypeIdentifier</key>
<string>com.chichapps.MTG-Binder.csv</string>
<key>UTTypeTagSpecification</key>
<dict>
<key>public.filename-extension</key>
<string>csv</string>
<key>public.mime-type</key>
<string>application/MTG-Binder</string>
</dict>
</dict>
To:
<dict>
<key>UTTypeConformsTo</key>
<array>
<string>public.data</string>
</array>
<key>UTTypeIdentifier</key>
<string>com.chichapps.MTG-Binder.csv</string>
<key>UTTypeTagSpecification</key>
<dict>
<key>public.filename-extension</key>
<string>csv</string>
<key>public.mime-type</key>
<string>application/csv</string> //Changing this fixed the problem
</dict>
</dict>