[ios_platform_images] migrate objC to swift (flutter#4847)

`ios_platform_images` part of flutter/flutter#119101

Migrate ios_platform_images to Swift.

packages/ios_platform_images/AUTHORS

@@ -64,3 +64,4 @@ Aleksandr Yurkovskiy <[email protected]>
 Anton Borries <[email protected]>
 Alex Li <[email protected]>
 Rahul Raj <[email protected]>
+Mairramer <[email protected]>

packages/ios_platform_images/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.3
+
+* Migrates to a Swift implementation.
+
 ## 0.2.2+3
 
 * Converts platform communication to Pigeon.

packages/ios_platform_images/README.md

@@ -32,15 +32,15 @@ Widget build(BuildContext context) {
 }
 ```
 
-`IosPlatformImages.load` functions like [[UIImage imageNamed:]](https://developer.apple.com/documentation/uikit/uiimage/1624146-imagenamed).
+`IosPlatformImages.load` works similarly to [`UIImage(named:)`](https://developer.apple.com/documentation/uikit/uiimage/1624146-imagenamed).
 
 ### Flutter->iOS Example
 
-```objc
-#import <ios_platform_images/UIImage+ios_platform_images.h>
+```swift
+import ios_platform_images
 
-static UIImageView* MakeImage() {
-  UIImage* image = [UIImage flutterImageWithName:@"assets/foo.png"];
-  return [[UIImageView alloc] initWithImage:image];
+func makeImage() -> UIImageView {
+    let image = UIImage.flutterImageWithName("assets/foo.png")
+    return UIImageView(image: image)
 }
 ```

packages/ios_platform_images/example/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?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>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

packages/ios_platform_images/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme

@@ -20,6 +20,20 @@
                ReferencedContainer = "container:Runner.xcodeproj">
             </BuildableReference>
          </BuildActionEntry>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "NO"
+            buildForProfiling = "NO"
+            buildForArchiving = "NO"
+            buildForAnalyzing = "NO">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "F76AC1BD266713D00040C8BC"
+               BuildableName = "RunnerTests.xctest"
+               BlueprintName = "RunnerTests"
+               ReferencedContainer = "container:Runner.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
       </BuildActionEntries>
    </BuildAction>
    <TestAction

packages/ios_platform_images/example/ios/Runner/AppDelegate.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import UIKit
 import Flutter
+import UIKit
 
 @UIApplicationMain
 @objc class AppDelegate: FlutterAppDelegate {

packages/ios_platform_images/example/ios/RunnerTests/IosPlatformImagesTests.swift

@@ -0,0 +1,48 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import Flutter
+import XCTest
+
+@testable import ios_platform_images
+
+class IosPlatformImagesTests: XCTestCase {
+  let plugin = IosPlatformImagesPlugin()
+
+  func testLoadImage() {
+    let assetName = "flutter"
+    let imageData = plugin.loadImage(name: assetName)
+
+    XCTAssertNotNil(imageData)
+    XCTAssertNotNil(imageData?.data)
+  }
+
+  func testLoadImageNotFound() {
+    let assetName = "notFound"
+    let imageData = plugin.loadImage(name: assetName)
+
+    XCTAssertNil(imageData)
+  }
+
+  func testResolveURL() {
+    let resourceName = "textfile"
+    do {
+      let url = try plugin.resolveUrl(resourceName: resourceName, extension: nil)
+      XCTAssertNotNil(url)
+      XCTAssertTrue(url?.contains(resourceName) ?? false)
+    } catch {
+      XCTFail("Error while resolving URL: \(error)")
+    }
+  }
+
+  func testResolveURLNotFound() {
+    do {
+      let url = try plugin.resolveUrl(resourceName: "notFound", extension: nil)
+      XCTAssertNil(url)
+    } catch {
+      XCTFail("Error while resolving URL: \(error)")
+    }
+  }
+
+}

packages/ios_platform_images/ios/Classes/IosPlatformImagesPlugin.swift

@@ -0,0 +1,38 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import Flutter
+import Foundation
+
+public final class IosPlatformImagesPlugin: NSObject, FlutterPlugin, PlatformImagesApi {
+  public static func register(with registrar: FlutterPluginRegistrar) {
+    let instance = IosPlatformImagesPlugin()
+    let messenger = registrar.messenger()
+    PlatformImagesApiSetup.setUp(binaryMessenger: messenger, api: instance)
+  }
+
+  func loadImage(name: String) -> PlatformImageData? {
+    guard let image = UIImage(named: name),
+      let data = image.pngData()
+    else {
+      return nil
+    }
+
+    return PlatformImageData(
+      data: FlutterStandardTypedData(bytes: data), scale: Double(image.scale))
+  }
+
+  func resolveUrl(resourceName: String, extension: String?) throws -> String? {
+    guard
+      let url = Bundle.main.url(
+        forResource: resourceName,
+        withExtension: `extension`)
+    else {
+      return nil
+    }
+
+    return url.absoluteString
+  }
+
+}

packages/ios_platform_images/ios/Classes/UIImageIosPlatformImages.swift

@@ -0,0 +1,41 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import Flutter
+import Foundation
+import UIKit
+
+@objc extension UIImage {
+  /// Loads a UIImage from the embedded Flutter project's assets.
+  ///
+  /// This method loads the Flutter asset that is appropriate for the current
+  /// screen.  If you are on a 2x retina device where usually `UIImage` would be
+  /// loading `@2x` assets, it will attempt to load the `2.0x` variant.  It will
+  /// load the standard image if it can't find the `2.0x` variant.
+  ///
+  /// For example, if your Flutter project's `pubspec.yaml` lists "assets/foo.png"
+  /// and "assets/2.0x/foo.png", calling
+  /// `[UIImage flutterImageWithName:@"assets/foo.png"]` will load
+  /// "assets/2.0x/foo.png".
+  ///
+  /// See also https://flutter.dev/docs/development/ui/assets-and-images
+  ///
+  /// Note: We don't yet support images from package dependencies (ex.
+  /// `AssetImage('icons/heart.png', package: 'my_icons')`).
+  public static func flutterImageWithName(_ name: String) -> UIImage? {
+    let filename = (name as NSString).lastPathComponent
+    let path = (name as NSString).deletingLastPathComponent
+
+    for screenScale in stride(from: Int(UIScreen.main.scale), to: 1, by: -1) {
+      // TODO(hellohuanlin): Fix duplicate slashes in this path construction.
+      let key = FlutterDartProject.lookupKey(forAsset: "\(path)/\(screenScale).0x/\(filename)")
+      if let image = UIImage(named: key, in: Bundle.main, compatibleWith: nil) {
+        return image
+      }
+    }
+
+    let key = FlutterDartProject.lookupKey(forAsset: name)
+    return UIImage(named: key, in: Bundle.main, compatibleWith: nil)
+  }
+}