You have to just make some small changes to use this source code like:
1. Change all Images with your images in Image Bundle (name of the Image is the Answer so don't write it wrong else your app will not give right answers)
2. You have to put all images with name of its answer for example: if You add Flag of England then you have to Save image name as england.png.
3. Put all images in Level#1 Bundle.
4. Also you can add more levels as you want