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Image management in the universal iphone / ipad app

I'm just wondering what techniques people are using to dynamically use larger or smaller images in their universal iPhone / iPad apps.

I created a large test image and I tried to scale down (using cocos2d) by 0.46875. After watching this in the iPhone 4.0 simulator, I found the results were pretty crappy ... rough pixel edges, etc. Also, downloading huge image files for iPhone users when they don't need them is pretty lame.

So, I think what I probably have to do is save two versions of each sprite ... large (for iPad) and small (for iPhone / iPod Touch), then detect the user device and spit out the proper sprite:


NSString *deviceType = [UIDevice currentDevice].model;
CCSprite *test;
if([deviceType isEqualToString:@"iPad"]) {
  test = [CCSprite spriteWithFile:@"testBigHuge.png"];
} else {
  test = [CCSprite spriteWithFile:@"testRegularMcTiny.png"];
}
[self addChild: test];

How do you guys do it? I would rather avoid using all my code with statements like this. I also want to avoid using .xib files as this is an OpenGL based application.

Thanks!

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3 answers


I wrote a little hint for macros:


#define deviceFile(file, ext) \
  ([[UIDevice currentDevice].model rangeOfString:@"iPad"].location != NSNotFound ? \
    [NSString stringWithFormat:@"%@-iPad.%@", file, ext] : \
    [NSString stringWithFormat:@"%@.%@", file, ext])


Using:


// outputs either "test.png" or "test-iPad.png" depending on the user device
CCSprite *test = [CCSprite spriteWithFile:deviceFile(@"test", @"png")];
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Specify each image in sequence with "Large" or "Small", but keep the other names the same for equivalent images.

There is a global value somewhere with the @ "Large" or @ "Small" value that you set at startup.

There is a method somewhere that will take a generic name string and insert a global size specifier.



@interface CCSprite (MyProject)
+(id) spriteWithSizedFile:(NSString *)inName;
@end

@implementation CCSprite(MyProject)
+(id) spriteWithSizedFile:(NSString *)inName {
  return [CCSprite spriteWithFile:[gSizeSpecifier stringByAppendingString:inName]];
}
@end

Possibly a better spot than CCSprite. This is just an example.

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#define M_IS_IPAD (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
and make a function like this

   +(id)BooL
{
   if(M_IS_IPAD)
  {
      return true;
  }
  else
  {
    return false;
  }

}

use this anywhere :) and change the images for ipad or ipod accordingly ....

Regards: shauket

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