#About DDEnhancedJSBridge is an easy-to-use Javascript-ObjC bridge for IOS and OSX partly based on the ideas of the JSBridge project.

It is platform neutral and uses the same ObjC Code and also the same JS Code for IOS and OSX.

DDEnhancedJSBridge comes as a workspace that includes a project for building the bridge as a static library and also includes demo projects for the two platforms that in large parts share the same source code.

Bridging works by converting the parameters to-and-from JSON. Supported are therefory all datatypes that can be expressed as JSON. (On the javascript side, there is a special case for elements. They are transparently converted to base64 data)

#####014-01-11 added DDJsonFromWeb (lightweight version!) This is for when you only need to get data from the webview but dont really have to interact with it

##Usage

###bridge from Javascript to Objective-C To enable the bridge, you:

1. You got to replace the (UI)WebView class for the DDBridgableWebView. (The class is a drop in replacement that keeps all delegate methods intact and has the same behaviour as before.)
   
   Under IOS this class catches redirects using the ddbridge url scheme. Under OSX, it inserts itself as custom object into the Javascript Context of the html page.
   The DDBridgableWebView is responsible for intercepting the Javascript and notifies the DDEnhancedJSBridge class of any requests

2. You have to register all your bridgable WebViews and receiving Objects so the bridge knows what to bridge where. E.G. for IOS you'd do it in viewDidLoad. In OSX maybe in awakeFromNib?

        - (void)viewDidLoad
        {
            [super viewDidLoad];
   
            //register everybody
            [[DDEnhancedJSBridge defaultBridge] addWebView:self.webView];
            [[DDEnhancedJSBridge defaultBridge] addObject:self.imagefilter forName:@"imagefilter"];
        }
   

3. Add the DDBridge.js javascript files to your app's build phase
   !Make sure it isn't added to the sources instead -- xcode 4 and 5 all want to compile JS, not copy i t

4. Write your javascript to use the bridge. To send a Command you create a new instance of the DDBridge object in javascript. E.G.

        function processImage(imgId)
        {
            var obj = new DDBridgeObj();
            obj.addObject("data", document.getElementById(imgId));
            obj.addObject("callback", "applyResultImage");
            
            obj.sendBridgeObject("imagefilter", "setMaskImage");
        }
   

5. Now the last step to actually have the object expose the called selector. In this case setMaskImage. To expose selectors all you have to do is follow a convention. selectors therefore need to have the following signature:
   - (void)%name%:(NSDictionary*)params bridgedFrom:(id<DDBridgableWebView*)webview
   
   so in our example:
   

    @interface DDImageFilter : NSObject<DDBridgableObject>
    
    //exposed to the web
    - (void)setImage:(NSDictionary*)params bridgedFrom:(id<DDBridgableWebView>)webview;
    - (void)setMaskImage:(NSDictionary*)params bridgedFrom:(id<DDBridgableWebView>)webview;
    
    @end
   

#####The image filter is now registered and reachable from Javascript.

##vice-versa: from Objective-C to javascript

this direction is rather trivial as you can already just call JS via the framework. but to provide a seamless API and some additional convenience I wrapped that in a method:

///sends JSON to the specified webview by calling a JSMethod
- (void)bridgeFromNative:(id<DDBridgableObject>)o toWebview:(id<DDBridgableWebView>)wv userInfo:(NSDictionary*)userInfo;

When calling this on the bridge to make a JS Call the userInfo dictionary MUST contain a param named 'method' that specifies the javascript function to call.

the js function must have the signature:
%name%(parametersJSONDictionary, senderName)

senderName specifies the name of the object as it was registered with the bridge.

#####A typical idiom is that the exposed object answers from within its exposed selector To answer from to a call bridged FROM JS, call the above method like in this example:

- (void)setMaskImage:(NSDictionary*)params bridgedFrom:(id<DDBridgableWebView>)webview {
    _imageMask = [[DDImage alloc] initWithData:[NSData dataFromBase64String:params[@"data"]]];
    [self buildResultAndDeliverTo:webview as:params[@"callback"]];
}

- (void)buildResultAndDeliverTo:(id<DDBridgableWebView>)wv as:(NSString*)cb {
    ...    
    NSMutableDictionary *dict = @{@"data" : @"", @"method" : cb}.mutableCopy;
    ...     

    if([_bridge canBridgeFromNative:self toWebview:wv userInfo:dict]) {
        [_bridge bridgeFromNative:self toWebview:wv userInfo:dict];
    }
}

###AVAIABLE under MIT