Swift

Introduction

Here is my first dip into Apple and swift Swift Cheat Sheet

Data Types

Here we have the following Primatives

• Int
• Float
• Double
• Str
• Bool

Control

If Statements

No surprises

if a < 4 {
  print("we are here 1")
}
else if a == 4 && a < 3 {
  print("we are here 2")
}
else {
  print("we are here 3")
}

Switch Statements

var aCharacter = "a"
switch aCharacter {
   case "a":
      print("we are here a")
   case "b":
      print("we are here b")
   default:
      print("we are here not a or b")
}

Loops

Example for loop

var sum = 0
for index in 1..5 {
   sum += index 
   print(sum)
}

Example for while loop

var counter = 5
while counter  > 0 {
   print("hello")
   counter -= 1  
}

Example for repeat while loop

var counter = 5
repeat {
   print("hello")
   counter -= 1  
} while counter  > 0

Functions

Simple example

func foo() {
  print("Fred")
}
foo()

The argument label, the first argument, is just a name to use in place or variable name

func addTwoNumbers(
  arg1 para1:Int,
  arg2 para2:Int) -> Int {
  return para1 + para2
}
let sum = addTwoNumbers(arg: 2)
print(sum)

Classes

Base Claas

class BlogPost {
  var title = ""
  var body = ""
  var counter = 0
  func addCounter() {
    counter += 1 
  }
}

let myPost = BlogPost()
myPost.title = "Hello"
myPost.body = "My Body"
myPost.addCounter()
print(myPost.counter)

Optional Properties

We can make properties optional. Like most languages we need to test

class BlogPost {
  var title:String?
  var body = "hey"
  var counter = 0
}
let post = BlogPost()

// We test like this.
if let actualTitle = post.title {
   print(actualTitle)
}

Initialise (Constructor)

We use self in place of this for other languages. Don't forget about argument labels. Note more than one init() permitted

class Person {
  var name = ""
  var age = 0

  func init(_ name: String) {
    self.name = name
    self.age = 22
  }

  func init(_ name: String, _ age: Init) {
    self.name = name
    self.age = age
  }
}
var a Person("Bill", 21)

Inheritance

We do this using a colon

class ImprovedBlog : BlogPost {
  var title = ""
  var body = ""
  var numberOfLikes = 0
  func addNumberOfLikes() {
    numberOfLikes += 1 
  }
}

Override can be used and you can call the base implementation

class NewCar : Car {
  override func drive() {
    print("Printing my stuff")
    // Print base stuff 
    super.drive()
  }
}