I am surprised to find that even by 2012 Apple has yet to include an object type for UUID. Nor do they provide an easy way to generate a UUID. Java does both.
The blog post Creating a GUID or UUID in Objective-C by Don McCaughey provides source code for a nice method to wrap Apple's clumsy UUID feature in Core Foundation. Unfortunately his 2010 code is not working for me Xcode 4.4.1, apparently because of ARC.
Cast of C pointer type 'CFStringRef' (aka 'const struct _CFString *') to Objective-C pointer type 'NSString *' requires a bridged cast
Two fix-its offered. I chose this one:
Use CFBridgingRelease call to transfer ownership of a +1 'CFStringRef' (aka 'const struct _CFString *' into ARC
And I deleted his call to autorelease.
Here is my revision to Mr. McCaughey’s code. My revision seems to be working. But is memory managed correctly? I am still too new to Objective-C and C to grasp the nuance of bridging OOP and POC (Plain Old C). Please post corrections or criticism.
// Return a new UUID string. Built for ARC in iOS 4 and later.
- (NSString *)generateUuidString
// create a new UUID which you own
CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
// create a new CFStringRef.
NSString *uuidString = (NSString *)CFBridgingRelease(CFUUIDCreateString(kCFAllocatorDefault, uuid));
// release the UUID
StackOverflow.com has a thread on this topic.