Setup an app to detect OS ver. and iPhone or iPad

Question

1. How can I detect whether my app is running on an iPhone or iPad, and what OS version it is running?
2. Can I use pre-processor macros in a similar fashion to #if _OS4.0 or #if IPAD or something of the sort?
3. Is this kosher, or should I just make separate builds for submission?

Answer 1

The UI_USER_INTERFACE_IDIOM() can be used to detect the device. Possible return values are:

• UIUserInterfaceIdiomPhone
• UIUserInterfaceIdiomPad

if( UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad ) {}

There's also the __IPHONE_3_2 define that can help:

#ifndef __IPHONE_3_2
    /* ... */
#elif
   /* ... */
#endif

Answer 2

Generally using features based on OS version is bad practice.

As offered, use UI_USER_INTERFACE_IDIOM() whenever possible. Also use:

Class qlPreview = NSClassFromString(@"QLPreviewController");

and

UIScreen *mainScreen = [UIScreen mainScreen];
if([mainScreen respondsToSelector:@selector(scale)]){
     NSLog(@"screen scale: %f",[mainScreen scale]);
}

However, sometimes you can't avoid it checking for system version.

Answer 3

http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIDevice_Class/Reference/UIDevice.html#//apple_ref/occ/instp/UIDevice/model