The Fundamentals

Question 1

what is let and var in Swift?

Answer 1

let is used to declare constant and var is used to declare variable

Question 2

What is the difference between structs and classes?

Answer 2

Classes reference type. Structs are value types.

Question 3

How is memory management handled in iOS?

Answer 3

Swift uses automatic reference counting (ARC). ARC keeps track of strong references to instances of classes and increases or decreases their reference counting on assign and unassign.

Question 4

What is protocol in Swift?

Answer 4

Declarations of what a type that adopts them should implement. 
@objc - class only

Question 5

What is an extension and when is it used?

Answer 5

A way to extend the existing functionality of a class or type.
drawback - globally applied
be aware of - name conflicts

Question 6

What are closures/blocks?

Answer 6

Declare and capture a piece of executable code that will be launched at a later time

Question 7

What are the components of MVC for a typical iOS app?

Answer 7

1. UIView are the views
2. UIViewControllers are the Controllers
3. any data objects, NSManagedObject subclasses are models

Question 8

What are Singletons?

Answer 8

A class that returns only one-and-the-same instance no matter how many times you request it

Question 9

What are 2 major disadvantages to using singletons?

Answer 9

1. global state and object lifecycle

2. dependency injection

Question 10

What is Delegate pattern?

Answer 10

A variation of the Observer pattern where only one object can observe events coming from another object