Beyond MVC. Design Pattens, Architecture, FRP, and Dependencies Management.

Question 1

What design patterns are commonly used in iOS apps?

Answer 1

MVC, Singleton, Delegate, Observer

Question 2

What is MVC?

Answer 2

1. Models being NSObject subclasses or Core Data objects
2. Views being UIView and UIViewControllers that draw things on screen
3. Controller being application’s logic

Question 3

MVC: Avantages

Answer 3

1. Some architecture is better than none

2. It’s simple to understand and even novice developers can wrap head around

Question 4

MVC: Disadvantages

Answer 4

1. View controllers tend to be abused and given too much responsibility
2. Falls short in edge cases. Where do you put a service object that does HTTP networking?

Question 5

MVC: Alternatives

Answer 5

1. MVVM can help extract some business logic and data out of view controllers and into view models
2. SRP helps with setting firm boundaries for your code for object responsibilities

Question 6

What is MVVM?

Answer 6

1. A subset and extension of MVC
2. Adds View models that play an important role in data presentation and delegating business logic triggered by the view layer

Question 7

MVVM: Advantages

Answer 7

1. fits nicely into existing MVC architectures
2. more testable
3. state decoupling, responsibility decoupling

Question 8

What are the common layers of responsibility that an iOS application has?

Answer 8

UI Layer
Service Layer
Storage Layer
Business Logic Layer

Question 9

What is the UI Layer responsible for?

Answer 9

Display UI elements on the screen and take user input in and delegate to rest of your app

Question 10

What is the Service Layer responsible for?

Answer 10

All external communication your application has. ex: HTTP API client

Question 11

What is the Storage layer responsible for?

Answer 11

Ultimate source of truth for the application

Question 12

What is the Business Logic Layer?

Answer 12

Objects that use components and objects from other layers to achieve results and work for the user