Difference between encapsulation and abstraction.

Ans :

Encapsulation hides variables or some implementation that may be changed so often in a class to prevent outsiders access it directly. They must access it via getter and setter methods.

Abstraction is used to hiding something too but in a higher degree(class, interface). Clients use an abstract class(or interface) do not care about who or which it was, they just need to know what it can do.

Encapsulation: Wrapping code and data together into a single unit. Class is an example of encapsulation, because it wraps the method and property. 

Abstraction: Hiding internal details and showing functionality only. Abstraction focus on what the object does instead of how it does. It provides generalized view of classes.

int number = 5;
string aStringNumber = number.ToString(); 

Here, ToString() is abstraction. And how this mechanism number variable converted to string and initialize into aStringNumber is encapsulation.

We can achieve abstraction using protocol in iOS, achieve encapsulation using access control in class or struct.