Tell Android to open a particular file type in your Xamarin.Android app

FooFileActivity.cs

using Android.App;
using Android.Content;

// Tell Android to open a particular file type in your Xamarin.Android app

// Different apps will produce different intents for the same file, so
// you will need multiple intent filters to handle all the cases.
// You can look in the `adb logcat` logs to see which intent appears
// after you have tapped on a file in an app.

namespace AndroidApplication1
{
    [Activity(Label = "FooFileActivity")]
    //
    // Example Intent for link in web browser:
    // START u0 {act=android.intent.action.VIEW dat=http://www.example.com/test.foo typ=application/octet-stream}
    //
    // Example Intent for link in e-mail:
    // START u0 {act=android.intent.action.VIEW dat=http://www.example.com/test.foo flg=0x90000}
    //
    [IntentFilter(new string[] { Intent.ActionView },
        Categories = new string[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
        DataScheme = "http",
        DataHost = "*",
        // Double-escape the backslashes in C# so they end up
        // single-escaped in the generated manifest file
        // `obj/Debug/android/AndroidManifest.xml`
        DataPathPattern = ".*\\\\.foo"
    )]

    //
    // Example Intent from tapping attachment in Email app
    // START u0 {act=android.intent.action.VIEW dat=content://com.android.email.attachmentprovider/1/1/RAW typ=application/foo flg=0x80001}
    //
    [IntentFilter(new string[] { Intent.ActionView },
        Categories = new string[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
        DataScheme = "content",
        DataHost = "*",
        DataMimeType = "application/foo"
    )]
    public class FooFileActivity : Activity
    {
    }

    [Activity(Label = "DownloadsGmailAppsFileActivity")]
    //
    // Example intent from tapping file in Downloads app
    // START u0 {act=android.intent.action.VIEW dat=content://downloads/all_downloads/1 typ=application/octet-stream flg=0x3}
    //
    // Example Intent from tapping attachment in Gmail app
    // START {act=android.intent.action.VIEW dat=content://gmail-ls/[email protected]/messages/4/attachments/0.1/BEST/false typ=application/octet-stream flg=0x80001 u=0}
    //
    // This IntentFilter isn't so useful because it will match _any_ file
    // that has the "application/octet-stream" MIME type, not just `foo`
    // files.
    // 
    [IntentFilter(new string[] { Intent.ActionView },
        Categories = new string[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
        DataScheme = "content",
        DataHost = "*",
        DataMimeType = "application/octet-stream"
    )]
    public class DownloadsGmailAppsFileActivity : Activity
    {
    }
}

IN the first intent filter that has

DataPathPattern = ".*\\\\.foo"

I believe that is incorrect as you are escaping the backslash twice which if reading this correctly will yield:

\<anysinglecharacter>foo

To escape the ., match any path that ends with .foo I think this would be the correct format:

DataPathPattern = ".*\\.foo"

worked for me thanks,