Add iOS

ios/CameraView+Focus.swift

@@ -0,0 +1,42 @@
+//
+//  CameraView+focus.swift
+//  Cuvent
+//
+//  Created by Marc Rousavy on 19.02.21.
+//  Copyright © 2021 Facebook. All rights reserved.
+//
+
+import Foundation
+
+extension CameraView {
+  
+  func focus(point: CGPoint, promise: Promise) {
+    withPromise(promise) {
+      guard let device = self.videoDeviceInput?.device else {
+        throw CameraError.session(SessionError.cameraNotReady)
+      }
+      if !device.isFocusPointOfInterestSupported {
+        throw CameraError.device(DeviceError.focusNotSupported)
+      }
+      
+      let normalizedPoint = self.videoPreviewLayer.captureDevicePointConverted(fromLayerPoint: point)
+      
+      do {
+        try device.lockForConfiguration()
+        
+        device.focusPointOfInterest = normalizedPoint
+        device.focusMode = .continuousAutoFocus
+        
+        if device.isExposurePointOfInterestSupported {
+          device.exposurePointOfInterest = normalizedPoint
+          device.exposureMode = .continuousAutoExposure
+        }
+        
+        device.unlockForConfiguration()
+        return nil
+      } catch {
+        throw CameraError.device(DeviceError.configureError)
+      }
+    }
+  }
+}