Use @2x retina images for ipad in universal app? and does apple prefer native apps?

Question

I know there were some discussions about this but i could not find good answer?

My questions are -

1. I know that -

     [UIImage imageNam         
   
   
           

Answer 1

I improved on Bogatyr's answer by checking if the retina image exists. Probably not overly necessary, but I found it useful when testing so I can just create one image file.

+ (UIImage *) imageNamedSmart:(NSString *)name {
    NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
    NSString *retinaFileName = [NSString stringWithFormat:@"%@@2x", name];

    NSString *filePath = [[NSBundle mainBundle] pathForResource:retinaFileName ofType:@"png"];

    if ( UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad && [fileManager fileExistsAtPath:filePath]) {
        return [UIImage imageNamed:[retinaFileName stringByAppendingString:@".png"]];
    }
    return [UIImage imageNamed:[NSString stringWithFormat:@"%@.png", name]];
}