XML : Using RelativeLayout to offset center align ProgressBar view?

I've an ImageView that serves as the background of the image and at the same time a preloader horizontally and vertically aligning in the center of the screen. I managed to center the progressBar but wasn't able to offset it slightly above using margin.

Some people suggested to use linearLayout and control using android:layout_weight, however it doesn't work for me as I need to apply my image as background and hence the relativeLayout...

  <?xml version="1.0" encoding="utf-8"?>  <RelativeLayout  xmlns:android="http://schemas.android.com/apk/res/android"            android:orientation="vertical"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:gravity="center"            android:background="#FE6869"            android:weightSum="1">    <ImageView      android:src="@drawable/splashscreen"      android:scaleType="centerCrop"      android:layout_width="match_parent"      android:layout_height="match_parent" />      <ProgressBar      android:id="@+id/loading_spinner"      style="@style/Widget.AppCompat.ProgressBar"      android:layout_width="65dp"      android:layout_height="65dp"      android:layout_centerVertical="true"      android:layout_centerHorizontal="true"      android:layout_marginTop="170dp" />      </RelativeLayout >