check if a folder exists uwp xamarin.forms

Question

i am trying to create a folder in the downloads folder using uwp, and in this folder i want to create pdf files. this is what is supposed to happen: the first time the button is clicked, the folder is created and so is a pdf file corresponding to a client. on the second button click, the folder must be checked to be existed, and so only the pdf file should be created inside it. the thing is that my code, without the part where it checks for folder existence, works on the first click, but doesn't work on the second because i get an exception that the folder already exists. but with the 'if' part, it doesn't work at all. like nothing is created. here is my code:

[assembly: Dependency(typeof(getpathUWP))]
namespace ALNahrainAlphaApp.UWP
{
    public class getpathUWP : path
    {
        public Task< string> get_path(string foldername, string filename, byte[] ar)
        {
            Task<string> t = Task.Run(() => pathtoget(foldername,filename,ar));

            return t;
           

        }

       

        async private Task<string> pathtoget(string foldername, string filename, byte[] ar )
        {
            //  StorageFolder newFolder = null;
          
            if (!File.Exists(@"C:\Users\ALNOOR\Downloads\d98cfcb0-e3cb-48e3-b720-fd9ace0ca7e8_htzz2mrv9gx22!App\alnahrainfiles"))
            {
                StorageFolder folder = await StorageFolder.GetFolderFromPathAsync(@"C:\Users\ALNOOR\Downloads\d98cfcb0-e3cb-48e3-b720-fd9ace0ca7e8_htzz2mrv9gx22!App\alnahrainfiles");
                StorageFile file = await folder.CreateFileAsync(filename);
                Stream stream = await file.OpenStreamForWriteAsync();
                stream.Write(ar, 0, ar.Length);
                stream.Flush();
            }
               
           

              
            else 
            {
                StorageFolder newFolder = await DownloadsFolder.CreateFolderAsync(foldername);

                StorageFile file = await newFolder.CreateFileAsync(filename);
                Stream stream = await file.OpenStreamForWriteAsync();
                stream.Write(ar, 0, ar.Length);
                stream.Flush();
            }

            return "";
           
        }
        }
}

note that i am using a dependency service. i tried other ways to check if the folder exists, but nothing is working. what am i doing wrong?

Answer 1

this will open the folder if it exists, or create it and open it if it does not

StorageFolder newFolder = await DownloadsFolder.CreateFolderAsync(foldername, CreationCollisionOption.OpenIfExists);

Answer 2

The File.Exists method is to check if the specified file exists. You said you need to check if the folder exists, you can use the Directory.Exists method to determine if the directory exists.