Question

So I’m using NSClassFromString to check if the user has iOS 5 or iOS 6 installed to use Apple’s new iOS 6 MKMapItem. This is the code:

- (void)openDirections:(id)sender {
    Class mapClass = NSClassFromString(@"MKMapItem"); 

    if (mapClass == nil) {
    // iOS 5, do something here
    }
    else {
    // iOS 6, open up maps with MKMapItem.
    }
}

By the code above, when I run it on iOS 5.1 simulator or a iOS 5.1 device, the iOS 6 branch gets run. However, if I use

Class mapClass = NSClassFromString(@"PKPass");

which was also introduced in iOS 6, my code follows the appropriate iOS 5 or iOS 6 branch. Am I missing something? Thanks.

Answer 1

MKMapItem exists in prior versions of iOS because it was in development then, therefore the class existed. Instead, Apple recommends that you should use the following code also checking for a method they specifically added in iOS 6.0:

Class itemClass = [MKMapItem class];
if (itemClass && [itemClass respondsToSelector:@selector(openMapsWithItems:launchOptions:)]) {
   // Use class
}

Information from MKMapItem Class Reference