IOS development with Swift

1 Basics

IOS layers:

Cocoa Touch
- Web View, Controls, Camera, Image Picker, etc
Media
- Audio, JPEG, etc
Core Services
- Collections, Networking, File, Threading, etc
Core OS
- OSX Kernel

Demo

Edit UI in storyboard.
Connect UI and controller functions or variables by hold Control and drag.
- Connection can be
  - Action: a function
  - Outlet: a special var of a thing in UI
  - Outlet collection: an array var of UI things
    - Use yellow View Controller to add into the array.
Right click on UI component to check connections.
Hold Option and click function names to check document.
Command click connection var to jump to def or refactor.
Get real value from optional: let n = arr.index(of: x)!
- better: if let n = arr.index(of: x) {}

class ViewController: UIViewController // inheritance
{
    var count : Int = 0  { // instance var 
        didSet {
            // to be executed when set this var
            flipCountLabel.text = "Flips: \(count)" // embed variables in string
        }
    }

    var num = 2.0 // works too

    // Each argument has two name: external and internal; can be only one
    func flipCard(withEmoji emoji: String, on button: UIButton) {
        // ...
    }
}

2 MVC

A single MVC can only manage at most a single screen.

Model is what the application is; UI independent.
Controller: interpret/format model info for the view.
- Controllers are almost always the data source.
- View action to controller target.
- Delegation: should, will, did.
- Data source
View: generic UI components.
Controller can talk to model.
Model can use Notification & KVO to broadcast changes to Controller.
Controller can outlet to view.
View to controller
- View action to controller target.
- Delegation: should, will, did.
- Data source

Create a class: File -> New -> File -> Swift File

class
- Reference type
- Initializer is needed when we have uninitialized vars.
struct
- Value type, get copied when assigned or passed
- No inheritance
- Include free initializer

// class
class Concentration 
{
    var cards = Array<Card>() // init; or [Card]()

    func chooseCard(at index: Int) {

    }

    init(numCards: Int) {
        for id in 0..<numCards { // ..< means not including, ... means including
            let card = Card(id: id)
            cards.append(card)
            cards.append(card) // copied
            // or
            cards += [card, card]
        }
    }
}

// struct
struct Card
{
    var isFaceUp = false
    var isMatched = false
    var id: Int
    static var idFactory = 0
    static func getUniqId() -> Int {
        Card.idFactory += 1
        return Card.idFactory
    }
    init() {
        self.id = getUniqId()
    }
}

// in ViewController
class ViewController: UIViewController 
{
    // lazy allows init this var only when using it
    // no didSet() for lazy
    lazy var game = Concentration() // create a model

    var emoji = Dictionary<Int, String>() // dict
    // or
    var emoji = [Int: String]()

    func updateViewFromModel() {
        for index in cardButtons.indices {
            // ...
        }
    }

    func emoji(for card: Card) -> String {
        if emoji[card.id] == nil {
            let randInd = Int(arc4random_uniform(UInt32(emojiFactory.count)))
            emoji[card.id] = emojiFactory.remove(at: randInd)
        }
        return emoji[card.id] ?? "?"
    }
}

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IOS development with Swift

1 Basics

Demo

2 MVC