Sash Zats Sash Zats - 1 month ago 11
Objective-C Question

CFPropertyListCreateDeepCopy fails to process array / dictionary containing NSNull

For some reason this sample code works:

NSArray *immutable = @[ @"a", @"b", @"c" ];
NSMutableArray *mutable = (__bridge id)CFPropertyListCreateDeepCopy(kCFAllocatorDefault, (__bridge CFArrayRef)immutable, kCFPropertyListMutableContainers);


and this code produces
nil
as a result of the conversion:

NSArray *immutable = @[ @"a", [NSNull null], @"c" ];
NSMutableArray *mutable = (__bridge id)CFPropertyListCreateDeepCopy(kCFAllocatorDefault, (__bridge CFArrayRef)immutable, kCFPropertyListMutableContainers);


I tried to find any mention of
NSNull
not being allowed when using this function. I have a suspicion that it has something to do with the way method examines whether property is mutable or not, but I can't really back that up with facts.

Any ideas?

Answer

As kind people from apple developer forum pointed out the issue is that Property List Structure is rather strict about data types it can work with. NSNull is not one of allowed ones.

From apple docs:

Property lists are constructed from the basic Core Foundation types CFString, CFNumber, CFBoolean, CFDate, and CFData.