How to specify FilePickerFileTypes for Xamarin.Essentials.PickOptions?

Question

I was trying the following code which greys .txt files. What's wrong with my specifying the file types?

        FilePickerFileType customFileType =
            new FilePickerFileType(new Dictionary<DevicePlatform, IEnumerable<string>>
            {
                { DevicePlatform.iOS, new[] { ".txt", ".tab", ".csv" } },
                { DevicePlatform.Android, new[] { ".txt", ".tab", ".csv" } },
                { DevicePlatform.UWP, new[] { ".txt", ".tab", ".csv" } },
            });

Answer 1

The following is the code that is working for Android & iOS:

        FilePickerFileType customFileType =
            new FilePickerFileType(new Dictionary<DevicePlatform, IEnumerable<string>>
            {
                { DevicePlatform.iOS, new[] { "public.text" } },
                { DevicePlatform.Android, new[] { "text/plain" } },
            });

For iOS, first I tried the following:

{ DevicePlatform.iOS, new[] { (string)MobileCoreServices.UTType.Text } },

Then checked the value set to customFileType. That is "public.text". Also "Text" covers all text files including .tab and .csv though separate enumerations are available for those types.

Still I have not yet tried for UWP project. That will take some more time for me.

Answer 2

Hi ShantimohanElchuri-8757,

Welcome to our Microsoft Q&A platform!

According to the document: PickOptions.FileTypes Property, we can know that

every platform has its own way to specify the file types.

On Android you can specify one or more MIME types, e.g.
"image/png"; also wild card characters can be used, e.g. "image/*".

On iOS you can specify UTType constants, e.g. UTType.Image.

On UWP, specify a list of extensions, like this: ".jpg", ".png".

So to filter the txt file, you can set the customFileType as follows.

FilePickerFileType customFileType =  
    new FilePickerFileType(new Dictionary<DevicePlatform, IEnumerable<string>>  
    {  
        { DevicePlatform.iOS, new[] { "UTType.Text" } },  
        { DevicePlatform.Android, new[] { "text/plain" } },  
        { DevicePlatform.UWP, new[] { ".txt"} }  
    });  

Regards,
Kyle

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