looking if there is a pause/resume method in this class.
something like :[CCParticleSystemQuad resume];
do I missing ? or not exists ?
Not officially. But you could edit the source code, add a BOOL property paused and check the paused flag in the update method:
-(void) update:(ccTime)delta
{
if (_paused == NO)
{
// update particles code here...
}
}
No guarantee that it'll work but it's worth giving it a try.
It might also be possible without changing the code, but this will affect other scheduled methods and actions too:
[particleSystem pauseSchedulerAndActions];
To resume:
[particleSystem resumeSchedulerAndActions];