All is in the question, I've worked enough with cocos2d to say it's a great library but today I only wanna use particle system in a total UIKit project. As long as I know, unfortunately, I have to implement one with OpenGL. Any suggestions ?
You can use Core Animation and CAReplicatorLayer to generate particle systems without having to drop down to OpenGL ES. Joe Ricioppo's "To 1e100f And Beyond with CAReplicatorLayer" gives an introduction to how to use this class. Also, Apple has their ReplicatorDemo sample application, which I ported to the iPad.
On the Mac, there's also the CAEmitterLayer, which became available in iOS as of 5.0. Apple's sample applications for this include Fire, which shows off fire and smoke effects, and Fireworks, which simulates a fireworks display.