Teaching programming to Daniela using Swift

LessonOne.playground

// Learning Swift with Daniela #1

/* 
 *  Lesson Plan
 *  ===========
 1. Variables & Constants
 2. Types
 3. Operators
 4. Condtionals & Branching
 */

// Print a String to the console
println("Hello, world!")

// A String is a string (or sequence) of characters (letters) denoted by quotation marks

// This is a constant. It cannot be changed.
// It is useful for referring to a value multiple times.
let constantHello = "Hello" // "String"

println(constantHello)
println(constantHello)

// This is a variable.
// It is like a constant, but it can be altered.
var changeableHello = "Hello is changable"

println(changeableHello)

changeableHello = "Hello, Daniela!"
println(changeableHello)

// You can declare multiple variables/constants on one line by separating them with commas.
var pi = 3.14, tau = 2.28

// Swift's *type inference* lets it figure out what type of data is written
var x = 5 // int (Integer)

// Type Annotation!
// This lets us declare a variable or constant's type explicitly.
// In Java: String myString = "Uh..."

// Type annotation in Swift
var myString: String = "Uh..."
var myInteger: Int = 5
var myFloat: Float = 5.1
var myBoolean: Bool = true

// Basic Types:
// String -> sequence of Characters
// Character -> letter
// Int -> whole number
// Float -> floating-point number (decimal)
// Double -> float with higher precision
// Boolean -> true or false

let sum = 1 + 1
let decimalSum = 1.0 + 1.0


// "camelCase" makes identifies more legible
// writeABunchOfWords <- Easier to read
// writeabunchofwords

let daniela = "Daniela"
let ronald = "Ronald"

let smushedName = daniela + ronald

// Binary operators take two arguments
println(daniela + ronald)
println(2 * 3)
4 / 2
1 - 1
2 % 2

// Unary (one argument) operator
// negative sign (-) is the unary operator
var negativeOne = -1
var positiveOne = -negativeOne

let isDoneWithService = true

// Ternary operator takes three arguments
// Format:
// condition ? valueIfConditionIsTrue : valueIfConditionIsFalse
var danielaStatus = isDoneWithService ? "I'm done!" : "I'm not done yet."

// The above has the same meaning as:
if isDoneWithService {
    danielaStatus = "I'm done"
} else {
    danielaStatus = "I'm not done yet."
}