Good Swift Style and Conventions

TenSwiftStyleRules.swift

/*
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 Good Swift Style and Conventions
 
 March 2019 Austin iPhone Developer Meetup
 
 */



// 1. Delegate Protocol should be constrained to type of class
protocol SomeDelegate: class {
    func didTapCell()
}
weak var delegate: SomeDelegate?

// 2. Colon Spacing
var cost:Double = 2.00 // Bad.
var price : Double = 3.00 // Bad.
var profit: Double = 1.00 // Good!

// 3. Comma Spacing in functions
func sum(a:Int,b:Int) -> Int { // Bad.
    return a + b
}
func product(a: Int, b: Int) -> Int { // Good!
    return a * b
}

// 4. Control Statement Parentheses are Unnecessary
if (cost != 0) { // Bad.
    print("It's not free.")
}
if cost == 0 { // Good!
    print("It's free!")
}

// 5. Identifier Name
var num = 0 // Bad.
var theNumberOfTimesThatTheUserHasTappedOnTheLogInButton = 0 // Bad
var LoginTapCount = 0 // Bad.
var loginTapCount = 0 // Good!

// 6. Redundant Set Access Control Rule
internal(set) var youCanSetMe: Int // Bad.
public var doNotSetMe: Int // Good!

// 7. Trailing Comma
let oddNumbers = [1, 3, 5, 7, 9,] // Bad.
let evenNumbers = [0, 2, 4, 6, 8] // Good!

// 8. Duplicate Imports
import Foundation
import UIKit
import MapKit
import Foundation // Bad.
import HealthKit

// 9. For Where
for number in evenNumbers {
    if number > 0 {
        print(number) // Positive even number.
    }
}
for number in evenNumbers where number > 0 {
    print(number)
}

// 10. Don't Force Cast

class General {
    
}

class Specific: General {
    func run() { }
}

let object = Specific()
let specific = object as! Specific
specific.run()
print(String(describing: specific.self))

//let numberSquared = product(a: number, b: number) // Bad.
if let number = Int(exactly: 3.00) {
    let numberSquared = product(a: number, b: number) // Good!
    print(numberSquared)
}

func squareIfYouCan() {
    guard let number = Int(exactly: 3.14) else { return }
    let numberSquared = product(a: number, b: number) // Good!
    print(numberSquared)
}



// Automate this using SwiftLint https://github.com/realm/SwiftLint