Swift

4 layers: From the user to the device

• Cocoa Touch
  • Multitouch, Alerts, core motion, View hierarchy, Localisation, Controls, Image Picker, Camera, Map Kit, Web View, Alerts
• Media
  • Core Audio, Open AL, Audio mixing etc, Video Playback etc. animations, 3d etc. Photos
• Core Services
  • Object-Oriented layer of acessing the Core OS layer
  • Collections, Networking, file access, SQLite, URL, Preferences, Threading, Net services, Location, Address book
• Core OS
  • OSX Kernel, power managerment, keychain, Bonjour, Security, Sockets, FS, BSD , Mach 3
  • In C programming language

In Swift frameworks are collections of objects (UIKit, Map Kit etc.)

Design strategy -> MVC

You can mix Swift and Obj-c as much as you wish, they are interoperable, even in the scope of one App.

Info.plist needs to be in the root level of the project (for easiness).

UI is build in XCode graphically. By dragging and dropping. In .storyboard files.

Interface Builder.

• alt + mouse wheel => Zoom

Document Outline.

Two circles button -> Assistant Editor (storyboard + kod do storyboardu). Outlet-> ? Action -> Method. When the button is pressed (action), call a method.

• Argument: Sender argument (?)
• Type: UIButtont !!!! ⚠️

Use CTRL to drag the button to the code (creating an action)

names if the parameters ​

Plural.

@IBAction touchCard(_ sender: UIButton) -> Int {}

• Every argument has a name that you include when yoiu call the method
• It has two names. External name that the caller uses and the inside name that we use inside the implementation
• there are some good practices to learn yet.

Single names are alowed (same name for the caller and for the implemetation). _ - no argument. But we almost never do it. It's back from Objective-C

XCode Behaviors ​

• automation of showing the debugger and else. Worth investigation.

UIControlState - what's that? Hold down Option and mouse, click on thing and the docs will be there. Noise.

Always read the Overview part in the docs.

Color literal => color picker in XCode XD CO ZA DZBANERIA

\(string) ​

Copy -paste in intefrace builder copies and pastes the actions/outlets. Right-click in Interface Builder allows to disconnect the outlets.

Instance variable? -- class field? ​

Or properties. var name: Type

The instance variables need to have value or be initialised in _initialiser.

Swift is extremely typed language. It has type for "unknown" but for the sake of maintaining compatibility.

It also has a strong types inference. It'll guess stuff. By clicking option and variable we can see what type Swift thinks the variable is. Most of the time, you'll be using typing in function arguments.

Every time you're copying and pasting the code - you're doing it wrong.

@IBOutlet -> instance variable/property @IBAction -> method Outlet collection -> array of buttons/ui elements 😄

! doesn't be initialised (or weak), I don't know yet.

Property observer

Cmd+click -> Quick actions (rename variable itp.)

You can also drag from the View COntroller icon to the UI element to connect an element to an action/outlet/colloection of outlets.

let is constant in Swift // let variable equal 1var is variable

Triangle fixes the errors in the code. Simple as that.

Optional ​

Int?, means that the Optional Int is an entirely different type than Int in Swift. In returned value it means the function may return something.

Optional has only two states: set or not set. For each case in an enumeration you can have associated data. Set state means the Int is associated. Not set is nil.

nil => not set value of an Optional. Putting the ! means: assume the value is set and forcefully try to get the value (unwrap the value). May cause crashes.

You can do such construct to unwrap:

if let cardNumber = cardButtons.index(of: sender) {
	// ...cardNumber
} else {
	// print...
}

Property observer ​

Any property can be observed and call didSet {} fn once the property has been changed

var flipCount = 0 {
	didSet {
		flipCountLabel.text = "Flips: \(flipCount)"
	}
}

didSet is observing changes of flipCount. Noice.

Resources ​

• Developing iOS Apps with Swift