Update

Other Projects/Animating Views And Transitions/Complete/Landmarks/Landmarks/Models/Data.swift

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+/*
+See LICENSE folder for this sample’s licensing information.
+
+Abstract:
+Helpers for loading images and data.
+*/
+
+import Foundation
+import CoreLocation
+import UIKit
+import SwiftUI
+
+let landmarkData: [Landmark] = load("landmarkData.json")
+let hikeData: [Hike] = load("hikeData.json")
+
+func load<T: Decodable>(_ filename: String, as type: T.Type = T.self) -> T {
+    let data: Data
+    
+    guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
+    else {
+        fatalError("Couldn't find \(filename) in main bundle.")
+    }
+    
+    do {
+        data = try Data(contentsOf: file)
+    } catch {
+        fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
+    }
+    
+    do {
+        let decoder = JSONDecoder()
+        return try decoder.decode(T.self, from: data)
+    } catch {
+        fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
+    }
+}
+
+final class ImageStore {
+    fileprivate typealias _ImageDictionary = [String: [Int: CGImage]]
+    fileprivate var images: _ImageDictionary = [:]
+
+    fileprivate static var originalSize = 250
+    fileprivate static var scale = 2
+    
+    static var shared = ImageStore()
+    
+    func image(name: String, size: Int) -> Image {
+        let index = _guaranteeInitialImage(name: name)
+        
+        let sizedImage = images.values[index][size]
+            ?? _sizeImage(images.values[index][ImageStore.originalSize]!, to: size * ImageStore.scale)
+        images.values[index][size] = sizedImage
+        
+        return Image(sizedImage, scale: Length(ImageStore.scale), label: Text(verbatim: name))
+    }
+
+    fileprivate func _guaranteeInitialImage(name: String) -> _ImageDictionary.Index {
+        if let index = images.index(forKey: name) { return index }
+        
+        guard
+            let url = Bundle.main.url(forResource: name, withExtension: "jpg"),
+            let imageSource = CGImageSourceCreateWithURL(url as NSURL, nil),
+            let image = CGImageSourceCreateImageAtIndex(imageSource, 0, nil)
+        else {
+            fatalError("Couldn't load image \(name).jpg from main bundle.")
+        }
+        
+        images[name] = [ImageStore.originalSize: image]
+        return images.index(forKey: name)!
+    }
+    
+    fileprivate func _sizeImage(_ image: CGImage, to size: Int) -> CGImage {
+        guard
+            let colorSpace = image.colorSpace,
+            let context = CGContext(
+                data: nil,
+                width: size, height: size,
+                bitsPerComponent: image.bitsPerComponent,
+                bytesPerRow: image.bytesPerRow,
+                space: colorSpace,
+                bitmapInfo: image.bitmapInfo.rawValue)
+            else {
+                fatalError("Couldn't create graphics context.")
+        }
+        context.interpolationQuality = .high
+        context.draw(image, in: CGRect(x: 0, y: 0, width: size, height: size))
+        
+        if let sizedImage = context.makeImage() {
+            return sizedImage
+        } else {
+            fatalError("Couldn't resize image.")
+        }
+    }
+}
+