Access denied using mvxfilestore, mvvmcross annd xamarin touch ios 8.1

My app has just deviated from apple and I believe it might be because they change for testing with ios 8.1. However, there is no way I can reproduce the error. Their chrash report talks about applications on startup.

The exception (there is a crash log) seems to come from

<Warning> Unhandled managed exception: Access to the path "/var/mobile/Documents/settings" is denied. (System.UnauthorizedAccessException)

      

        
        
        
      

    

which is taken from

Cirrious.MvvmCross.Plugins.File.MvxFileStore.WriteFileCommon

      

        
        
        
      

    

I am using the mvvmcross 3.11 MvxFileStore plugin. Ios7 deployment target, 8.1 ios sdk.

I am surfing the web and some states of the Document Directory have moved to iOS 8 and this might throw an exception. But I can't wrap my head in that I can't reproduce this error.

Does anyone have a similar issue, suggestion to fix it, or figure out how to reproduce their crash.

Everyone is welcome.

Update:

The post suggests the following fix

int SystemVersion = Convert.ToInt16(UIDevice.CurrentDevice.SystemVersion.Split('.')[0]);
        if (SystemVersion >= 8)
        {
            var documents = NSFileManager.DefaultManager.GetUrls(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomain.User)[0].Path;
            filename = Path.Combine(documents, sFile);
        }
        else
        {
            var documents = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments); // iOS 7 and earlier
            filename = Path.Combine(documents, sFile);
        }

      

        
        
        
      

    

I tried to add it to our project. We used MvxFileStore to create the path to the settings file

 var filestore = Mvx.Resolve<IMvxFileStore>();
            string path = filestore.PathCombine(filestore.NativePath (string.Empty), FILENAME);

      

        
        
        
      

    

We will now define the following

 var filestore = Mvx.Resolve<IMvxFileStore>();
            string path = this.DocsDir() + "/" + FILENAME;

public string DocsDir ()
        {
            var version = int.Parse(UIDevice.CurrentDevice.SystemVersion.Split('.')[0]);
            string docsDir = "";
            if (version>=8) {
                var docs = NSFileManager.DefaultManager.GetUrls (NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomain.User) [0];
                docsDir = docs.Path;
                Console.WriteLine("ios 8++ "+docsDir);
            } else {
                docsDir = Environment.GetFolderPath (Environment.SpecialFolder.MyDocuments);
                Console.WriteLine("ios 7.1-- " + docsDir);
            }
            return docsDir;
        }

      

        
        
        
      

    

I will resubmit my application and post the result.