Add flag for UIWebView usage (#588)

* Add flag for UIWebView usage

README.md

@@ -116,6 +116,11 @@ With the CodePush plugin installed, configure your app to use it via the followi
 
 You are now ready to use the plugin in the application code. See the [sample applications](/samples) for examples and the API documentation for more details.
 
+*NOTE: There is a possibility to specify WebView engine on the plugin build phase. By default UIWebView engine is used. You can force plugin to use WKWebView by adding this iOS specific preference:*
+```xml
+<preference name="WKWebViewOnly" value="true" />
+```
+
 ## Plugin Usage
 
 With the CodePush plugin installed and configured, the only thing left is to add the necessary code to your app to control the following policies:

src/ios/CodePush.m

@@ -401,7 +401,7 @@ - (void)loadURL:(NSURL*)url {
     // maintaining back-compat with Cordova iOS 3.9.0, we need to conditionally
     // use the WebViewEngine for performing navigations only if the host app
     // is running 4.0.0+, and fallback to directly using the WebView otherwise.
-#ifdef __CORDOVA_4_0_0
+#if (WK_WEB_VIEW_ONLY && defined(__CORDOVA_4_0_0)) || defined(__CORDOVA_4_0_0)
     [self.webViewEngine loadRequest:[NSURLRequest requestWithURL:url]];
 #else
     [(UIWebView*)self.webView loadRequest:[NSURLRequest requestWithURL:url]];

src/ios/CodePushReportingManager.m

@@ -34,6 +34,15 @@ + (void)reportStatus:(StatusReport*)statusReport withWebView:(UIView*)webView {
 
         /* JS function to call: window.codePush.reportStatus(status: number, label: String, appVersion: String, deploymentKey: String) */
         NSString* script = [NSString stringWithFormat:@"document.addEventListener(\"deviceready\", function () { window.codePush.reportStatus(%i, %@, %@, %@, %@, %@); });", (int)statusReport.status, labelParameter, appVersionParameter, deploymentKeyParameter, lastVersionLabelOrAppVersionParameter, lastVersionDeploymentKeyParameter];
+        #if WK_WEB_VIEW_ONLY
+        if ([webView respondsToSelector:@selector(evaluateJavaScript:completionHandler:)]) {
+            // The WKWebView requires JS evaluation to occur on the main
+            // thread starting with iOS11, so ensure that we dispatch to it before executing.
+            dispatch_async(dispatch_get_main_queue(), ^{
+                [webView performSelector:@selector(evaluateJavaScript:completionHandler:) withObject:script withObject: NULL];
+            });
+        }
+        #else
         if ([webView respondsToSelector:@selector(evaluateJavaScript:completionHandler:)]) {
             // The WKWebView requires JS evaluation to occur on the main
             // thread starting with iOS11, so ensure that we dispatch to it before executing.
@@ -47,6 +56,7 @@ + (void)reportStatus:(StatusReport*)statusReport withWebView:(UIView*)webView {
                 [(UIWebView*)webView stringByEvaluatingJavaScriptFromString:script];
             });
         }
+        #endif
     }
 }
 
@@ -62,7 +72,7 @@ + (BOOL)hasFailedReport {
     if (HasFailedReport == -1) {
         HasFailedReport = [self getFailedReport] != nil;
     }
-    
+
     return HasFailedReport;
 }
 
@@ -72,7 +82,7 @@ + (StatusReport*)getFailedReport {
     if (!failedReportDict) {
         return nil;
     }
-    
+
     return [[StatusReport alloc] initWithDictionary:failedReportDict];
 }