Add 2048 Game

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