This example is from Birkenmose, a member of the Cocos2D forum. They have posted a “RippleSprite” class which works very much like a CCSPrite and with just a few lines of code you can add this ripple effect to an image.

Birkenmose has also done an excellent job of explaining everything that is going on in the code with his comments which is of great help.

✔ Demo

Via Vincent Demay