I am developing a web app that is being displayed in a UIWebView. The app is loaded locally, i.e, not from a web server. I am communicating from Javascript to ObjC via the shouldStartLoadWithRequest: method in the UIWebViewDelegate protocol.
The last thing I need is to be able to call Javascript functions from ObjC without any page reloads. I hope this is possible.
Well, you can call
-[UIWebView stringByEvaluatingJavaScriptFromString:]
whenever you like, not just in response to a delegate method.
You can call any javascript function in your webview by simply using the stringByEvaluatingJavaScriptFromString method on your webview after you've loaded the webview:
[self.myWebView stringByEvaluatingJavaScriptFromString:@"myJavaScriptFunction(123.0)"];
You don't need to reload the webview to send this message (just don't release the webview before you're done).
Could't you just do this by doing a "loadRequest", and passing it an NSURL with contents like like:
javascript:myFunction("MyParameter");
It should call your function, but not reload the page.
One can use JavaScriptCore framework to run JavaScript code from Objective-C.
#import <JavaScriptCore/JavaScriptCore.h>
...
JSContext *context = [[JSContext alloc] init];
[context evaluateScript: @"function greet(name){ return 'Hello, ' + name; }"];
JSValue *function = context[@"greet"];
JSValue* result = [function callWithArguments:@[@"World"]];
[result toString]; // -> Hello, World
Here is a demo:
