Question

Would anyone be able to explain to me what data encapsulation in Objective-C is? I’ve been told that this an important concept of Objective-C but I don’t see why…

Explain it to me as if I was 5 and then as if I was 25….

Thanks for your time,
~Daniel

Answer 1

From http://mobile.tutsplus.com/tutorials/iphone/learn-objective-c-2/ :

What we mean by data encapsulation is
that data is contained (so to speak)
by methods meaning to access it we
need to use methods. Some of you who
have programmed in other languages and
havenʼt heard of data encapsulation
may be wondering why we do things this
way. The answer is that by
encapsulating data, there is a nice
cushion between the developer of a
class and the user of a class. Because
the class methods manage and maintains
the attributes within the class, they
can more easily maintain data
integrity. Another major benefit is
that when a developer distributes his
class, the people using it donʼt have
to worry about the internals of the
class at all. A developer may update a
method to make it faster or more
efficient, but this update is
transparent to the user of the class
as he/she still uses the same method
with no change to his/her code.

In simple terms, the user is provided with what the developer wanted them to have, and “protects” everything else. The developer can change anything internal without the user having to rewrite their code.

If developers did not conform to data encapsulation, we would need to rewrite our code every time a new version of a library, code snippet, or an entire program was released.