gist to learn Swift

hello-swift

// Playground - noun: a place where people can play

import UIKit

var str = "Hello, playground"

// array
var a1 = [1, 2]
var a2 = [3, 4]
var a3 = a1 + a2

var b1 = [1.5, 2.5]
b1 += [2.4]

// dictionary
var d3 = ["Apple": 1, "Orange": 2]
println(d3["Apple"])
d3 = [:]

// tuple
var t2 = (index: 1, value: "hello")
let (index, value) = t2
println("index: \(index), value: \(value)")

// demo of closure
func square(a: Float) -> Float {
    return a * a
}

func cube(a: Float) -> Float {
    return a * a * a
}

func averageOfFunction(a: Float, b: Float, f: (Float -> Float)) -> Float {
    return (f(a) + f(b)) / 2
}

println("\(square(2)), \(square(4)), \(averageOfFunction(2, 4, square))")

// demo of array map, filter, reduce functions
var a4 = a3.map({$0 + 1}) // add 1 to each element in a3
var a5 = a3.filter({$0 > 3}) // filter out elements smaller than 4 in a3
var a6 = a3.reduce(0, {$0 + $1}) // use reduce to add up elements in a3
var a7 = a3.reduce(0, +) // use reduce to add up elements in a3

println("a3: \(a3), a4: \(a4), a5: \(a5), a6: \(a6), a7: \(a7)")

var s = "hello, world"
for scalar in s.unicodeScalars {
    println(scalar)
}


func sayHi(greeting: String, #name: String) {
    println("\(greeting), \(name)")
}
sayHi("hi", name: "Jobs")

func sayHi(greeting: String = "hello, world") {
    println(greeting)
}
sayHi()
sayHi(greeting: "hi, earth")

var optionalVal: Int?
optionalVal = 1
if let optionalVal = optionalVal {
    println("optionalVal: \(optionalVal)")
}
var optionalValue: Int? = 1
if let optionalValue = optionalValue {
    println("The int was \(optionalValue)")
} else {
    println("The int was not there.")
}