Niki27gupta

var stepCount: Int = 0 {
    willSet(newSteps) {
        print("About to update steps to \(newSteps)")
    }
    didSet {
        if stepCount > oldValue {
            print("Added \(stepCount - oldValue) steps")
        }
    }
}

Niki27gupta

struct Square {
    var sideLength: Double // Stored Property
    
    var area: Double { // Computed Property
        get {
            return sideLength * sideLength
        }
        set(newArea) {
            sideLength = sqrt(newArea)
        }

Niki27gupta

let temperature = 35

switch temperature {
case let t where t >= 100:
    print("Boiling!")
case let t where t <= 0:
    print("Freezing!")
default:
    print("Liquid state")
}

Niki27gupta

let point = (2, 0)

switch point {
case (0, 0):
    print("At the origin")
case (let x, 0):
    print("On the x-axis at \(x)") // Binds the value of '2' to x
case (0, _):
    print("On the y-axis") // Ignores the y value
default:

Niki27gupta

func processOrder(id: Int?) {
    guard let orderId = id else {
        print("Error: No ID provided.")
        return // Must exit scope
    }
    
    // orderId is available for the rest of the function!
    print("Processing order #\(orderId)")
}

Niki27gupta

func showProfile(name: String?) {
    if let unwrappedName = name {
        print("Hello, \(unwrappedName)")
        // unwrappedName is only accessible here
    }
    print("This line runs whether name was nil or not.")
}

Niki27gupta

let displayedName = userName ?? "Anonymous"

Niki27gupta

var userName: String? = nil
var displayedName: String

if let name = userName {
    displayedName = name
} else {
    displayedName = "Anonymous"
}

Niki27gupta

func swapValues<T>(_ a: inout T, _ b: inout T) {
    let temporaryA = a
    a = b
    b = temporaryA
}

Niki27gupta

let response = (404, "Not Found") // Inferred as (Int, String)