UIButton image and retina display

I have some button with custom background image, and here is how I do this:

UIImage *buttonImage2Normal = [UIImage imageNamed:@"greyButton.png"];

[showModal setBackgroundImage:buttonImage2Normal
                                        forState:UIControlStateNormal];

UIImage *buttonImage2Pressed = [UIImage imageNamed:@"greyButtonPressed.png"];

[showModal setBackgroundImage:butt开发者_StackOverflow社区onImage2Pressed
                                        forState:UIControlStateHighlighted];

And I made four images, greyButton.png, greyButtonPressed.png and @2x versions to support retina.

But, on retina (iPhone simulator) I see ok my buttons, but on iPhone (3G) I think that is uses bigger images because my buttons are almost without rounded corners.

This is the right method for doing this?

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You are doing it correctly as long as you name your Retina Display images like this: filename.png and filename@2x.png

You might want to simply test by making a non-Retina image that's a red colour, then a Retina image that's a blue colour.

On iPhone Simulator with Retina scale you should be seeing a blue button and on your 3G iPhone you should be seeing a red button.