Appcelerator - save an image to external storage on Android 8

Question

I'm trying to save an image to external storage on Android 8.0.0 but the write always fails, the code works fine on Android below 8. I've requested the storage permission, the app has permission to read and write to external storage

var imageBlob = Ti.Filesystem.getFile(Ti.Filesystem.externalStorageDirectory, "test.png");
   var external = Ti.Filesystem.getFile(Ti.Filesystem.externalStorageDirectory);
   if (Ti.Filesystem.isExternalStoragePresent()) { //returns true
       Ti.API.info("external storage present");
       if (!external.exists()) { //returns false
           if (external.createDirectory()) { //returns false
               Ti.API.info("directory created");
           } else {
               Ti.API.info("error creating dir");
           }
           Ti.API.info("external.exists= " + external.exists());
       }else{
          var f = Ti.Filesystem.getFile(Ti.Filesystem.resourcesDirectory, "original.png");
          if(file.exists()){ //returns true
              if(imageBlob.write(file.read())){ //returns false
                Ti.API.info("image saved");
              }
          }
       }
   }

Edit: Thanks to the help of one of TiSlack members I was able to solve the issue instead of using Ti.Filesystem.requestStoragePermissions to request storage permission I used

var permissions = ['android.permission.WRITE_EXTERNAL_STORAGE'];
Ti.Android.requestPermissions(permissions, function(e) {...})