Workshop Swift Structs, Enums and Classes: -Structs & Classes -Initialization -Access Levels & Extensions -Enums & associated values Presentado por los ingenieros Jordi Serra y Pierluigi Cifani

1. Swift: Structures
Jordi Serra – Pierluigi Cifani
iOS Workshops

2. Overview
- Structs & Classes
- Initialization
- Access Levels & Extensions
- Enums & associated values

3. Structs and Classes

4. Structs and Classes
Structs and Classes are the main structures in Swift
Basic syntax:

5. Comparing Classes and Structs
Both can:
- Define properties & methods
- Define initializers to set up their initial state
- Be extended through extension syntax
- Conform to protocols
Classes have additional capabilities:
- Inheritance
- Type casting
- Deinitializer
- More than one reference to a class instance

6. Comparing Classes and Structs
Structs are passed by value, Classes are by reference
- Structs are non mutating by default
- Structs are copied whenever passed into a function
(optimization with copy on write)
When to use struct over class:
- Encapsulates few data types
- It can be copied around (no struct singletons)
- Values inside are structs themselves
- It does not need to inherit behavior
Struct examples: Vector, Points, any Models and ViewModel

7. Initialization & Properties

8. Initialization
Special function with init
keyword
- Accepts params, never
returns
- All non-optional values
must be set in initializer
- The compiler sets
default initializer if all
props have default
values
- Can be failable: init?()
- And a lot more

9. Properties
Properties in structs and classes hold values than can change
or not over time.
Declared using either var or let

10. Singleton
Singletons in swift are very straightforward

11. Getters and Setters
Properties can have its own get & set functions
.. and property observers

12. Access types & extensions

13. Access Types (I)
Access Levels (from less to more restrictive)
open, public, internal, fileprivate and private
Open:
Enables usage, inheritance and override functionality from
anywhere in the module and any other module that imports
it
Public:
Enables usage, from anywhere in/out the module, enables
inheritance and override from the same module only.

14. Access Types (II)
Internal:
Enables usage from anywhere inside the module, but not
outside the module
Fileprivate:
Restricts the use of an entity to its own defining source file
Private:
Restricts the use of an entity to the enclosing declaration

15. Extensions
Used to add new functionality to classes and structs
Extensions in Swift can:
- Add computed instance properties and computed type
properties
- Define instance methods and type methods
- Provide new initializers
- Define and use new nested types
- Make an existing type conform to a protocol
- Provide default protocol implementations
Extensions allow extending types for which you do not have
access to the original source code

16. Extensions Syntax
Computed Property

17. Extensions Syntax
Initializers
Methods

18. Mutating Functions
Structs are always passed as values. Therefore, it can never
be changed inside a function (they are always a copy)
To mutate a struct, use mutating keyword

19. Enums & associated values

20. Enums
Declaration Usage

21. Enums
Enums can be extended the same way as any other struct

22. Raw Values
Enum declaration can extend a raw value type. Then, it has
rawValue property available

23. Associated Values
Enum cases can have a type associated. This should be
initialized whenever the enum is.

24. Associated Values (II)
The associated values can be taken inside the switch
statement, as a let or var parameter