Sound #

• Provide data to OS
• OS decices, what to show (or if anything is shown at all)
• => best practice: supply as much info as possible
• AVAudioPlayer
  • Play audio (from file or buffer)
  • Control volume, panning, looping, ...
• AVAudioSession: Intermediary between the app & OS
  • Categories:
    • ambient: Audio is non-primary (app works without sound): Instagram, Reddit, ...
    • soloAmbient: Ambient, but max. 1 source can play
    • playback: Controls appear; for example in a music player
    • record, playAndRecord: Recording (not in the Seminar)
• "Now playing"
  • Update MPNowPlayingInfoCenter.nowPlayingInfo (Dict)
  • No idea which keys to use for that

Haptics #

• Uses UIFeedbackGenerator; three subclasses:
  • UIImpactFeedbackGenerator: when UI element collides with something, something snaps into place, ...
  • UISelectionFeedbackGenerator: when a change in selection occurs
  • UINotificationFeedbackSelection: indicate success, failure, or warning
• Guidelines:
  • Use according to documented meaning
  • Be consistent
  • Accompany with sound & visuals
  • Give option to turn haptics off
• Usage:

1var generator = UIImpactFeedbackGenerator(style: .heavy)
2generator.prepare()
3generator.impactOccured()
4generator = nil  // Release to allow TapticEngine to sleep

Rich articles #

• UILabel: Read-only labels
• UITextView: Scrollable, multi-line - supports text editing & NSAttributedStrings
• NSAttributedString: String that contains attributes (like Markdown, HTML, ...)
  • NSParagraphStyle: Style of an NSAttributedString's segment
  • Editable subclass: NSMutableAttributedString, uses NSMutableParagraphStyle
  • Use-cases: Images in text, rendering HTML (using own styles)
• WKWebView: Render Website inside of your app
  • Integrates into your app (unlike SFSafariViewController, which essentially opens Safari)

ARKit #

Requirements:

• iOS 11.0 or later
• A9 processor or later
• Camera access permission

• ARSession: Controls camera & motion, performs image analysis
• ARConfiguration: determines camera & tracking algorithm
  • Back Camera: WorldTracking (Plane/image/object detecion)
  • Front Camera: FaceTracking
• Use ARCoachingOverlayView for onboarding instructions
• Anchors: Identify item positions
  • Options: ARPlaneAnchor, ARObjectAnchor, ARBodyAnchor, ARBodyAnchor (track position & movement of human body), ARFaceAnchor (face detection, needs front-facing camera), ARImageAnchor
• Rendering views:
  • ARSCNView ("AR-Scene View", from SceneKit)
  • ARView: RealityKit
  • ARSKView: SpriteKit
  • Custom Metal rendering
• Use ARRaycastQuery & ARRaycastResult for raycasts

MapKit #

Embed maps (with custom annotations)

• MKPointAnnotation: Add annotations (balloon-shaped)
  • Customaisable Color, Title, Icon, ...
  • Can cluster
• Overlays: geometric shapes (Circles, Lines, Images, Text, Polygons)
• GeoJSON: Schema for location data (JSON-based)
  • MapKit has a parser
  • Can be used for indoor maps

Features requiring Apple Services #

• Local Search (search around your current location)
• Look Around (aka Streetview)
• Navigation (no customization options)

Core Image #

• Import different images, apply filters, find prominent features
• CIImage: Image data
• UIImage: Picture, image as complete drawing
• UIImageView: Renders picture

Filters (CIFilter) #

• Apply to CIImage(s): n CIImages to one
• Examples: Blur, Sharpen, ...
• Can be combined into one
• Write custom ones in GLSL

CIDetector #

• Identifies notable features (CIFeatures)
• Examples: Faces, Rects, QR-Codes, Text
• On Image or Video
• Heavy constructor, make sure to reuse

Advanced Functions #

• CIContext: memory management, hardware comm.
• CIColor
• CIRender: render settings
• CIPlugin

Advanced SwiftUI #

• GeometryReader: Get size & position of object
• Layout priorities: determine sizes
• Fixed sizes
• Alignment guides: defaults to .center (other options: .bottom, .firstTextBaseline, ...)
  • Supports computeValue as parameter
  • Can implement custom alignments

SpriteKit #

• For game devs that don't know about game engines
• SKScene: contains tree of SKNodes
• Load scenes from .sks file
• Anchor Points are variable (the point to rotate around)
• UIResponer: touch/press/motion/remove-control events
• SKAction: modify nodes (animated)
• SKPhysics: physics simulation

Core Animation #

Layers #

• Base element: CALayers
• Can have subelements
• Masks, cornerRadius

Animations #

• Use .fromValue & .toValue
• Target: .keyPath
• .isRemovedOnCompletion
• Start with layer.add(animation)
• Uses CIPaths and CIShapes for specification
• CADisplayLink: write your own update function

WatchOS #

• Limitations: Size, Battery
• Differing sensors
• Dependent (companion) vs. independent app

Guidelines #

• Keep interactions short
• Max 2/3 controls per row
• Use notifications

WKInterface & SwiftUI #

• WKInterface: (Limited) UIKit clone for watchOS - deprecated
• SwiftUI: preffered, no watch-specific code

Connectivity #

• Use WCSession(Delegate): WiFi or Bluetooth
• Works on dictionaries
• sendMessage: immediate
• transferFile: send file, might just not send if size is too large
• updateApplicationContext:
• transferUserInfo:

Working with files #

• Display files: UIDocumentBrowser (local & cloud documents)

FileManager #

• Create/read/update/delete
• Check existance
• Copy
• Can't append

FileHandle #

• Read/write/update

UIPresentationController #

• Handles transitions between ViewControllers
• Examples: UISheetPresentationController, UIPopoverPresentationController

Custom PresentationController #

• TransitioningDelegate: selects PresentationController, AnimationController
• PresentationController: Add/remove views
• AnimationController: Perform animations, define duration
• Use UIPercentDrivenInteractiveTransition (instead of AnimationController) for interactive transition
• Respect device type: UIAdaptivePresentationControllerDelegate

CoreData #

• Persist data
• Uses PersistentContainer for storage (SQLite, XML, CloudKit, ...)
• Tracks relations (delete rules: none, nullify, cascade, deny)
• Create model in XCode
• Entity (table), Attributes (column) & Managed Objects (row)
• Use NSFetchRequests for queries, NSPredicates for filtering

Combine #

• Pub-sub (for async events)
• Can publish failures (errors)
• Build using .publisher(for: ...), Subscribers.Assign(object: ..., keyPath: ...)
• Custom publishers: Publisher protocol

Operators #

• .subscribe(_: Subscriber)

• .receive(on: Scheduler)

• .sink() {...}: Receive to closure

• .assign(to: path, on: object): update variable

• .map

• .tryMap

• .mapError

• .encode/.decode

• .filter

• .removeDuplicates

• Zip

• Combine latest

Integrations #

• SwiftUI: @ObservedObject, @Published
• Foundation (URLSession, NotificationCenter, Timer)
• CoreData: FetchedRequest

CreateML/CoreML #

• Predict, customize, encrypt, personalize
• Runs on-device
• Convert other models using Python script
• CreateML: train from example input sets