How to call a native Objective-C method from javascript function in a local HTML5 file and vice-versa using native Objective-C method?

Question

I want to call a JavaScript function like:

- (void)alertMe:(NSString *)msg {
[[[UIAlertView alloc] initWithTitle:@"Alert" message:msg delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil] show];
}

and

function alertMe(msg) {
alert(msg);
}

How can I call it using XCode if the HTML file is loaded on a UIWebView in XCode

Answer 1

Use the delegate method UIWebView

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType

implement query string for your javascript function

Answer 2

You can use EasyJSWebView to easily implement calling Native Objective-C method from JavaScript . The more convenient way is to implement a class that holds all your methods that your JS will call and instantiate that class with your UIWebView Control Object subclass with EasyJSWebView as an argument.

For example: I created a class JSInterface to hold all my native Obj-C methods

I have a custom method

- (void)initializeJSInterfaceForWebView:(EasyJSWebView *)webView {
    self.jsInterface.appDelegate = appDelegate;
    self.jsInterface.webView.delegate = self;
    [webView addJavascriptInterfaces:self.jsInterface WithName:@"nativeInterface"];
}

that will initialized EasyJSWebView .

I instantiate

self.jsInterface = [JSInterface initWithView:self];
[self initializeJSInterfaceForWebView:self.webView];

For instance, we have a native Objective-C method:

- (void) printLog:(NSString *)msg {
    NSLog(@"%@", msg);
}

To call on the native method from JavaScript using the nativeInterface object name as follows:

nativeInterface.printLog("This is only a test.");

Answer 3

You may want to implement query string for your JavaScript function ei:

function getQueryString(){ 
var mySearch = window.location.search.substr(1).split("&");

     if (mySearch!="") 
     {
          for(var x=0;x<mySearch.length;x++) {
                // loop to all your query string here
          }

     }
}//end function

Or you may also want to use the method

[webView stringByEvaluatingJavaScriptFromString:(NSString*)]

where you may call you local javascript like:

[webView stringByEvaluatingJavaScriptFromString:@"javascript:myJSFunction()"];

Bu this method can only be called within the webViewDidFinishLoad:(UIWebView *)webView and/or when called within webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType method the return must be NO .