This keyword vs self

Not sure if this was what you where asking~

Look at:

+http://answers.oreilly.com/topic/1193-calling-self-object-rather-than-calling-the-object-directly-in-objective-c/

+http://useyourloaf.com/blog/2011/02/08/understanding-your-objective-c-self.html

self.name uses the accessor and/or mutator defined by you (this is nonatomic and retain in your case). So when you call self.name = foo, it will call the setName:(NSString *)str mutator generated by the compiler, which will first release the current string, then retains the new string and finally sets name to the retained string.

Just calling name = foo does nothing more than assigning name to foo.

This also means that you can only call self.xxx when you have defined a property for the ivar, otherwise the compiler will tell you that it doesn't know about it(iVar).

self.attribute goes through the object's getter or setter function, as appropriate. That allows you to set up initial values, trigger update messages, or anything else.

Accessing "attribute" directly goes straight to the underlying variable, so you bypass all that. As a result, it's definitely the less-preferable way of working.

There are certain circumstances where it's generally discouraged to use the self.-expression to access a property. Normally you always use self for any access of a property. It's the most secure and uncomplicated way. Especially if you used retain, then memory management will be done for you.

The two exceptions from this rule:

+Any init method.

+In dealloc.

In both cases you are dealing with an partially initialized object. There are some side effects that may occur when using setters or getters here -- because they are methods and hence may be overridden.

For example, take a class A with a property foo that has been subclassed by class B. The subclass B adds an property bar and overrode the setter for foo. Now your init-method calls setFoo:, because you used self.foo = ... with some initial value. The subclass, however, also accesses the value of bar in this setter. But in this case, it may happen that bar has never been initialized and points at some arbitrary data. Calling a setter in init my cause crashes, although the probability may not be too high in your own code.