Building Functional Apps in Swift for iOS & OS X

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I’m @soffes

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iOS & OS X

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Sharing is Caring™

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Build for the challenge

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usewhiskey.com

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So, sharing…

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Share what makes sense.

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How can we share as much as possible?

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Touch UIKit & AppKit as little as possible.

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Clever Things Functional Things

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Functional

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Models are structs.

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struct Redaction: Hashable, Equatable { let UUID: String let type: RedactionType var rect: CGRect // ... }

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enum RedactionType: Int, Printable { case Pixelate, Blur, BlackBar var description: String { switch self { case .Pixelate: return string("PIXELATE") case .Blur: return string("BLUR") case .BlackBar: return string("BLACK_BAR") } } static var all: [RedactionType] { return [.Pixelate, .Blur, .BlackBar] } }

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private func bundle() -> NSBundle? { return NSBundle(forClass: RedactedView.self) } func string(key: String) -> String { if let bundle = bundle() { return bundle.localizedStringForKey(key, value: nil, table: nil) } return key }

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Core Image

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func filter(image: CIImage, preprocessor: Preprocessor = Redaction.preprocess) -> CIFilter { let extent = image.extent() let scaledRect = rectForBounds(extent).flippedInRect(extent) let processed = preprocessor(image: image, type: type) return CIFilter(name: "CISourceOverCompositing", withInputParameters: [ "inputImage": processed.imageByCroppingToRect(scaledRect) ]) }

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typealias Preprocessor = (image: CIImage, type: RedactionType) -> CIImage

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Function types, neat.

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static func preprocess(image: CIImage, type: RedactionType) -> CIImage { switch type { case .Pixelate: return // ... case .Blur: return // ... case .BlackBar: return // ... } }

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Is blur secure?

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5ebe2294ecd0e0f08eab7690d2a6ee69 “a” 0cc175b9c0f1b6a831c399e269772661 “b” 92eb5ffee6ae2fec3ad71c777531578f “c” 4a8a08f09d37b73795649038408b5f33 “d” 8277e0910d750195b448797616e091ad “e” e1671797c52e15f763380b45e841ec32

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281,219,526 six letter words

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281,219,526 × Type Faces × Font Sizes

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Obfuscate, then blur

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let filter = redaction.filter(image)

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Blur is slow.

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class RedactionsController { var redactions = [Redaction]() var image: UIImage? { didSet { if let image = image { ciImage = CIImage(CGImage: image.CGImage) } else { ciImage = nil } } } private var ciImage: CIImage? { didSet { updateImages() } } // ... }

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private var pixelatedImage: CIImage? private var blurredImage: CIImage? private func updateImages() { if let ciImage = ciImage { pixelatedImage = Redaction.preprocess(ciImage, type: .Pixelate) blurredImage = Redaction.preprocess(ciImage, type: .Blur) } else { pixelatedImage = nil blurredImage = nil } }

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func process() -> CIImage? { if let ciImage = ciImage { var outputImage = ciImage if redactions.count > 0 { let chain = ChainFilter() chain.inputImage = ciImage chain.inputFilters = redactions.map({ $0.filter(ciImage, preprocessor: self.preprocess) }) outputImage = chain.outputImage! } return outputImage.imageByCroppingToRect(ciImage.extent()) } return nil }

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private func preprocess(image: CIImage, type: RedactionType) -> CIImage { switch type { case .Pixelate: return pixelatedImage! case .Blur: return blurredImage! default: return Redaction.preprocess(image, type: type) } }

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Better than inheritance.

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FUNCTIONS EVERYWHERE

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Value Types

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private let redactionsController = RedactionsController() public var redactions: [Redaction] { get { return redactionsController.redactions } set { redactionsController.redactions = newValue updateRedactions() } }

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Automatic Rendering

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func updateRedactions() { image = redactionsController.process() updateSelections() }

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class CoreImageView: OpenGLView { var image: CIImage? { didSet { draw() } } // ... }

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Selection

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var selectedUUIDs = Set() { didSet { updateSelections() } }

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func isSelected(redaction: Redaction) -> Bool { return selectedUUIDs.contains(redaction.UUID) }

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func select(redaction: Redaction) { if isSelected(redaction) { return } selectedUUIDs.insert(redaction.UUID) CATransaction.begin() CATransaction.setDisableActions(true) let box = BoundingBoxLayer() boundingBoxes[redaction.UUID] = box let layer: CALayer? = self.layer layer?.addSublayer(box) updateSelections() CATransaction.commit() }

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Core Animation

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var selectedRedactions: [Redaction] { var selected = [Redaction]() let allUUIDs = redactions.map({ $0.UUID }) for UUID in selectedUUIDs { if let index = find(allUUIDs, UUID) { selected.append(redactions[index]) } } return selected }

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func updateSelections() { CATransaction.begin() CATransaction.setDisableActions(true) for redaction in selectedRedactions { if let layer = boundingBoxes[redaction.UUID] { var rect = redaction.rectForBounds(imageRect) rect.inset(dx: -2, dy: -2) layer.frame = rect } } CATransaction.commit() NSNotificationCenter.defaultCenter().postNotificationName(... }

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Dragging

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enum DraggingMode { case Creating(String) case Moving(String, CGRect, CGPoint) } var draggingMode: DraggingMode?

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public func drag(#point: CGPoint, state: GestureRecognizerState) { if image == nil { return } let point = convertPointToUnits(point) // Begin dragging if state == .Began { deselectAll() // Start moving if let redaction = hitTestRedaction(point) { draggingMode = .Moving(redaction.UUID, redaction.rect, point) select(redaction) } // Start creating else { let redaction = Redaction(type: mode, rect: CGRect(origin: point, size: .zeroSize)) draggingMode = .Creating(redaction.UUID) redactions.append(redaction) select(redaction) } }

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// Continue dragging if let draggingMode = draggingMode { switch draggingMode { case let .Creating(UUID): // Update size based on origin and current point case let .Moving(UUID, rect, startPoint): // Update rect based on original rect and start point } } // End dragging if state == .Ended { draggingMode = nil } }

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Clever Things Functional Things

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Clever Things

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#if os(iOS) import UIKit.UIFont public typealias FontType = UIFont #else import AppKit.NSFont public typealias FontType = NSFont #endif public typealias Font = FontType

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#if os(iOS) import UIKit.UIColor public typealias ColorType = UIColor #else import AppKit.NSColor public typealias ColorType = NSColor extension NSColor { public convenience init(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) { self.init(SRGBRed: red, green: green, blue: blue, alpha: alpha) } } #endif public typealias Color = ColorType

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#if os(iOS) import UIKit.UIImage public typealias ImageType = UIImage #else import AppKit.NSImage public typealias ImageType = NSImage extension NSImage { public var CGImage: CGImageRef! { return CGImageForProposedRect(nil, context: nil, hints: nil)?.takeUnretainedValue() } // Optional to match UIImage public convenience init?(CGImage cgImage: CGImageRef) { self.init(CGImage: cgImage, size: CGSizeZero) } } #endif public typealias Image = ImageType

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#if os(iOS) extension Image { public convenience init?(named name: String, inBundle bundle: NSBundle?) { self.init(named: name, inBundle: bundle, compatibleWithTraitCollection: nil) } } #endif // Mac version implemented in Objective-C

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public class View: ViewType { #if os(iOS) public var wantsLayer: Bool { set { // Do nothing } get { return true } } #else public override func viewDidMoveToWindow() { didMoveToWindow() } public func didMoveToWindow() { super.viewDidMoveToWindow() }

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ContentMode EdgeInsets Screen Window

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