centering a CGRect in a view

I have an image displaying in a CGRect. how do I center the rect in the view?

here's my code:

UIImage * image = [UIImage imageNamed:place.image];
CGRect rect = CGRectMake(10.0f, 90.0f, image.size.width, image.size.height);

UIImageView * imageView = [[UIImageView alloc] initWithFrame:rect];
[imageView setImage:image];

I've tried imageView.center but to no effect.

thanks in advance.