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iOS Build a Simple iPhone App (iOS7) Refactoring into a Model Creating a Custom Class

Posted by aseem hegshetye
aseem hegshetye
Courses Plus Student 1,378 Points

is there a different between self.quotes and _quotes?

If i have a property in .h file called NSArray quotes. Then in .m file I can access it as self.quotes. Is it the same as saying _quotes. thanks

3 Answers

Alex Cevallos
Alex Cevallos
16,551 Points
Alex Cevallos
Alex Cevallos
16,551 Points

The reason that is happening is because

_quotes = @"hi how are you" means you are accessing the instance variable and assigning it that string

NSLog(@"%@", self.quotes) means you are accessing the property

If you want the exact specifics I would recommend reading up on "differences between objective c properties and instance variables"

here is a good link: http://stackoverflow.com/questions/843632/is-there-a-difference-between-an-instance-variable-and-a-property-in-objecti

Alex Cevallos
Alex Cevallos
16,551 Points

if you need any more help, just ask !

Alex Cevallos
Alex Cevallos
16,551 Points
Alex Cevallos
Alex Cevallos
16,551 Points

yep!

with self.quotes you access the property

with _quotes you access the class instance variable

aseem hegshetye
aseem hegshetye
Courses Plus Student 1,378 Points

but i tried _quotes=@"hi how are you"; and NSLog("%@",self.quotes); it was the same

aseem hegshetye
PLUS
aseem hegshetye
Courses Plus Student 1,378 Points
aseem hegshetye
aseem hegshetye
Courses Plus Student 1,378 Points

so if i call self.quotes from main - it will call quotes properties getter. if i call a xyz function from main which calls self.quotes in it.. i will get a value that is set for that object in main. if i call _quotes from main .. I cant call it lol.

printing function is in my quotes class

-(void) printing{ NSLog(@" %@",self.quotes); NSLog(@" %@",_quotes); }

in main () i havent set a value for object.quotes. when i call object.printing-- it gives me null for self.quotes but gives me a value for _quotes.. So i understand both are different but still i dont get the exact logic.

DOes it mean that _quotes is a class variable.. it has one value irrespective of what object is calling it. and self.quotes is object specific?

thanks