How to set an image based on iphone platform in objective-c

Question

I'm moving my application from 3.x to 4.x as I prepare for the app store and found that I need to have 2 copies of all my custom pngs - my question is how can I determine what img to show and when. Example - how do I know to show the Find.png vs the Find@2x.png

Is it "safe" or "correct" to look for 4.x specific apis or does the iphone have a way to determine what platform you are on at runtime?

Thank you in advance

score 3 · Accepted Answer · answered Feb 23 '11 at 23:26

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When you use standard APIs, the phone handles grabbing the @2x version when necessary. For example if you use [UIImage imageNamed:@"Find.png"]; and run on an iPhone 4, it would load Find@2x.png automatically.

answered Feb 23 '11 at 23:26

Ben Cochran

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I assume interface builder does the [UIImage imageNamed:@"Find"]; and does the @2x for free? correct? – Toran Billups Feb 23 '11 at 23:48
Yes, images added in Interface Builder also have the automatic @2x behavior. – Ben Cochran Feb 23 '11 at 23:50

score 1 · Answer 2 · edited May 23 '17 at 12:29

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[[UIDevice currentDevice] model];
[[UIDevice currentDevice] systemName];
[[UIDevice currentDevice] systemVersion];

Detect retina screen/iPhone 4 in iPhone SDK

edited May 23 '17 at 12:29

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answered Feb 23 '11 at 23:26

Erick Smith

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score 1 · Answer 3 · edited May 23 '17 at 11:55

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If you use the imageNamed: method of UIImage the @2x business is handled for you.

Otherwise you can check the scale of the screen as in this question

edited May 23 '17 at 11:55

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answered Feb 23 '11 at 23:27

Alex Deem

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score 1 · Answer 4 · answered Feb 23 '11 at 23:27

If your application is running on (I believe) iOS 4.2 or greater and the images are PNG files you can replace you calls of:

[UIImage imageNamed:@"Find.png"];

with simply:

[UIImage imageNamed:@"Find"];

On the later versions of the OS imageNamed attempts to treat the incoming parameter as a root name to an image instead of the specific image name itself. In such a case it has the intelligence built-in to load the graphic most appropriate for the device.

How to set an image based on iphone platform in objective-c

4 Answers4