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Editorial Team
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Asked: 2026-06-10T13:16:31+00:00

I develop application for iPad 3 – with Retina display. I calculated, based on

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I develop application for iPad 3 – with Retina display. I calculated, based on specification, that image should be 1536 x 2008 to fill (with a statusbar) entire screen. I resized image to such dimensions, and I programmatically load it and sets it to display on UIImageView (loaded from storyboard). What is more, to get best performance I set up UIImageView mode to Center (to avoid scaling). When I run app I see only center of my image – as if my image was 4 times the screen – which is not true.

Hers my code of viewWillAppear method

UIImage *image = [UIImage imageWithContentsOfFile: self.pageData.pageFilename];

NSLog(@"Image size: %f %f", [image size].width, [image size].height);

NSLog(@"Image view size: %f %f", self.imageView.frame.size.width, self.imageView.frame.size.height);

[ self.imageView setImage: image];

And I get in output:

Image size: 1536.000000 1990.000000
Image view size: 768.000000 1004.000000

How to correct this? My image is JPG with size you can see, and 72 DPI – but I’m sure that DPI doesn’t matter

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1 Answer

  1. Editorial Team

    You are mixing up pixel and points.

    In iOS dimensions are measured in points, not in pixles. If the device uses retina display, then 1 point = 2 pixel. Using the old display you have 1 point = 1 pixel.

    Normal display
    1 point = 1 pixel
    1024 * 768 points
    1024 * 768 pixel

    Retina display
    1 point = 2 pixel
    1024 * 768 points
    2048 * 1536 pixel

    So in both cases the size of the display has the same size:
    1024 * 768 points

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