Swift Tour Essay summary (1)

Let Constant

var Variable

let implicitInteger = 70
let implicitDouble = 70.0
let explicitDouble: Double = 70

The so-called type implications

To include the value in strings:

let fruitSummary = "I have \(apples + oranges) pieces of fruit."

Arrays and Dicts:

var shoppingList = ["catfish", "water", "tulips"]
shoppingList[1] = "bottle of water"
var occupations = [
    "Malcolm": "Captain",
    "Kaylee": "Mechanic",
]
occupations["Jayne"] = "Public Relations"
//empty
let emptyArray = String[]()
let emptyDictionary = Dictionary()

Control Flow and Optional Binding

For each

let individualScores = [75, 43 103, 87, 12]
var teamScore = 0
for score in individualScores {
    if score > 50 {
        teamScore += 3
    } else {
        teamScore += 1
    }
}
teamScore

Optional Binding

var optionalString: String? = "Hello"
optionalString == nil

var optionalName:String? = "John Appleseed"
var greeting = "Hello!"

//optional binding
if let name = optionalName {
    greeting = "Hello, \(name)"
}

If The optional valuenilis, the conditional are and thefalsecode in braces are skipped.

Otherwise, the optional value is unwrapped and assigned to the constant afterlet, which makes the unwrapped value avail Able inside the block of code.

Swift Tour Essay summary (1)