When should I use @synthesize explicitly?

Question

As far as I know, since XCode 4.4 the @synthesize will auto-generate the property accessors. But just now I have read a sample of code about NSUndoManage

Answer 1

If you do not explicitly use @synthesize the compiler will understand your property the same way if you had written

@synthesize undoManager=_undoManager;

then you will be able to write in your code things like :

[_undoManager doSomething]; // iVar
[self.undoManager doSomethingElse]; // Use generated getter

This is the common convention.

if you write

@synthesize undoManager;

you will have :

[undoManager doSomething]; // iVar
[self.undoManager doSomethingElse]; // Use generated getter

Personally I stop using @synthesize, since it's not mandatory any more. For me the only reason to use @synthesize is to link an iVar to a @property. If you want to generate specific getter and setter for it. But in the given piece of code there is no iVar, I think that this @synthesize is useless. But now I think the new question is "When to use iVar ?", and I've no other response than "never" for this one !