Question

I know that you use @synthesize to create setter and getter methods, which makes things easier because then you don’t have to write your own.

There are certain places where you have to use self.property instead of just property in order to make use of the setter and getter methods, such as in dealloc and initWithCoder.

This tells me that these setter and getter methods are doing something else that’s important, besides making it easier for you to set and get a variable. What are they doing and how do they do it?

Answer 1

They’re doing whatever you told them to do in the @property statement or your own implementation, if you chose to write one. Most often, the reason for using the accessors rather than directly modifying instance variables is to avoid memory leaks. Imagine an NSString instance variable declared with

@property (nonatomic, retain) NSString *myString;
@synthesize myString;

These lines generate an accessor that correctly calls release and retain when you want to change the myString property of an object. If you didn’t call the accessor, you could potentially leak the old value, unless you were careful to do the memory management yourself.