Saving UIView contents in iOS 4 with real size of the images inside (i.e. scale contentes up for save)

Question

I have an UIView with many UIImageViews as subviews. The app runs on iOS4 and I use images with retina display resolution (i.e. the images load with scale = 2)

I wa

Answer 1

The key is that the third parameter to UIGraphicsBeginImageContextWithOptions is the scale, which determines how the image will ultimately be written out.

If you always want the real pixel dimensions, use [[UIScreen mainScreen] scale] to get the current scale of the screen:

UIGraphicsBeginImageContextWithOptions(viewSizeInPoints, YES, [[UIScreen mainScreen] scale]);

If you use scale=1.0 on iPhone4, you will get an image with its dimension in points and the result is scaled down from the true pixel count. If you manually write the image out to a 640x960 dimension (eg: passing pixels as the first parameter), it will actually be the scaled-down image that is scaled back up which looks about as terrible as you imagine it would look.