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WkWebView JavaScript script not working

My Goal is to send data from iOS device to WkWebView. After researching on how to do this task I get to know that it can be done via executing JavaScript function via WkWebView, therefore, I tried calling just a simple alert function:
#interface UIWebViewController () <WKNavigationDelegate, WKUIDelegate>
#end
WKWebView *webView;
-(void)webView:(WKWebView )webView didFinishNavigation:(WKNavigation )navigation{
NSString* javascriptString = #"alert('Hi');";
[webView evaluateJavaScript:javascriptString completionHandler:nil];
}
- (void)viewDidLoad {
[super viewDidLoad];
WKWebViewConfiguration *theConfiguration = [[WKWebViewConfiguration alloc] init];
webView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:theConfiguration];
webView.navigationDelegate = self;
}
Unfortunately I am not able to see any alert with that code?
Can you let me know what kind of silly mistake I am doing in the above code?

EasyJSWebView breaks when reloading the webview

I have been implementing EasyJSWebView into a project that pops up a web view on the receipt of a push message. This works fine for the most part, until you want to reload the current webview. At that point the functionality of EasyJSWebView breaks and the javascript in the webpage cannot communicate with the objective C running in the app.
This is the code I'm using to add the interface to the webview and then load the page on the view.
_webView.delegate = self;
javaScriptInterface* interface = [javaScriptInterface new];
[self.webView addJavascriptInterfaces:interface WithName:#"interface"];
interface.webView = self;
[interface release];
[[NSURLCache sharedURLCache] removeAllCachedResponses];
[_webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:#"mywebpage.com"]]];
If I call another loadrequest on the webview, even if it is to the same page, this stops working. I have tried adding another interface object to the webview before a reload but that doesn't seem to do anything either.
At the moment I am destroying the current webview and creating a new one each time I need to do a reload or another push message is received.
Is there any fix or workaround to this? I would like to be able to use one webview for everything and not worry if it gets reloaded or not.

There's a bug in the original EasyJSWebView repository.
Just use the fork from here: https://github.com/andiradulescu/EasyJSWebView

I'm not sure if this is the best way to solute the issue, but it works in my project. My method is to create an new UIWebView before every reload or redirect request. Below is the details:
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
//'isNotFirstLoad' marks if it is the fisrt load.
if (isNotFirstLoad) {
//create an new webview
CGRect frame = _myWebView.frame;
[_myWebView removeFromSuperview];
_myWebView = [[EasyJSWebView alloc] initWithFrame:frame];
[self.view addSubview:_myWebView];
//init the new webview
_webView.delegate = self;
javaScriptInterface* interface = [javaScriptInterface new];
[self.webView addJavascriptInterfaces:interface WithName:#"interface"];
[_myWebView loadRequest:request];
//reset the firstload flag to load the new request
isNotFirstLoad = NO;
return NO;
}
isNotFirstLoad = YES;
return YES;
}

iOS - Webview - Notify Javascript when an NSNotification is received

I was wondering if anyone knew how to do this. I have a bunch of NSNotifications and I'd like to create listeners in Javascript, embedded in a UIWebView, that will get executed when the NSNotifications are received.
I know this is possible using PhoneGap and the method sendPluginResult, but I was wondering if there was another way of doing it without cordova.
Thanks

Create your listener outside the UIWebView and send the stringByEvaluatingJavaScriptFromString message to your web view.
- (void)registerObserver
{
NSArray *names = [NSArray arrayWithObjects:
#"FirstNotification", #"SecondNotification", #"ThirdNotification", nil];
for (NSString *name in names)
{
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(notificationReceived:)
name:#"NotificationName"
object:nil];
}
}
- (void)notificationReceived:(NSNotification *notification)
{
NSString *js = [NSString stringWithFormat:
#"notificationReceived('%#');", notification.name];
[self.webView stringByEvaluatingJavaScriptFromString:js];
}

in the call back NSNotification method call this:
[yourwebview stringByEvaluatingJavaScriptFromString:#"methodName()"];
and create that "methodname" in your javascript code

Pushwoosh phonegap plugin, retrieving device ID

I'm using the pushwoosh phonegap plugin for push notifications. After successful registration I need to store the device ID that the registration used in the "hwid" parameter so that I can target push notifications that I send with this same device ID. This works great on Android since it seems the phonegap device.uuid is the same ID that the pushwoosh plugin is sending to their servers. However, on ios the device.uuid returns a different ID than what is sent to pushwoosh. I can see from the Xcode console log the hwid that the plugin is sending to pushwoosh but cannot figure out where they are getting this ID from and how to access the same ID within phonegap.
EDIT: I was hoping the getRemoveNotificationStatus function would return this info but it actually returns less than the registerDevice callback.
UPDATE: Ok, from digging through their plugin code I see where they are constructing this ID that they send to their servers. Not sure why this ID isn't accessible through the phonegap plugin since this is the ID that I ultimately need to have in order to target a push notification to the specific device.
Their code:
(NSString *) uniqueDeviceIdentifier{
NSString *macaddress = [self macaddress];
NSString *bundleIdentifier = [[NSBundle mainBundle] bundleIdentifier];
NSString *stringToHash = [NSString stringWithFormat:#"%#%#",macaddress,bundleIdentifier];
NSString *uniqueIdentifier = [self stringFromMD5:stringToHash];
return uniqueIdentifier;
}
- (NSString *) uniqueGlobalDeviceIdentifier{
// >= iOS6 return identifierForVendor
UIDevice *device = [UIDevice currentDevice];
if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(#"6.1")) {
if ([device respondsToSelector:#selector(identifierForVendor)] && [NSUUID class]) {
NSUUID *uuid = [device identifierForVendor];
return [uuid UUIDString];
}
}
// Fallback on macaddress
NSString *macaddress = [self macaddress];
NSString *uniqueIdentifier = [self stringFromMD5:macaddress];
return uniqueIdentifier;
}

Are you sure that you need the hwid?
When I use the Pushwoosh Remote API to send push messages to individual devices I target using the "devices" tag and then just supply the deviceToken of the devices I wish to message.
The device token is easily accessible as it's part of the status-return from the plugin (status['deviceToken']).

As I posted here.
I found a work-around for anyone who needs this. Just open up the class "PWRequest.m" in xcode. Add the code below just under "[dict setObject:hwid forKey:#"hwid"];" in the NSMutableDictionary method.
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingPathComponent:#"hwidfile2.txt"];
NSLog(#"From Echo Class File Path: %#", filePath);
NSString *str = hwid;
This will save a text file to your local app directory in which you can access from your Javascript code. For example, you can use this JS code to access and print the hwid to the console. Just call the 'readPwfile(filename)' function, passing in the name of your file as the function argument.
function readPWFile(fileName){
window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fileSystem){
fileSystem.root.getFile(fileName, null, gotReadFileEntry, fail);
});
function gotReadFileEntry(fileEntry) {
fileEntry.file(gotFile, fail);
}
function gotFile(file){
//readDataUrl(file);
readAsText(file);
}
function readAsText(file) {
var reader = new FileReader();
reader.onloadend = function(evt) {
console.log('Reading file... hwig Result: '+evt.target.result);
};
reader.readAsText(file);
}
}

Can I handle alert inside UIWebViewDelegate?

<script language="javascript">
alert("Hell! UIWebView!");
</script>
I can see the alert message inside my UIWebView but can I handle this situation?
Update:
I'm loading a web-page into my UIWebView:
- (void)login {
NSString *requestText = [[NSString alloc] initWithFormat: #"%#?user=%#&password=%#", DEFAULT_URL, user.name, user.password]; // YES, I'm using GET request to send password :)
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:requestText]];
[webView loadRequest:request];
}
The target page contain a JS. If user name or password is incorrect this JS show alert.
I have not any access to its sources.
I want to handle it inside my UIWebViewDelegate.

A better solution to this problem is to create a Category for UIWebView for the method
webView:runJavaScriptAlertPanelWithMessage:initiatedByFrame:
So that you can handle the alert event in any way that you'd like. I did this because I don't like the default behavior of UIWebView when it puts the filename of the source in the UIAlertView title. The Category looks something like this,
#interface UIWebView (JavaScriptAlert)
- (void)webView:(UIWebView *)sender runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WebFrame *)frame;
#end
#implementation UIWebView (JavaScriptAlert)
- (void)webView:(UIWebView *)sender runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WebFrame *)frame {
UIAlertView* dialogue = [[UIAlertView alloc] initWithTitle:nil message:message delegate:nil cancelButtonTitle:#"Okay" otherButtonTitles:nil];
[dialogue show];
[dialogue autorelease];
}
#end

This seems to do it:
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
JSContext *ctx = [webView valueForKeyPath:#"documentView.webView.mainFrame.javaScriptContext"];
ctx[#"window"][#"alert"] = ^(JSValue *message) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"JavaScript Alert" message:[message toString] delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
};
}
Note: only tested on iOS 8.

If by "contain a flash" you mean the page you're loading into your web view has an Adobe Flash movie in it, you're out of luck, I'm afraid. Mobile Safari doesn't support Flash, and most likely never will.
In the general case, if you want JavaScript running in a web view to communicate with the native app hosting it, you can load fake URLs (for example: "myapp://alert?The+text+of+the+alert+goes+here."). That will trigger the webView:shouldStartLoadWithRequest:navigationType: delegate method. In that method, inspect the request, and if the URL being loaded is one of these internal communications, trigger the appropriate action in your app, and return NO.