使用javascriptcore框架调用javascript函数会将[object Object]返回给JSValue

Question

Code in .js file:

var fact = function(x){
    return WeatherWebService(x);
}   

objective-c native methods:

 - (IBAction)btnOkClicked:(id)sender 
    {
        [self.aJSEngine loadJSLibrary:@"script"];    
    }

    - (void)loadJSLibrary:(NSString*)libraryName
    {
        NSString *library = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource:libraryName ofType:@"js"]  encoding:NSUTF8StringEncoding error:nil];

        NSLog(@"[JSC] loading library %@...", libraryName);
        [self runJS:library];
    }

    - (void)runJS:(NSString *)aJSString
    {
        if (!aJSString) {
            NSLog(@"[JSC] JS String is empty!");
        }
        else{
            JSContext *context = [[JSContext alloc]initWithVirtualMachine:[[JSVirtualMachine alloc]init]];
            context[@"WeatherWebService"] = ^(int x){
                NSDictionary *dict = [self callingWeatherFromJavascript];
                return dict;
            };

            [context evaluateScript:aJSString];
            JSValue *val = context[@"fact"];
            JSValue *finalResult = [val callWithArguments:@[context[@"3"]]];

        }
    }

    -(NSDictionary*)callingWeatherFromJavascript{
            NSString *urlString =  @"http://api.openweathermap.org/data/2.5/weather?q=London,uk";
            NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:urlString]];
            __block BOOL complete = NO;
            AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
            operation.responseSerializer = [AFJSONResponseSerializer serializer];

            [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

                // 3
                self.dictionary = (NSDictionary *)responseObject;
                complete=YES;
                // NSDictionary *dict = [self.dictionary objectForKey:@"main"];
                //            if ([self.delegate respondsToSelector:@selector(returnDataFromResponse:)]) {
                //                [self.delegate returnDataFromResponse:dict];
                //            }

            } failure:^(AFHTTPRequestOperation *operation, NSError *error) {

                // 4
                UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error Retrieving Weather"
                                                                    message:[error localizedDescription]
                                                                   delegate:nil
                                                          cancelButtonTitle:@"Ok"
                                                          otherButtonTitles:nil];
                complete=NO;
                [alertView show];
            }];


            // 5
            [operation start];
        while(complete == NO) {
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.1]];
        }
        return self.dictionary;
    }

In the above code, the method 'callingWeatherFromJavascript' returns NSDictionary . When i receive this value in "JSValue" in function '-(void)runJS' it returns [object Object] . Is there any way of converting this back into NSDictionary ?

Answer 1

I don't want to take credit away from vivek_ios, he answered his own question. I just want to rewrite his response so it's clearer and easier to re-use because it took me a while to find the answer in the comments.

Basically, converting JSValue to NSDictionary is simply done via JSValue.toDictionary. Something like this:

JSContext *jsContext  = [JSContext new];
[jsContext evaluateScript:[NSString stringWithContentsOfFile:myJavascriptFilePath encoding:NSUTF8StringEncoding error:nil]];
NSDictionary *result = [jsContext[@"myJavascriptFunction"] callWithArguments:@[optionalArgument]].toDictionary;

Answer 2

First covert your response object to NSData

NSData *responseData = [[NSData alloc]initWithContentsOfFile:(NSString*)responseObject encoding:NSUTF8StringEncoding error:nil];

Then create NSDictionary with JSON serialization as it looks like you are receiving JSON object from your webservice

NSDictionary *responceDictionary = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:nil];

Then you should be able to access your "main" key and get all info from here.