I'm experimenting with WkWebKit talking back and forth between app and page. I can get javaScript to execute fine using WkWebView evaluateJavascript method, but when I try to execute window.webkit.messageHandlers.myHandler.postMessage('hello world!') on the JavaScript page, I find that window.webkit is not defined.
Odd... I'm running in a simulator of iPad with ios 8.4. I thought this was available in original version 8, no?
I can't find anyone else posting about this, so perhaps I've done something wrong?
I've even attached my Safari Developer to the simulator's browser, and in the console I try to see what window.webkit is, and sure enough, it does not exist.
Note that I add an initial script to run when the page loads (I see this in the javascript editor - the message is logged). And I add a script message handler as well...
[EDIT: Adding more code details here] Here is my code:
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSLog(@"main view Controller viewDidLoad called...");
// if we are running on an OLD ios (pre v8) WKWebView will not exist. So don't create it if it doesn't exist...
if (NSClassFromString(@"WKWebView")) {
// WKWebView cannot be dragged onto storyboard, so have to create it manually here.
// We have a "ContainerView" called _webContainer that this browser view will live inside
// First we create a web view configuration object...
WKWebViewConfiguration *wbConfig = [WKWebViewConfiguration alloc];
wbConfig.mediaPlaybackAllowsAirPlay = true;
wbConfig.mediaPlaybackRequiresUserAction = false;
// inject some Javascript into our page before it even loads...
NSString *scriptSource = @"console.log('Hi from the iOS app hosting this page...'); window.hostedByWkWebView=true;";
WKUserScript *userScript = [[WKUserScript alloc]
initWithSource:scriptSource
injectionTime:WKUserScriptInjectionTimeAtDocumentStart
forMainFrameOnly:YES];
[wbConfig.userContentController addUserScript:userScript];
[wbConfig.userContentController addScriptMessageHandler:self name:@"myHandler"]; // javascript to use this would be: window.webkit.messageHandlers.myHandler.postMessage
// Ok, the config is created, now create the WkWebView instance, passing in this config...
_webView = [[WKWebView alloc] initWithFrame: [_webContainer bounds] configuration:wbConfig];
_webView.autoresizesSubviews = true;
_webView.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
_webView.navigationDelegate = self;
// Add the web view to the container view, and tell the container to automatically resize its subviews, height and width.
[_webContainer addSubview:_webView];
_webContainer.autoresizesSubviews = true;
_webContainer.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
// Set the URL for the webview and navigate there...
NSString *fullURL = @"https://myurlgoeshere.com";
NSURL *url = [NSURL URLWithString:fullURL];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[_webView loadRequest:requestObj];
}
else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Cannot create Web View" message:@"The web view used requires iOS 8 or higher. Sorry." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:@"", nil];
[alert show];
}
//...
I solved it and problem was that if you set userContentController
to a new object, that userContentController
's WKScriptMessageHandler
s will not be registered correctly in Apple's internal code:
WKUserContentController *userContentController = [WKUserContentController new];
userContentController.addScriptMessageHandler(self, name: "jockey")
userContentController.addScriptMessageHandler(self, name: "observe")
webView.configuration.userContentController = userContentController
fixed by using the already instantiated userContentController
by Apple:
webView.configuration.userContentController.addScriptMessageHandler(self, name: "jockey")
webView.configuration.userContentController.addScriptMessageHandler(self, name: "observe")