Button size becomes small in iphone sdk 4.0

I have done one app in iphone sdk 3.0 in that i use some butto开发者_JS百科ns in 3.0 size of button are fine but when i use that app in iphone sdk4.0.That time, size of button becomes small.The same button code works in 3.0 but not in 4.0.Please help.

Thanks

Some sample code would help. In general for iPhone 4 you just make a button image with twice the size and add "@2x" to the name, this will automatically be used for Retina display. So you would have "button.png" and "button@2x.png" in your project.