Question

I understand that the Retina display has 2x as many pixels as the non retina displays, but what is difference between using the @2x version and taking and taking the 512 x 512 image and constraining it via the size of the frame ?

To Clarify:

if I have a button that is 72 x 72 The proper way to display that on an iPhone is to have a

image.png = 72×72

[e-mail] = 144 x 144 <—Fixed 🙂 TY

But why not just use 1 image:

image.png = 512×512

and do something like this:

UIImageView *myImage = [[UIImageView alloc] init ];
[myImage setImage:[UIImage imageNamed:@"image.png"]];
[myImage setFrame:CGRectMake(50, 50, 72, 72)];

I am sure there is a good reason, I just dont know what it is, other then possibly a smaller app file size?

Thanks for the education!

Answer 1

There are several good reasons for sizing your images correctly, but the main one would have to be image clarity: When resizing images, you often end up w/ artifacts that make a picture look muddy or pixelated. By creating the images at the correct size, you’ll know exactly what the end user will see on his or her screen.

Another reason would simply be to cut down on the overall file size of your binary: a 16×16 icon takes up orders of magnitude fewer bytes than a 512×512 image.

And if you need a third reason: Convenience methods such as [UIImage imageWithName:@”xxxx”] produce images of actual size and usually do not need additional frame/bounds code to go along with them. If you know the size, you can save yourself a lot of headache.