use app extension safe APIs

Author: Nikolay Derkach

Example/QRCodeReader.swift.xcodeproj/project.pbxproj

@@ -642,6 +642,7 @@
 		CE8FFEED1BAB4E8000D43F38 /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "";
 				CURRENT_PROJECT_VERSION = 1;
 				DEBUG_INFORMATION_FORMAT = dwarf;
@@ -666,6 +667,7 @@
 		CE8FFEEE1BAB4E8000D43F38 /* Release */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
+				APPLICATION_EXTENSION_API_ONLY = YES;
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "";
 				COPY_PHASE_STRIP = NO;
 				CURRENT_PROJECT_VERSION = 1;

Sources/QRCodeReaderView.swift

@@ -154,8 +154,7 @@ final public class QRCodeReaderView: UIView, QRCodeReaderDisplayable {
 
     overlayView?.setNeedsDisplay()
 
-    if let connection = reader?.previewLayer.connection, connection.isVideoOrientationSupported {
-      let application                    = UIApplication.shared
+    if let connection = reader?.previewLayer.connection, connection.isVideoOrientationSupported, let application = QRCodeReaderView.sharedApplication {
       let orientation                    = UIDevice.current.orientation
       let supportedInterfaceOrientations = application.supportedInterfaceOrientations(for: application.keyWindow)
 
@@ -165,6 +164,11 @@ final public class QRCodeReaderView: UIView, QRCodeReaderDisplayable {
 
   // MARK: - Convenience Methods
 
+  private class var sharedApplication: UIApplication? {
+    let selector = NSSelectorFromString("sharedApplication")
+    return UIApplication.perform(selector)?.takeRetainedValue() as? UIApplication
+  }
+
   private func addComponents() {
     #if swift(>=4.2)
     let notificationName = UIDevice.orientationDidChangeNotification