Swift tips

SwiftTips.swift

// 1. - Iterate over items and indices in collections

var ingredients = ["potatoes", "cheese", "cream"]

for (i, ingredient) in ingredients.enumerated() {
    // The counter helps us display the sequence number, not the index
    print("ingredient number \(i + 1) is \(ingredient)")
}

// Array<String>.SubSequence
var doubleIngredients = ingredients.dropFirst()

for (i, ingredient) in zip(
    doubleIngredients.indices, doubleIngredients
) {
    // Correctly use the actual indices of the subsequence
    doubleIngredients[i] = "\(ingredient) x 2"
}

import Algorithms

for (i, ingredient) in doubleIngredients.indexed() {
    // Do something with the index
    doubleIngredients[i] = "\(ingredient) x 2"
}



// 2. - Label loop statements to control execution of nested loops

let matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

let valueToFind = 5
searchValue: for row in matrix {
    for num in row {
        if num == valueToFind {
            print("Value \(valueToFind) found!")
            break searchValue
        }
    }
}



// 3. - Overload the pattern matching operator for custom matching behavior

struct Circle {
    var radius: Double
}

func ~= (pattern: Double, value: Circle) -> Bool {
    return value.radius == pattern
}

let myCircle = Circle(radius: 5)

switch myCircle {
case 5:
    print("Circle with a radius of 5")
case 10:
    print("Circle with a radius of 10")
default:
    print("Circle with a different radius")
}

func ~= (pattern: ClosedRange<Double>, value: Circle) -> Bool {
    return pattern.contains(value.radius)
}

switch myCircle {
case 0:
    print("Radius is 0, it's a point!")
case 1...10:
    print("Small circle with a radius between 1 and 10")
default:
    print("Circle with a different radius")
}