iOS Retina display: images double size - iphone

Question

For testing not/retina display I've created an UIView with size 100x100.
I've create 2 images:
- normal size (100x100)
- retina size (200x200)
I have two situations:
1) Non-Retina display + Normal Size image in background
2) Retina display + Retina Size image in background
The 1st scenario is ok.
In the 2nd scenario the image is double size and in my UIView I can see only 1/4 of the total image.
The same happens when I try to assign a background image to my UIViewController navigation bar as following:
if (IS_RETINA()) {
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:IMG_NAVIGATION_BAR_BACKGROUND_RETINA] forBarMetrics:UIBarMetricsDefault];
}
else {
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:IMG_NAVIGATION_BAR_BACKGROUND] forBarMetrics:UIBarMetricsDefault];
}

Answer 1

There's a much easier way to do this. Give the retina version of the image the same name as the non-retina version, except with a "#2x" at the end. For example, if your regular image was named foo.png, then the retina version should be named foo#2x.png.
Then, just refer to the regular version of the filename (e.g., foo.png) at all times. When your app is running on non-retina hardware the regular image will be used, but whenever you're on retina hardware the higher-resolution image will be used automatically. It's easier than having to write an if statement for every image you use, plus it'll actually work.

Answer 2

You don't need to code the IS_RETINA test, just add the #2x suffix to the name of the file containing the image you want to use for the retina display, and iOS will automagically use that in preference.
Bundle 2 image files, prettyNavBarBackground.png and prettyNavBarBackground#2x.png
#define IMG_NAVIGATION_BAR_BACKGROUND prettyNavBarBackground
Then you can just use this single call, and iOS will select the appropriate option
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:IMG_NAVIGATION_BAR_BACKGROUND] forBarMetrics:UIBarMetricsDefault];

Answer 3

U don't have to write any sought of code to distinguish between retina and normal hardware. U just need to add a "#2x" image . This will work fine as perfect.
U don't have to call these images individually, but just write the filename.