Swift Basic 2

The arguments passed into the function can be simply passed in with an array dynamically

func sumOf(numbers: Int...) -> Int {
    var sum = 0
    for number in numbers {
        sum += number
    }
    return sum
}
sumOf()
sumOf(42, 597, 12)
sumOf(222,3333,44444,555555)

Functions can be nested using

func returnFifteen ()-> Int {
     var y = 10
     // nested function
     func add () {
         y + = 5
     }
     // reference nested functions
     add ()
     return y
}
returnFifteen ()

A function can return another function as its value

func makeIncrementer ()-> (Int-> Int) {
     func addOne (number: Int)-> Int {
         return 1 + number
     }
     return addOne
}
// return addOne (number: Int)-> Int {....} to increment
var increment = makeIncrementer ()
// Incoming parameters
increment (7)

A function can use another function as its passed-in parameter

func hasAnyMatches(list: [Int], condition: Int -> Bool) -> Bool {
    for item in list {
        if condition(item) {
            return true
        }
    }
    return false
}
func lessThanTen(number: Int) -> Bool {
    return number < 10
}
var numbers = [20, 19, 7, 12]
hasAnyMatches(numbers, lessThanTen)

You can write a closure without a name by surrounding code with braces ({}). Use with to separate the arguments and return type from the body.

var numbers = [20, 19, 7, 12]
// ---- multiply by 3 method one
numbers.map ({
     (number: Int)-> Int in
     let result = 3 * number
     return result
})
// ---- multiply by 3 method 2
let mappedNumbers = numbers.map ({number in 3 * number})
mappedNumbers
// ---- sort
let sortedNumbers = sorted (numbers) {$ 0> $ 1}
sortedNumbers

Objects and classes

 // class + class name
// {Property and method definition}
class Shape {
    var numberOfSides = 4
    let color = "# 3b5998"
    func simpleDescription ()-> String {
        return "A shape with \ (numberOfSides) sides."
    }
    func shadow (isShadowOn: Bool)-> String {
        if (isShadowOn) {
           return "This is ON"
        } else {
           return "This is OFF"
        }
    }
}

// first instantiate a class
// use class.propert class.method to refer to properties and methods
var shape = Shape ()
// rewrite property
shape.numberOfSides = 7
// call method
var shapeDescription = shape.simpleDescription ()
var shadow = shape.shadow (true)
// Define class Shape
class Shape {
    // define attributes
    let color = "# 000"
    var numberOfSides = 0
    var name: String
    //initialization
    init (name: String) {
        self.name = name
    }
    // define method
    func simpleDescription ()-> String {
        return "A shape with \ (numberOfSides) sides."
    }
}

// Create a new instance of Shape
var shape = Shape (name: "Test_Shape")
// Set properties
shape.numberOfSides = 7
// call method
var shapeDescription = shape.simpleDescription ()

// Subclass Square inherits from Shape
class Square: Shape {
    // Add attributes
    var sideLength: Double
    // Custom initialization method
    init (sideLength: Double, name: String) {
        self.sideLength = sideLength
        super.init (name: name)
        numberOfSides = 4
    }
    // added method
    func area ()-> Double {
        return sideLength * sideLength
    }
    // Rewrite parent method
    override func simpleDescription ()-> String {
        return "A square with sides of length \ (sideLength)."
    }
}
// Instantiate a Square
let test = Square (sideLength: 5.2, name: "my test square")
// call method
test.area ()
test.simpleDescription ()

Swift Basic 2