在代码中指定图像时，不使用Retina图标（@ 2x）

I place a play.png image onto my view. When the view initially loads, the iPhone 4 grabs the corresponding [email protected] file and it looks great. However, when I tap the play button my code swaps it out for the pause.png file. Then, when I tap the pause.png to bring back the play.png it uses the original play.png file (not the @2x version like I thought it would automatically reference).I place a play.png image onto my view. When the