Not understanding sentence and the importance of @class


Hi Please expalain this sentence to me:

also about @class does it matter if i use @class to declare a super class in a sub class and the other way around?
Like Im using @class BNRPerson in BNREmployee.h file.
Does it with that way?


If you are asking “can I subclass a class by only forward declaring it?” the answer is no.

You can’t forward declare a class and then create a subclass from it:

// FooBar.h

@class Bar;

@interface FooBar: Bar // Error: we do not know enough about Bar to subclass.

[/code]You must import the header file which contains the declaration of Bar:

// FooBar.h

#import "Bar.h"

@interface FooBar: Bar


However, if you are only declaring an instance variable or a property, a forward declaration in the header file is sufficient:

// FooBar.h

@class Bar;

@interface FooBar: NSObject
   Bar *_bar;

[quote]Hi Please expalain this sentence to me:

Imagine that you have an array of objects which you can modify by adding objects to it or by removing objects from it.
Now if I ask you to give that array to me, you make a copy of it and pass the copy to me. Therefore if I modify the array I received from you, your array remains intact; or if you change yours, my array remains intact.


Ibex when did I/you modify the array?
Can you tell me which line of code modify the array?


[quote]Can you tell me which line of code modify the array?
An array gets modified when you add an object to it or when you delete an object from it.

Look for a line of code which looks like this:

[someArray addObject:someObject];

See the NSMutableArray Class Reference for other methods that modify an array.