NSPropertyListSerialization mutabilityOption not working for binary plists when not using ARC

[rupertdaniel]

When using NSPropertyListSerialization to create a mutable dictionary from a binary plist file and not using ARC, it does not return a mutable object.

Example:

// Load binary plist data
NSData *binaryPlistData  = [NSData dataWithContentsOfURL:[[NSBundle mainBundle] URLForResource:@"Data" withExtension:@"plist"]]; 

// Create mutable dict from data
NSMutableDictionary *d = (NSMutableDictionary *)[NSPropertyListSerialization propertyListFromData:binaryPlistData mutabilityOption:NSPropertyListMutableContainers format:NULL errorDescription:nil];

// Try to add object
[d setObject:@"test" forKey:@"object"];  // Raises exception about not being mutable

Doing the same under ARC returns a mutable dictionary as expected.