Added new SpriteKit tutorial: Drag & Drop
Added images for the tutorial
Added two variables for the background and the selected node
Added a constant
Clean up
Added the background.
Refactoring...
Refactoring: changed init method
Changed the application to work only in landscape mode
Adding the images to the screen
Modified the background and the image's position
Get the position of the touch
Function for selecting a node based on the position
Wiggle animation when you touch the animal
Added a function for confer a degree to radiants
Fixed function for converting the degrees to radiants
Set the new position for the animal
Some refactoring