How to center two views using view.frame and view.center

I am trying to do something pretty basic here. I am using a block-based UIView animation to bring the subview that is currently off the screen to the current view's center. Obviously the sp.view.frame = self.view.center line is the issue here. In the end, how do I do what I want?

[UIView animateWithDuration:1 delay:0
                    options:UIViewAnimationOptionCurveLinear
                 animations:^{
    sp.view.frame = self.view.center;        
}

Thanks!