Hi, with the default values the rotation take place but changing the value not. I bind a button to a slider action: -(IBAction)rotateXAction:(id)sender { NSLog(@"%@ \n",sender); BOOL yn = YES; _rotationX = [_sliderX intValue]; if(yn) printf("rotationX %d \n",_rotationX); // value o.k [self setNeedsDisplay:YES]; } The drawRect: will not be called. What is wrong with my code, please tell me. Uwe