Mobile Applications Development. Swift, Cocoa and Xcode

Transcription

1 Mobile Applications Development Swift, Cocoa and Xcode

2 Swift programming language Swift is the programming language for ios, macos, watchos, and tvos app development First version in 2014 Current version is 3.0, integrated whitin XCode 8.0 (and Ubuntu) Multi-paradigm (object, functional, imperative) Open-source (Apache 2.0 License) Use Clang - LLVM compiler (open-source, cross-platform) Modern language: inferred typing, playground, scripting (REPL), safety, Easy memory management with Automatic Reference Counting (ARC)

3 Swift language must be verbose Variables, identifiers, functions, constants Use camelcase to make it easier to read identifiers with multiple words, every word after the first word should be capitalized. Readability brings semantic Good names clearly describe what they represent Easier to read, easier to understand

4 Constants and Variables Constants are immutable, variables are mutable For memory optimization and safety // Declaring a constant let placeofbirth = "Grenoble" // Declaring a variable var currentlocation = "Hanoï"

5 Types and variables In Swift, no need to specify variable s type The first time you assign a value to a variable, the variable s type automatically becomes the type of the value Type annotation can be inferred let annotateddouble: Double = 20 let inferreddouble = 0.5 A lot of types Named types: Classes, Structures, Enumerations, Protocols Data types (primitives): Int, Float, String, Compound types: Tuples, Array, Dictionnary, swift types...

6 Optional Types and variables Variables can be empty: the nil value Safety in Swift force to declare variables as optional or not var canbenil : String? = "hello" canbenil = nil var cannotbenil : String = "hello" cannotbenil = nil // error: don t compile To get the value from an optional variable, we need to unwrap it print(canbenil!) // prints "hello" print(canbenil) // prints Optional("hello") Calling a method (or a variable) to an optional, must be done safety canbenil?.append(" world") // stops after? if canbenil is nil

7 Optional Types and variables Optionals can be declared to automatically unwrap, but beware! var canbenil : String! = "hello" var canbenil : String! = nil print(canbenil) // no unwrapping needed: prints "hello" print(canbenil) // error! Need optional binding Optional binding if let canbenilsafe = canbenil { print(canbenilsafe) Optional chaining if let johnsstreet = john.residence?.address?.street { print("john's street name is \(johnsstreet).") else { print("unable to retrieve the address.") «if the optional variable canbenil is not nil, set a new constant called canbenilsafe to the value contained in the optional.»

8 Collection types: Tuple, Array, Dictionary Range let underfive = 0.0..<5.0 print(underfive.contains(3.14)) // Prints "true» print(underfive.contains(6.28)) // Prints "false» print(underfive.contains(5.0)) // Prints "false" Tuple var sometuple = ("John", "Smith") var somenamedtuple = (firstname: "John", lastname: "Smith") Array var somearray = ["catfish", "blue water", "tulips", "blue paint"] for name in somearray where name.hasprefix("blue") { print(name) somearray[1...3] = ["1","2","3"] //slicing with closed range somearray[1..<3] = ["1","2"] //slicing with half-open range var emptyarray = [String]() emptyarray.append("hello") Dictionary var occupations = ["Malcolm": "Captain", "Kaylee": "Mechanic"] occupations["jayne"] = "Public Relations var emptydictionary = [String: Float]()

9 Types: Strings Strings are encoded with Unicode, as any identifier in Swift let firstname = "Stephane" let = "Hanoi" var welcomestring = "Hello " + firstname + ", welcome to " + + "!» welcomestring = "Hello \(firstname), welcome to \( )!» Some useful properties, subscripts and functions for character in "Dog! ".characters { // for-in loop print(character) firstname.characters.count // returns 8 firstname.hasprefix("ste") // returns true let hellostring = "Yo, Hello world!" let startindex = hellostring.index(hellostring.startindex, offsetby: 4) let endindex = hellostring.index(hellostring.endindex, offsetby:-7) let substring = hellostring.substring(with: startindex..<endindex) // returns "hello"

10 Swift functions Syntax is very flexible allows simple C-style to complex Obj-C-style The function s name is supposed to describe what it does func greet(name: String) -> String { let greeting = "Hello, " + name + "!" return greeting Function called greet(name:), takes a name as a String argument and returns a String Named parameters, variadic parameters, inout parameters

11 Swift functions: Argument labels By default, parameters must be named, ie: must be called with param name à greet(name:"stephane") An argument label can be added for more readability func greet(person name: String) -> String { let greeting = "Hello, " + name + "!" return greeting à greet(person:"stephane") Add _ before name in function declaration to allow unamed params func greet(_ name: String) -> String { let greeting = "Hello, " + name + "!" return greeting à greet("stephane")

12 Swift functions: inout parameters Like in C, parameters can be modified when pointer is passed Use keyword inout instead of * on declaration Use & in function call func swaptwoints(_ a: inout Int, _ b: inout Int) { let temporarya = a a = b b = temporarya var someint = 3 var anotherint = 107 swaptwoints(&someint, &anotherint)

13 Swift: Closures Self-contained blocks similar to blocks in C (and Objective-C) or lambdas in other languages. Can be used as a function or passed as an argument of a function General syntax { (parameters) -> return type in //statements

14 Swift closures Consider the function: func backward(_ s1: String, _ s2: String) -> Bool { return s1 > s2 A call to this function as a function s argument var reversednames = names.sorted(by: backward) A call to this function as a closure var reversednames = names.sorted(by: { (s1: String, s2: String) -> Bool in return s1 > s2 ) Types can be inferred, return can be implicit, for simpler syntax var reversednames = names.sorted(by: { s1, s2 in s1 > s2 )

15 Swift trailing closures When a closure is passed as a final argument, there are trailing closures Consider the function: Call this function without using a trailing closure Call this function with a simpler trailing closure instead (no argument label)

16 Swift: Classes and Structures Both are almost the same in Swift Contain properties to store values Contain methods to providefunctionality Have initializers to set up their initial state Most notable difference : Structures are Value Type, Classes are Reference Type

17 Swift: Structures Structures have a default initializer, with parameter for each property «Value Type» à a structure is copied when assigned to a variable or passed to a function Any properties stored by the structure are themselves value type Defining a structure type gets to choose which properties can possibly be changed, using the type can decide whether a particular instance is mutable or not struct Song { let title: String let artist: String var rating: Int var song = Song(title: "Breathe", artist: "Pink Floyd", rating: 0) song.rating = 4 let song = Song(title: "Breathe", artist: "Pink Floyd", rating: 0) song.rating = 4

18 Swift: Classes Classes are «Reference Type», copied by reference Identity operator === or!== to check whether variables refer to the same instance (or not) Type check operator is to check for type s ownership Classes memory is managed by ARC (no garbage collector) à class s instance need more resources than structure s instance A class inheritates one single class and can implements multiple protocols (interfaces)

19 Classes and Structures syntax All in one file, not separated implementation and interface files struct Resolution { var width = 0 var height = 0 class VideoMode { var resolution = Resolution() var interlaced = false var framerate = 0.0 var name: String? var someresolution = Resolution() someresolution.width = 100 var anotherresolution = someresolution anotherresolution.width = 200 print(anotherresolution.width, someresolution.width) // prints var somevideomode = VideoMode() somevideomode.framerate = 25.0 var anothervideomode = somevideomode anothervideomode.framerate = 30.0 print(somevideomode.framerate, anothervideomode.framerate) // prints Structures are used for (simple) data encapsulation, where reference is not necessary

20 Classes and Structures initializers Similar to class constructor in any object-oriented languages Prepare a new instance before its first use It s not a function à don t use func keyword, but init() Allow various initializers, using Arguments Labels, or different list of parameters class Celsius { var temperatureincelsius: Double init(fromfahrenheit fahrenheit: Double) { temperatureincelsius = (fahrenheit ) / 1.8 init(fromkelvin kelvin: Double) { temperatureincelsius = kelvin init(_ celsius: Double) { temperatureincelsius = celsius let boilingpointofwater = Celsius(fromFahrenheit: 212.0) // boilingpointofwater.temperatureincelsius is let freezingpointofwater = Celsius(fromKelvin: ) // freezingpointofwater.temperatureincelsius is 0.0 let bodytemperature = Celsius(37.0) // bodytemperature.temperatureincelsius is 37.0

21 Classes and Structures initializers struct Color { let red, green, blue: Double init(red: Double, green: Double, blue: Double) { self.red = red self.green = green self.blue = blue init(white: Double) { red = white green = white blue = white let magenta = Color(red: 1.0, green: 0.0, blue: 1.0) let halfgray = Color(white: 0.5)

22 Classes and Structures properties A property is a general class or structure member, but Swift allows for more fun behaviour: Computed property do not store any value, it is computed when needed Property observers allow to trigger an action when a property s value changes willset is called just before the value is stored. didset is called immediately after the new value is stored. In classes, any properties must be initialized or declared as optional

23 Classes and Structures : computed property struct Point { var x = 0.0 var y = 0.0 struct Size { var width = 0.0 var height = 0.0 struct Rect { var origin = Point() var size = Size() var center: Point { get { let centerx = origin.x + (size.width / 2) let centery = origin.y + (size.height / 2) return Point(x: centerx, y: centery) set { origin.x = newvalue.x - (size.width / 2) origin.y = newvalue.y - (size.height / 2)

24 Classes and Structures : property observers class StepCounter { var totalsteps: Int = 0 { willset { print("about to set totalsteps to \(newvalue)") didset { if totalsteps > oldvalue { print("added \(totalsteps - oldvalue) steps") let stepcounter = StepCounter() stepcounter.totalsteps = 200 // prints "About to set totalsteps to 200" // prints "Added 200 steps" stepcounter.totalsteps = 360 // prints "About to set totalsteps to 360" // prints "Added 160 steps" Similarily to computed properties, use shortcuts newvalue and oldvalue

25 Classes and Structures methods Both classes and structures can define functions (methods) Methods belong either to instances or types (class, static methods) Methods are verbose, they use Argument Labels class Counter { var count = 0 func increment() { count += 1 func increment(by amount: Int) { count += amount instance variable instance method instance method, called increment(by:) func reset() { count = 0

26 Classes and Structures methods Structure s functions consider self immutable, add mutating to make it mutable struct Spaceship { var name: String mutating func setname(_ newname: String) { name = newname var enterprise = Spaceship(name:"Enterprise") enterprise.setname("enterprise A")

27 class Counter { var count = 0 static var counters = [Counter]() init() { Counter.counters.append(self) func increment() { count += 1 func increment(by amount: Int) { count += amount func reset() { count = 0 static func resetall() { for counter in counters { counter.reset() var firstcounter = Counter() firstcounter.increment(by: 10) print(firstcounter.count) // prints 10 var secondcounter = Counter() secondcounter.increment(by: 20) print(secondcounter.count) // prints 20 Counter.resetAll() print(firstcounter.count, secondcounter.count) // prints 0 0

28 Classes inheritence Swift allows for single inheritence only Accessing Superclass Methods, Properties, and Subscripts using super prefix Overriding methods, properties (stored, calculated, observers) using override prefix class SomeSubclass: SomeSuperclass { // subclass definition goes here class Train: Vehicle { override func makenoise() { print("choo Choo")

29 Swift: Protocols Similar to Java interfaces: specifying requirements that conforming types must implement a protocol can then be adopted by a class or structure to provide an actual implementation of those requirements Also used for (kind-of) multi-inheritence a class or structure can conform to multiple protocols class SomeClass: SomeSuperclass, FirstProtocol, AnotherProtocol Checking for protocol conformance with operator as for object in objects { if let objectwitharea = object as? HasArea { else { print("area is \(objectwitharea.area)") print("something that doesn't have an area")

30 Swift: Automatic Reference Counting (ARC) Simplify and optimize memory management of Classes Types whenever you assign a class instance to a property, constant, or variable, that property, constant, or variable makes a strong reference to the instance count how many strong references are currently assigned, release instance when the counter is equal to zero Just works most of the time Sometime need to manage Strong Reference Cycles à weak or unowned references

31 Swift: and many more Subscripts: define shortcuts for accessing the member elements of a collection, list, or sequence Ø html Error Handling: it s easy to throw errors Ø ing.html Extensions: add new functionality to an existing type (even without source code) Ø Generics: write flexible, reusable functions and types that can work with any type Ø tml

32 Write Swift with Xcode

33 XCode

34 Xcode Project structure At the Navigator panel, two type of files:.swift à files that include code (in swift!) : classes, controllers,.storyboard à where to design interfaces, and workflow between views Assets.xcassets organise images and icons in various resolution Access project s setting panel from the top blue icon

35 Xcode - Navigation Navigator (project s files) Console Show and hide navigator and utilities areas Switch Standard / Assistant / Version editor Show various information in the navigator and areas Utilities area Convenient for IBOutlets and IBActions connection Utilities area (right panel) has contextual menu fromthe Storyboard UI objects settings IBOutlets and IBAction UI objects library

36 Xcode - Storyboard Design views with Interface Builder Control the most used UIObject variables Not any Core Animation properties: layer, animation Manage multi-resolutions devices: constraints and traits Add workflow, interaction, gestures, and much more Almost full application can be design from Storyboard Don t generate any code in.swift files Need to «bind» variables (IBOutlet) and functions (IBAction) Segues to pass information between ViewControllers Ø Optional (and convenient) tool, but everything can be done in.swift only

37 Xcode - Storyboard UIViewControllers Entry point Segues UIViews

38 Xcode IBOutlets Connect UIObjects from Storyboard to Swift variables No code is generated: when storyboard is loaded, UIObjects are automatically instanciated Use IBOutlets if any interaction from code is needed Full circle means IBOutlet isconnected Prefix var will make variable visible in Storyboard Must be optional! Use assistant editor s view for convenient connection Or from Storyboard: right-clic from ViewController s icon to UIObject

39 Xcode IBActions Connect UIObjects from Storyboard to Swift functions From Storyboard: right-clic from UIObject to ViewController s icon (or use Assistant editor) Full circle means IBAction is connected sender is a reference to UIObject that sent an action (optional argument) Type casting an optional variable Get UIObject by tag can replace IBOutlets, but more dirty be careful!

40 Develop an ios application

41 Start: Application overview Xcode manages itself the main function, don t touch it! It instanciates UIApplicationMain with necessary arguments according to the project s settings UIApplicationMain first loads the default Storyboard file Then the run loop starts A UIApplication follows MVC model and Delegation design pattern

42 UIApplication the key parts The Model part could include any kind of data (images, text files, databases) depending of the app.. The UIApplication object manages the event loop and other high-level app behaviors: app states, memory warning, push notifications,... UIWindow manage the presentation of the app. Usually one window only. App Delegate is the heart of the code. It implements UIApplicationDelegate to interact with UIApplication ViewController objects manage the presentation of your app scontent on screen. A view controller manages a single view and its collection of subviews. UI Objects provide the visual representation of the app s content.

43 UIApplication Events in the main Run Loop Most of ios events belongs Touches, Motions, Accelerometer, Gyroscope, Location, Drawing, Are usually delivered using the main run loop to The delegate controller A block (or closure code)

44 UIApplication Life cycle The system automatically move the app from a state to another Received a phone call Home button pushed Memory issue Most state transitions are delivered to the UIApplicationDelegate : the «AppDelegate»

45 UIApplicationDelegate Life cycle optional public func applicationdidfinishlaunching(_ application: UIApplication) optional public func application(_ application: UIApplication, didfinishlaunchingwithoptions launchoptions: [UIApplicationLaunchOptionsKey : Any]? = nil) -> Bool optional public func applicationdidbecomeactive(_ application: UIApplication) optional public func applicationwillresignactive(_ application: UIApplication) optional public func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey = [:]) -> Bool // no equiv. notification. return NO if the application can't open for some reason : Any] optional public func applicationdidreceivememorywarning(_ application: UIApplication) // try to clean up as much memory as possible. next step is to terminate app optional public func applicationwillterminate(_ application: UIApplication) optional public func applicationsignificanttimechange(_ application: UIApplication) // midnight, carrier time update, daylight savings time change optional public func application(_ application: UIApplication, didchangestatusbarframe oldstatusbarframe: CGRect)

46 UIKit A quick tour on UIObjects

47 UIKit UIView UIViewController All UIObjects inheritate UIView properties and functions UIViews coordinate units is Point (contains multiple pixels accordingto the resolution) Some properties are animable: frame, center, transform, alpha, backgroundcolor UIObjects need a Core Animation layer for advanced design settings cornerradius, shadowoffset, bordercolor, MVC design: a view has a controller UIViewController is a base ViewController Responsible to the View s life cycle Ø A «Single View app» template contains one unique UIViewController

48 UIKit A quick tour Create a UIView without Storyboard let greensquareview = UIView(frame: CGRect(x: 100, y: 100, width: 100, height: 100)) greensquareview.backgroundcolor = UIColor.green greensquareview.layer.cornerradius = 25 greensquareview.layer.borderwidth = 2 self.view.addsubview(greensquareview) self is a ViewController self.view is its default view. We could also replace it, but the view is then resized to the full window screen

49 UIKit A quick tour Create a UIView with Storyboard 1. Drag & drop a UIView object 2. Configure itfromthe Utilities area 3. If needed, connect it with a IBOutlet variable

50 UIKit Segues Designed at Storyboard to control app workflows Transition between ViewControllers Similar but different to Android s Intents Define Segue s identifier and properties Properties depends of used Controller If needed, override the dedicated function override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if (segue.identifier == "ShowSecondVC") { segue.destination.view.backgroundcolor = UIColor.red

51 UIKit Delegation design pattern «One object in a program acts on behalf of, or in coordination with, another object.» In Cocoa, the delegating object is typically a framework object, and the delegateis typically a custom controller object. Ø Many UIObjects use Delegation design pattern to interact with its controller Ø The controller must conforms a dedicated protocol, usually called UIObjectDelegate

52 UIKit A simple delegation example UITextField must communicate to its ViewController about some events (is editing, pressed return, ) ViewController must conform with UITextFieldDelegate Protocol and implements the necessary functions Ø UITextField has a delegate property that should refer the UIViewController to communicate: can be done programmatically or via Storyboard let myfirsttextfield = UITextField(frame: CGRect(x: 100, y: 400, width: 200, height: 30)) myfirsttextfield.backgroundcolor = UIColor.yellow =.roundedrect myfirsttextfield.borderstyle self.view.addsubview(myfirsttextfield) myfirsttextfield.delegate = self func textfieldshouldreturn(_ textfield: UITextField) -> Bool { textfield.resignfirstresponder() return true

53 UIView created programmatically (greensquareview) UIView created from Storyboard UITextField created programmatically (myfirsttextfield) Keyboard automatically appears when UITextField got the focus Keyboard disappearswhenuitextfield releases focus: Call to resignfirstresponder() on delegate s function textfieldshouldreturn()

54 public protocol UITextFieldDelegate : NSObjectProtocol { A 2.0, simple *) delegation example optional public func textfieldshouldbeginediting(_ textfield: UITextField) -> Bool // return NO to disallow 2.0, *) optional public func textfielddidbeginediting(_ textfield: UITextField) // became first 2.0, *) optional public func textfieldshouldendediting(_ textfield: UITextField) -> Bool // return YES to allow editing to stop and to resign first responder status. NO to disallow the editing session to 2.0, *) optional public func textfielddidendediting(_ textfield: UITextField) // may be called if forced even if shouldendediting returns NO (e.g. view removed from window) or endediting:yes 10.0, *) optional public func textfielddidendediting(_ textfield: UITextField, reason: UITextFieldDidEndEditingReason) // if implemented, called in place of 2.0, *) optional public func textfield(_ textfield: UITextField, shouldchangecharactersin range: NSRange, replacementstring string: String) -> Bool // return NO to not change 2.0, *) optional public func textfieldshouldclear(_ textfield: UITextField) -> Bool // called when clear button pressed. return NO to ignore (no 2.0, *) optional public func textfieldshouldreturn(_ textfield: UITextField) -> Bool // called when 'return' key pressed. return NO to ignore.

55 More about ios frameworks See online documentation Labworks & project

56 API Reference

57 API Reference

58 API Reference

59 Checking API Availability Built-in support for checking API availability ensure that APIs are available on a given deployment target if #available(ios 10, macos 10.12, *) { // Use ios 10 APIs on ios, and use macos APIs on macos else { // Fall back to earlier ios and macos APIs

60 A first Hello World!

61 Hello World First steps Open Xcode! Create a new Project Select ios / Single View Application Enter Product Name: Hello World Let other fields with default value

62 Hello World Project settings Configuring a project is fundamental Which Deployment target? Devices? Version number, build What capablitities? Which languages (localizations)?

63 Hello World What it s supposed to do Have a UILabel that shows «Hello World» Have a UIButton to hide / unhide the label And that s it!

64 Hello World Main.storyboard Add a UILabel, write «Hello World» Add a UIButton, write «Tap me» Configure anything you like (size, colors, )

65 Hello World ViewController.swift Declare a IBOutlet variable to correspond the UILabel Inside the class var myfirstlabel: UILabel! Declare a IBAction function to interact with the UIButton Let s make it hide / unhide the func buttontapped() { myfirstlabel.ishidden =!myfirstlabel.ishidden

66 Hello World Connect IBOutlets and IBActions Recall: there are manyways to connect IBOutlets and IBActions Show the Assistant editor and make connections

67 Hello World Build and Run 1. Choose a simulator (ie: a screen size to test) 2. Click the Build and Run button 3. Play with your first app!

68 Next? Labworks