Question

In Objective C what scenario would I want to use [self setVariable:value]; instead of variable = value;

It seems as if doing a self set I’m saving myself few lines of code, but what other advantages are there? Additionally, when would I NOT want to do a self set?

Answer 1

EDIT:
I should clarify, that what I am referencing below is strictly in regards to variables that are properties. If a variable is just an ivar, then there is no difference between self.variable = value or variable = value, other than the fact that self.variable = value will not even compile if it is just an ivar, in that case you need to use self->variable = value

Calling

[self setVariable:value];

is the same as calling

self.variable = value;

This, however, is NOT the same as

variable = value;

The first two cases use the synthesized setVariable method (or the one you defined yourself). The reason you would want to use this is to make sure you keep the proper retain count on your objects.

For example, a simple property such as:

@property (retain) NSString *myString;

Gets an automatically generated set function that looks something like:

-(void) setMyString:(NSString*)other
{
    myString = [other retain];
}

If you were to just call

myString = otherString;

elsewhere in your code, then myString is not retained properly, so if otherString gets deallocated, your pointer to that object is no longer valid.