post HTTPRequest of NSDictionary with one NSSet as value

Question

I have a core data object with a one-to-may relation. So for instance

person.mothername
person.fathername
person.childrennames <- this is a NSSet

Now I want to post this at once from the iPhone to our server through one HTTP request. Can this be done?

The code that I use right now for a plain example without NSSet: Setting the parameters:

params = [NSDictionary dictionaryWithObjectsAndKeys:
              self.person.mothername, @"mothername",
              self.person.fathername, @"fathername",
              nil];
self.httpRequest = [[HTTPRequest alloc] init];
self.httpRequest.delegate = self;
[self.httpRequest httpPOST:SERVER_POST_PERSON withParams:params];

Then the next step (= straightforward):

- (BOOL)httpPOST:(NSString *)url withParams:(NSDictionary *)params {

const char *strUrlConst = (const char*)[[self buildParams:params] UTF8String]; 

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0];

[request setHTTPMethod:@"POST"];
[request setHTTPBody:[NSData dataWithBytes:strUrlConst length:strlen(strUrlConst)]];

NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (connection) {
    self.responseData = [[NSMutableData data] retain];
    return YES;
}

return NO;

}

Then the final method (straightforward?):

- (NSString *)buildParams:(NSDictionary *)params {
NSString *builtParams = [[[NSString alloc] init] autorelease];

int i = 0;
for (NSString *key in [params allKeys]) {
    NSString *value = [self escapeString:[params objectForKey:key]];
    if (!value) {
        continue;
    }
    if (!i++) {
        builtParams = [builtParams stringByAppendingString:[NSString stringWithFormat:@"%@=%@", key, value]];
    } else {
        builtParams = [builtParams stringByAppendingString:[NSString stringWithFormat:@"&%@=%@", key, value]];
    }
}

NSLog(@"PARAMS: %@", builtParams);
return builtParams;

}

Answer 1

You can use NSSet's -allObjects and +setWithArray: to convert it to an NSArray and back.

Answer 2

Why not use JSON?
Libraries like SBJson can create a JSON string from an NSDictionary in one line of code (IIRC: [params JSONRepresentation]). It is straightforward to URL encode it by using NSString's percent esacpes method.
On the server side there should be plenty of JSON libraries to choose from for parsing the data.