[iOS] Swift Basic

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Code Structure

  • ViewController:

    • IBOutlet: control + click on element in storyboard and drop the mouse into viewController file, click connect
    • IBAction: control + click on the button and drag it to the code -> pops up action editing panel

  • Storyboard

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class ViewController: UIViewController {
    @IBOutlet weak var diceImageViewOne: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        diceImageView1.image = #imageLiteral(resourceName: "DiceOne")
    }

    @IBAction func rollButtonPressed(_ sender: UIButton) {
        diceImageViewOne.image = #imageLiteral(resourceName: "DiceFour")
    }
}
  • String
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var s = "some example string with \(variable)"
  • Range operator
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let randomNumber = Int.random(in: 1 ... 3) //  closed range [1, 3]
Int.random(in: 1 ..< 3) // half open range operator [1, 3)
Int.random(in: ...3) // one sided range [, 3] anything smaller than 3 including 3
Float.random(in: 1 ... 3) // float random
Bool.random()
array.randomElement()
array.shuffle()
  • Switch
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switch score {
    case 81...100:
        print("first range")
    case 41..<81:
        print("second range")
    case ...40:
        print("thrid range")
    default:
        print("Error")
}
  • Dictionary
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var dict : [String: Int] = ["Key": value]
  • Optionals
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var hardness: String? = nil
hardness = "something"
// unwrap optional
if hardness != nil {
    var unwrapped = hardness!
}
  • Timer
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var timer = Timer()

timer.invalidate() // reset timer
timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(updatedTimer), repeats: true)

@obj func updateTimer() { // obj: objective-c api exposed
    if secondsRemaining > 0 {
        secondsRemaining -= 1
    }
}
  • Float
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let a = 5
let b = 2

print(a / b) // 2

let a: Float = 5
let b: Float = 2

print(a / b) // 2.5
  • Struct

Struct name starts with a capital letter

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struct Town {
    let name = "Town name"
    var citizens = []
    var resources = ["Grain": 100, "Ore": 42, "Wool": 20]

    func fortify() {
        // do something
    }
}

var myTown = Town()
print(myTown.name)