Add 2048 Game

Examples/2048 Game/SwiftUI2048/AppDelegate.swift

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+//
+//  AppDelegate.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import UIKit
+import SwiftUI
+
+@UIApplicationMain
+class AppDelegate: UIResponder, UIApplicationDelegate {
+
+    var gameLogic: GameLogic!
+    var window: UIWindow?
+    
+    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
+        
+        gameLogic = GameLogic()
+        
+        window = UIWindow(frame: UIScreen.main.bounds)
+        window!.rootViewController = UIHostingController(rootView:
+            GameView().environmentObject(gameLogic)
+        )
+        window!.makeKeyAndVisible()
+        
+        self.becomeFirstResponder()
+        
+        return true
+    }
+
+    func applicationWillTerminate(_ application: UIApplication) {
+        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
+    }
+    
+    @objc func newGame(_ sender: AnyObject?) {
+        gameLogic.newGame()
+    }
+    
+    override func buildCommands(with builder: UICommandBuilder) {
+        builder.remove(menu: .edit)
+        builder.remove(menu: .format)
+        builder.remove(menu: .view)
+        
+        builder.replaceChildren(ofMenu: .file) { oldChildren in
+            var newChildren = oldChildren
+            let newGameItem = UIMutableKeyCommand(input: "N",
+                                                  modifierFlags: .command,
+                                                  action: #selector(newGame(_:)))
+            newGameItem.title = "New Game"
+            newChildren.insert(newGameItem, at: 0)
+            return newChildren
+        }
+    }
+
+}
+

Examples/2048 Game/SwiftUI2048/Assets.xcassets/AppIcon.appiconset/Contents.json

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+{
+  "images" : [
+    {
+      "idiom" : "iphone",
+      "size" : "20x20",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "20x20",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "29x29",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "29x29",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "40x40",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "40x40",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "60x60",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "60x60",
+      "scale" : "3x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "20x20",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "20x20",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "29x29",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "29x29",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "40x40",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "40x40",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "76x76",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "76x76",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ipad",
+      "size" : "83.5x83.5",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "ios-marketing",
+      "size" : "1024x1024",
+      "scale" : "1x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

Examples/2048 Game/SwiftUI2048/Assets.xcassets/Contents.json

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+{
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

Examples/2048 Game/SwiftUI2048/Base.lproj/LaunchScreen.storyboard

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+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14810.11" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" launchScreen="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="01J-lp-oVM">
+    <device id="retina6_1" orientation="portrait" appearance="light"/>
+    <dependencies>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14766.13"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <scenes>
+        <!--View Controller-->
+        <scene sceneID="EHf-IW-A2E">
+            <objects>
+                <viewController id="01J-lp-oVM" sceneMemberID="viewController">
+                    <view key="view" contentMode="scaleToFill" id="Ze5-6b-2t3">
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <color key="backgroundColor" xcode11CocoaTouchSystemColor="systemBackgroundColor" cocoaTouchSystemColor="whiteColor"/>
+                        <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
+                    </view>
+                </viewController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="iYj-Kq-Ea1" userLabel="First Responder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="53" y="375"/>
+        </scene>
+    </scenes>
+</document>

Examples/2048 Game/SwiftUI2048/FunctionalUtils.swift

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+//
+//  FunctionalUtils.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import Foundation
+
+func bind<T, U>(_ x: T, _ closure: (T) -> U) -> U {
+    return closure(x)
+}

Examples/2048 Game/SwiftUI2048/Info.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>$(DEVELOPMENT_LANGUAGE)</string>
+	<key>CFBundleDisplayName</key>
+	<string>2048</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>$(PRODUCT_BUNDLE_PACKAGE_TYPE)</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+	<key>LSRequiresIPhoneOS</key>
+	<true/>
+	<key>UILaunchStoryboardName</key>
+	<string>LaunchScreen</string>
+	<key>UIRequiredDeviceCapabilities</key>
+	<array>
+		<string>armv7</string>
+	</array>
+	<key>UISupportedInterfaceOrientations</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+	<key>UISupportedInterfaceOrientations~ipad</key>
+	<array>
+		<string>UIInterfaceOrientationPortrait</string>
+		<string>UIInterfaceOrientationPortraitUpsideDown</string>
+		<string>UIInterfaceOrientationLandscapeLeft</string>
+		<string>UIInterfaceOrientationLandscapeRight</string>
+	</array>
+</dict>
+</plist>

Examples/2048 Game/SwiftUI2048/MainMenu.xib

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+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="14810.11" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES">
+    <device id="retina6_1" orientation="portrait" appearance="light"/>
+    <dependencies>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14766.13"/>
+    </dependencies>
+    <objects>
+        <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner" customClass="AppDelegate" customModule="_048"/>
+        <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
+        <command title="New Game" input="n" id="TrP-zF-WNW">
+            <keyModifierFlags key="modifierFlags" command="YES"/>
+            <alternates>
+                <commandAlternate title="a" actionName="newGame:" id="Fnd-9b-r2T"/>
+            </alternates>
+            <connections>
+                <action selector="newGame:" destination="-2" id="AQs-UV-nU7"/>
+            </connections>
+        </command>
+    </objects>
+</document>

Examples/2048 Game/SwiftUI2048/Models/BlockMatrix.swift

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+//
+//  BlockMatrix.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import Foundation
+
+protocol Block {
+    
+    associatedtype Value
+    
+    var number: Value { get set }
+    
+}
+
+struct IndexedBlock<T> {
+    
+    let index: (Int, Int)
+    let item: T?
+
+}
+
+struct BlockMatrix<T> : CustomDebugStringConvertible where T: Block {
+    
+    typealias Index = (Int, Int)
+    
+    fileprivate var matrix: [[T?]]
+    
+    init() {
+        matrix = [[T?]]()
+        for _ in 0..<4 {
+            var row = [T?]()
+            for _ in 0..<4 {
+                row.append(nil)
+            }
+            matrix.append(row)
+        }
+    }
+    
+    var debugDescription: String {
+        matrix.map { row -> String in
+            row.map {
+                if $0 == nil {
+                    return " "
+                } else {
+                    return String(describing: $0!.number)
+                }
+            }.joined(separator: "\t")
+        }.joined(separator: "\n")
+    }
+    
+    var flatten: [IndexedBlock<T>] {
+        return self.matrix.enumerated().flatMap { (y: Int, element: [T?]) in
+            element.enumerated().map { (x: Int, element: T?) in
+                return IndexedBlock(index: (x, y), item: element)
+            }
+        }
+    }
+    
+    subscript(index: Self.Index) -> T? {
+        guard isIndexValid(index) else {
+            return nil
+        }
+        
+        return matrix[index.1][index.0]
+    }
+    
+    /// Move the block to specific location and leave the original location blank.
+    /// - Parameter from: Source location
+    /// - Parameter to: Destination location
+    mutating func move(from: Self.Index, to: Self.Index) {
+        guard isIndexValid(from) && isIndexValid(to) else {
+            // TODO: Throw an error?
+            return
+        }
+        
+        guard let source = self[from] else {
+            return
+        }
+        
+        matrix[to.1][to.0] = source
+        matrix[from.1][from.0] = nil
+    }
+    
+    /// Move the block to specific location, change its value and leave the original location blank.
+    /// - Parameter from: Source location
+    /// - Parameter to: Destination location
+    /// - Parameter newValue: The new value
+    mutating func move(from: Self.Index, to: Self.Index, with newValue: T.Value) {
+        guard isIndexValid(from) && isIndexValid(to) else {
+            // TODO: Throw an error?
+            return
+        }
+        
+        guard var source = self[from] else {
+            return
+        }
+        
+        source.number = newValue
+        
+        matrix[to.1][to.0] = source
+        matrix[from.1][from.0] = nil
+    }
+    
+    /// Place a block to specific location.
+    /// - Parameter block: The block to place
+    /// - Parameter to: Destination location
+    mutating func place(_ block: T?, to: Self.Index) {
+        matrix[to.1][to.0] = block
+    }
+    
+    fileprivate func isIndexValid(_ index: Self.Index) -> Bool {
+        guard index.0 >= 0 && index.0 < 4 else {
+            return false
+        }
+        
+        guard index.1 >= 0 && index.1 < 4 else {
+            return false
+        }
+        
+        return true
+    }
+    
+}

Examples/2048 Game/SwiftUI2048/Models/GameLogic.swift

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+//
+//  GameLogic.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import Foundation
+import SwiftUI
+import Combine
+
+final class GameLogic : BindableObject {
+    
+    enum Direction {
+        case left
+        case right
+        case up
+        case down
+    }
+    
+    typealias BlockMatrixType = BlockMatrix<IdentifiedBlock>
+    
+    let didChange = PassthroughSubject<GameLogic, Never>()
+    
+    fileprivate var _blockMatrix: BlockMatrixType!
+    var blockMatrix: BlockMatrixType {
+        return _blockMatrix
+    }
+    
+    fileprivate var _globalID = 0
+    fileprivate var newGlobalID: Int {
+        _globalID += 1
+        return _globalID
+    }
+    
+    init() {
+        newGame()
+    }
+    
+    func newGame() {
+        _blockMatrix = BlockMatrixType()
+        generateNewBlocks()
+        
+        didChange.send(self)
+    }
+    
+    func move(_ direction: Direction) {
+        defer {
+            didChange.send(self)
+        }
+        
+        var moved = false
+        
+        let axis = direction == .left || direction == .right
+        for row in 0..<4 {
+            var rowSnapshot = [IdentifiedBlock?]()
+            var compactRow = [IdentifiedBlock]()
+            for col in 0..<4 {
+                // Transpose if necessary.
+                if let block = _blockMatrix[axis ? (col, row) : (row, col)] {
+                    rowSnapshot.append(block)
+                    compactRow.append(block)
+                }
+                rowSnapshot.append(nil)
+            }
+            
+            merge(blocks: &compactRow, reverse: direction == .down || direction == .right)
+            
+            var newRow = [IdentifiedBlock?]()
+            compactRow.forEach { newRow.append($0) }
+            if compactRow.count < 4 {
+                for _ in 0..<(4 - compactRow.count) {
+                    if direction == .left || direction == .up {
+                        newRow.append(nil)
+                    } else {
+                        newRow.insert(nil, at: 0)
+                    }
+                }
+            }
+            
+            newRow.enumerated().forEach {
+                if rowSnapshot[$0]?.number != $1?.number {
+                    moved = true
+                }
+                _blockMatrix.place($1, to: axis ? ($0, row) : (row, $0))
+            }
+        }
+        
+        if moved {
+            generateNewBlocks()
+        }
+    }
+    
+    fileprivate func merge(blocks: inout [IdentifiedBlock], reverse: Bool) {
+        if reverse {
+            blocks = blocks.reversed()
+        }
+        
+        blocks = blocks
+            .map { (false, $0) }
+            .reduce([(Bool, IdentifiedBlock)]()) { acc, item in
+                if acc.last?.0 == false && acc.last?.1.number == item.1.number {
+                    var accPrefix = Array(acc.dropLast())
+                    var mergedBlock = item.1
+                    mergedBlock.number *= 2
+                    accPrefix.append((true, mergedBlock))
+                    return accPrefix
+                } else {
+                    var accTmp = acc
+                    accTmp.append((false, item.1))
+                    return accTmp
+                }
+            }
+            .map { $0.1 }
+        
+        if reverse {
+            blocks = blocks.reversed()
+        }
+    }
+    
+    @discardableResult fileprivate func generateNewBlocks() -> Bool {
+        var blankLocations = [BlockMatrixType.Index]()
+        for rowIndex in 0..<4 {
+            for colIndex in 0..<4 {
+                let index = (colIndex, rowIndex)
+                if _blockMatrix[index] == nil {
+                    blankLocations.append(index)
+                }
+            }
+        }
+        
+        guard blankLocations.count >= 2 else {
+            return false
+        }
+        
+        // Don't forget to sync data.
+        defer {
+            didChange.send(self)
+        }
+        
+        // Place the first block.
+        var placeLocIndex = Int.random(in: 0..<blankLocations.count)
+        _blockMatrix.place(IdentifiedBlock(id: newGlobalID, number: 2), to: blankLocations[placeLocIndex])
+        
+        // Place the second block.
+        guard let lastLoc = blankLocations.last else {
+            return false
+        }
+        blankLocations[placeLocIndex] = lastLoc
+        placeLocIndex = Int.random(in: 0..<(blankLocations.count - 1))
+        _blockMatrix.place(IdentifiedBlock(id: newGlobalID, number: 2), to: blankLocations[placeLocIndex])
+        
+        return true
+    }
+    
+//    fileprivate func forEachBlockIndices(mode: ForEachMode = .rowByRow,
+//                                         reversed: Bool = false,
+//                                         _ action: (BlockMatrixType.Index) -> ()) {
+//        var indices = (0..<4).map { $0 }
+//        if reversed {
+//            indices = indices.reversed()
+//        }
+//
+//        for row in indices {
+//            for col in indices {
+//                if mode == .rowByRow {
+//                    action((col, row))
+//                } else {
+//                    action((row, col))  // transpose
+//                }
+//            }
+//        }
+//    }
+    
+}

Examples/2048 Game/SwiftUI2048/Models/IdentifiedBlock.swift

@@ -0,0 +1,16 @@
+//
+//  IdentifiedBlock.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import Foundation
+
+struct IdentifiedBlock: Block {
+    
+    let id: Int
+    var number: Int
+    
+}

Examples/2048 Game/SwiftUI2048/Preview Content/Preview Assets.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

Examples/2048 Game/SwiftUI2048/SwiftUI2048.entitlements

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.security.app-sandbox</key>
+	<true/>
+	<key>com.apple.security.network.client</key>
+	<true/>
+</dict>
+</plist>

Examples/2048 Game/SwiftUI2048/Views/BlockGridView.swift

@@ -0,0 +1,116 @@
+//
+//  BlockGridView.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import SwiftUI
+
+fileprivate struct IdentifiableIndexedBlock : Identifiable {
+    
+    typealias ID = String
+    typealias IdentifiedValue = IndexedBlock<IdentifiedBlock>
+    
+    static var uniqueBlankId = 0
+    
+    let indexedBlock: IndexedBlock<IdentifiedBlock>
+    
+    var id: Self.ID {
+        if let id = indexedBlock.item?.id {
+            return "\(id)"
+        }
+        
+        // TODO: (Refactor) Don't mix two types of block views.
+        IdentifiableIndexedBlock.uniqueBlankId += 1
+        return "Blank_\(IdentifiableIndexedBlock.uniqueBlankId)"
+    }
+    
+    var identifiedValue: Self.IdentifiedValue {
+        return indexedBlock
+    }
+    
+}
+
+extension AnyTransition {
+    
+    static func blockAppear(from: Edge) -> AnyTransition {
+        return .asymmetric(
+            insertion: AnyTransition.opacity
+                .combined(with: .move(edge: from)),
+            removal: .identity)
+    }
+    
+}
+
+struct BlockGridView : View {
+    
+    typealias SupportingMatrix = BlockMatrix<IdentifiedBlock>
+    
+    let matrix: Self.SupportingMatrix
+    let blockEnterEdge: Edge
+    
+    func createBlock(_ block: IdentifiedBlock?) -> some View {
+        if let block = block {
+            return BlockView(number: block.number)
+        }
+        return BlockView.blank()
+    }
+    
+    // FIXME: This is existed as a workaround for a Swift compiler bug.
+    func zIndex(_ block: IdentifiedBlock?) -> Double {
+        if block == nil {
+            return 1
+        }
+        return 1000
+    }
+    
+    var body: some View {
+        ZStack {
+            ForEach(
+                self.matrix.flatten.map { IdentifiableIndexedBlock(indexedBlock: $0) }
+            ) { block in
+                self.createBlock(block.item)
+                    .frame(width: 65, height: 65, alignment: .center)
+                    .position(x: CGFloat(block.index.0) * (65 + 12) + 32.5 + 12,
+                              y: CGFloat(block.index.1) * (65 + 12) + 32.5 + 12)
+                    .zIndex(self.zIndex(block.item))
+                    .transition(.blockAppear(from: self.blockEnterEdge))
+                    .animation(block.item == nil ? nil : .spring(mass: 1, stiffness: 400, damping: 56, initialVelocity: 0))
+            }
+        }
+        .frame(width: 320, height: 320, alignment: .center)
+        .background(
+            Rectangle()
+                .fill(Color(red:0.72, green:0.66, blue:0.63, opacity:1.00))
+        )
+        .clipped()
+        .cornerRadius(6)
+    }
+    
+}
+
+#if DEBUG
+struct BlockGridView_Previews : PreviewProvider {
+    
+    static var matrix: BlockGridView.SupportingMatrix {
+        var _matrix = BlockGridView.SupportingMatrix()
+        _matrix.place(IdentifiedBlock(id: 1, number: 2), to: (2, 0))
+        _matrix.place(IdentifiedBlock(id: 2, number: 2), to: (3, 0))
+        _matrix.place(IdentifiedBlock(id: 3, number: 8), to: (1, 1))
+        _matrix.place(IdentifiedBlock(id: 4, number: 4), to: (2, 1))
+        _matrix.place(IdentifiedBlock(id: 5, number: 512), to: (3, 3))
+        _matrix.place(IdentifiedBlock(id: 6, number: 1024), to: (2, 3))
+        _matrix.place(IdentifiedBlock(id: 7, number: 16), to: (0, 3))
+        _matrix.place(IdentifiedBlock(id: 8, number: 8), to: (1, 3))
+        return _matrix
+    }
+    
+    static var previews: some View {
+        BlockGridView(matrix: matrix, blockEnterEdge: .top)
+            .previewLayout(.sizeThatFits)
+    }
+    
+}
+#endif

Examples/2048 Game/SwiftUI2048/Views/BlockView.swift

@@ -0,0 +1,118 @@
+//
+//  BlockView.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import SwiftUI
+
+struct BlockView : View {
+    
+    fileprivate let colorScheme: [(Color, Color)] = [
+        // 2
+        (Color(red:0.91, green:0.87, blue:0.83, opacity:1.00), Color(red:0.42, green:0.39, blue:0.35, opacity:1.00)),
+        // 4
+        (Color(red:0.90, green:0.86, blue:0.76, opacity:1.00), Color(red:0.42, green:0.39, blue:0.35, opacity:1.00)),
+        // 8
+        (Color(red:0.93, green:0.67, blue:0.46, opacity:1.00), Color.white),
+        // 16
+        (Color(red:0.94, green:0.57, blue:0.38, opacity:1.00), Color.white),
+        // 32
+        (Color(red:0.95, green:0.46, blue:0.33, opacity:1.00), Color.white),
+        // 64
+        (Color(red:0.94, green:0.35, blue:0.23, opacity:1.00), Color.white),
+        // 128
+        (Color(red:0.91, green:0.78, blue:0.43, opacity:1.00), Color.white),
+        // 256
+        (Color(red:0.91, green:0.78, blue:0.37, opacity:1.00), Color.white),
+        // 512
+        (Color(red:0.90, green:0.77, blue:0.31, opacity:1.00), Color.white),
+        // 1024
+        (Color(red:0.91, green:0.75, blue:0.24, opacity:1.00), Color.white),
+        // 2048
+        (Color(red:0.91, green:0.74, blue:0.18, opacity:1.00), Color.white),
+    ]
+    
+    fileprivate let number: Int?
+    
+    init(number: Int) {
+        self.number = number
+    }
+    
+    fileprivate init() {
+        self.number = nil
+    }
+    
+    static func blank() -> Self {
+        return self.init()
+    }
+    
+    fileprivate var numberText: String {
+        guard let number = number else {
+            return ""
+        }
+        return String(number)
+    }
+    
+    fileprivate var fontSize: CGFloat {
+        let textLength = numberText.count
+        if textLength < 3 {
+            return 32
+        } else if textLength < 4 {
+            return 18
+        } else {
+            return 12
+        }
+    }
+    
+    fileprivate var colorPair: (Color, Color) {
+        guard let number = number else {
+            return (Color(red:0.78, green:0.73, blue:0.68, opacity:1.00), Color.black)
+        }
+        let index = Int(log2(Double(number))) - 1
+        if index < 0 || index >= colorScheme.count {
+            fatalError("No color for such number")
+        }
+        return colorScheme[index]
+    }
+    
+    // MARK: Body
+    
+    var body: some View {
+        ZStack {
+            Rectangle().fill(colorPair.0)
+            
+            Text(numberText)
+                .font(Font.system(size: fontSize).bold())
+                .color(colorPair.1)
+                .id(numberText)
+                .transition(AnyTransition.scale(scale: 0.5, anchor: .center).combined(with: .opacity))
+                .animation(.fluidSpring())
+        }
+        .clipped()
+        .cornerRadius(6)
+    }
+    
+}
+
+// MARK: - Previews
+
+#if DEBUG
+struct BlockView_Previews : PreviewProvider {
+    
+    static var previews: some View {
+        Group {
+            ForEach((1...11).map { Int(pow(2, Double($0))) }) { i in
+                BlockView(number: i)
+                    .previewLayout(.sizeThatFits)
+            }
+            
+            BlockView.blank()
+                .previewLayout(.sizeThatFits)
+        }
+    }
+    
+}
+#endif

Examples/2048 Game/SwiftUI2048/Views/GameView.swift

@@ -0,0 +1,127 @@
+//
+//  GameView.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import SwiftUI
+
+extension Edge {
+    
+    static func from(_ from: GameLogic.Direction) -> Self {
+        switch from {
+        case .down:
+            return .top
+        case .up:
+            return .bottom
+        case .left:
+            return .trailing
+        case .right:
+            return .leading
+        }
+    }
+    
+}
+
+struct GameView : View {
+    
+    @State var gestureStartLocation: CGPoint = .zero
+    @State var lastGestureDirection: GameLogic.Direction = .up
+    @EnvironmentObject var gameLogic: GameLogic
+    
+    fileprivate struct LayoutTraits {
+        let bannerOffset: CGSize
+        let containerAlignment: Alignment
+    }
+    
+    fileprivate func layoutTraits(`for` proxy: GeometryProxy) -> LayoutTraits {
+        let landscape = proxy.size.width > proxy.size.height
+        
+        return LayoutTraits(
+            bannerOffset: landscape
+                ? .init(width: proxy.safeAreaInsets.leading + 32, height: 0)
+                : .init(width: 0, height: proxy.safeAreaInsets.top + 32),
+            containerAlignment: landscape ? .leading : .top
+        )
+    }
+    
+    var gesture: some Gesture {
+        let threshold: CGFloat = 44
+        let drag = DragGesture()
+            .onChanged { v in
+                guard self.gestureStartLocation != v.startLocation else { return }
+                
+                withTransaction(Transaction()) {
+                    self.gestureStartLocation = v.startLocation
+                    
+                    if v.translation.width > threshold {
+                        // Move right
+                        self.gameLogic.move(.right)
+                        self.lastGestureDirection = .right
+                    } else if v.translation.width < -threshold {
+                        // Move left
+                        self.gameLogic.move(.left)
+                        self.lastGestureDirection = .left
+                    } else if v.translation.height > threshold {
+                        // Move down
+                        self.gameLogic.move(.down)
+                        self.lastGestureDirection = .down
+                    } else if v.translation.height < -threshold {
+                        // Move up
+                        self.gameLogic.move(.up)
+                        self.lastGestureDirection = .up
+                    } else {
+                        // Direction cannot be deduced, reset gesture state.
+                        self.gestureStartLocation = .zero
+                    }
+                }
+                
+                // After the scene is updated, reset the last gesture direction
+                // to make sure the animation is right when user starts a new
+                // game.
+                OperationQueue.main.addOperation {
+                    self.lastGestureDirection = .up
+                }
+            }
+        return drag
+    }
+    
+    var body: some View {
+        GeometryReader { proxy in
+            bind(self.layoutTraits(for: proxy)) { layoutTraits in
+                ZStack(alignment: layoutTraits.containerAlignment) {
+                    Text("2048")
+                        .font(Font.system(size: 48).weight(.black))
+                        .color(Color(red:0.47, green:0.43, blue:0.40, opacity:1.00))
+                        .offset(layoutTraits.bannerOffset)
+                    
+                    ZStack(alignment: .top) {
+                        BlockGridView(matrix: self.gameLogic.blockMatrix,
+                                      blockEnterEdge: .from(self.lastGestureDirection))
+                            .gesture(self.gesture)
+                        }
+                        .frame(width: proxy.size.width, height: proxy.size.height, alignment: .center)
+                    }
+                    .frame(width: proxy.size.width, height: proxy.size.height, alignment: .center)
+                    .background(
+                        Rectangle().fill(Color(red:0.96, green:0.94, blue:0.90, opacity:1.00))
+                )
+            }
+        }
+        .edgesIgnoringSafeArea(.all)
+    }
+    
+}
+
+#if DEBUG
+struct GameView_Previews : PreviewProvider {
+    
+    static var previews: some View {
+        GameView()
+            .environmentObject(GameLogic())
+    }
+    
+}
+#endif