fix(ios): exit event not fired on swipe down (apache#737)

Author: jcesarmobile

src/ios/CDVWKInAppBrowser.h

@@ -49,7 +49,7 @@
 
 @end
 
-@interface CDVWKInAppBrowserViewController : UIViewController <CDVScreenOrientationDelegate,WKNavigationDelegate,WKUIDelegate,WKScriptMessageHandler>{
+@interface CDVWKInAppBrowserViewController : UIViewController <CDVScreenOrientationDelegate,WKNavigationDelegate,WKUIDelegate,WKScriptMessageHandler,UIAdaptivePresentationControllerDelegate>{
     @private
     CDVInAppBrowserOptions *_browserOptions;
     NSDictionary *_settings;

src/ios/CDVWKInAppBrowser.m

@@ -290,6 +290,7 @@ - (void)show:(CDVInvokedUrlCommand*)command withNoAnimate:(BOOL)noAnimate
     nav.orientationDelegate = self.inAppBrowserViewController;
     nav.navigationBarHidden = YES;
     nav.modalPresentationStyle = self.inAppBrowserViewController.modalPresentationStyle;
+    nav.presentationController.delegate = self.inAppBrowserViewController;
 
     __weak CDVWKInAppBrowser* weakSelf = self;
 
@@ -306,7 +307,6 @@ - (void)show:(CDVInvokedUrlCommand*)command withNoAnimate:(BOOL)noAnimate
                 strongSelf->tmpWindow = [[UIWindow alloc] initWithFrame:frame];
             }
             UIViewController *tmpController = [[UIViewController alloc] init];
-
             [strongSelf->tmpWindow setRootViewController:tmpController];
             [strongSelf->tmpWindow setWindowLevel:UIWindowLevelNormal];
 
@@ -1257,5 +1257,10 @@ - (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIVi
     [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];
 }
 
+#pragma mark UIAdaptivePresentationControllerDelegate
+
+- (void)presentationControllerWillDismiss:(UIPresentationController *)presentationController {
+    isExiting = TRUE;
+}
 
 @end //CDVWKInAppBrowserViewController