Add iOS

ios/Parsers/AVCaptureDevice.Format.AutoFocusSystem+descriptor.swift

@@ -0,0 +1,40 @@
+//
+//  AVCaptureDevice.Format.AutoFocusSystem+descriptor.swift
+//  Cuvent
+//
+//  Created by Marc Rousavy on 29.12.20.
+//  Copyright © 2020 Facebook. All rights reserved.
+//
+
+import AVFoundation
+
+extension AVCaptureDevice.Format.AutoFocusSystem {
+  init(withString string: String) throws {
+    switch string {
+    case "contrast-detection":
+      self = .contrastDetection
+      return
+    case "phase-detection":
+      self = .phaseDetection
+      return
+    case "none":
+      self = .none
+      return
+    default:
+      throw EnumParserError.invalidValue
+    }
+  }
+
+  var descriptor: String {
+    switch self {
+    case .contrastDetection:
+      return "contrast-detection"
+    case .phaseDetection:
+      return "phase-detection"
+    case .none:
+      return "none"
+    @unknown default:
+      fatalError("AVCaptureDevice.Format has unknown state.")
+    }
+  }
+}