Open Radar

 
Summary:
Since Xcode 7 we have ability to use lightweight generics that come pretty handy and especially in Objective-C++ where we can use “auto” keyword to avoid typing pretty long typename declarations. 

Unfortunately “auto” keyword does not work properly with lightweight generics in for-in loops and unable to resolve element type of iterated array and falls back to “id”.

Compiler must be able to resolve the typename of object in iterated array. 

NSFastEnumeration, on the other hand, works properly and Xcode suggests the right typename when using enumerateObjectsUsingBlock.

Example: 

   NSArray<UILocalNotification *> *localNotifications = [[UIApplication sharedApplication] scheduledLocalNotifications];
    
    for(auto notification in localNotifications) {
        if([notification.userInfo[@"isGameActivityNotification"] boolValue]) {
            [[UIApplication sharedApplication] cancelLocalNotification:notification];
        }
    }

Steps to Reproduce:

Expected Results:
“auto” is deduced as “element type” of iterated array.

Actual Results:
Compiler throws warning “‘auto’ deduced as ‘id’ in declaration of ‘notification’”

Regression:

Notes: