Difference between [[NSDate date] retain] and [[NSDate alloc] init]

Question

As both of the following serves the same purpose,

today = [[NSDate date] retain];    

and

today = [[NSDate alloc] init]; 
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Answer 1

Most of the time, when a class has an autoreleased initializer - it looks like this:

return [[[NSDate alloc] init] autorelease];

So when you call [[NSDate date] retain];, you are effectively calling

[[[[NSDate alloc] init] autorelease] retain];

Which, if you ask me, is fairly pointless - I'd just stick to [[NSDate alloc] init]; for initializing objects.

The convinience method is there so you can quickly get an autoreleased object - not to be used in conjunction with retain. It will do the same, but I would say it's better just to call the standard initialiser if you want a retained object.