Question

I have the following method that I use to create a NSMutableURLRequest with custom post data contained within a NSMutableDictionary.

+ (NSMutableURLRequest *)createURLRequestWithURL:(NSString *)URL andPostData:(NSMutableDictionary *)postDictionary {
    NSMutableURLRequest *urlRequest = [[NSMutableURLRequest alloc]init];
    NSString *postString = @"";
    NSString *postLength = nil;
    NSData *postData = nil;

    //convert post distionary into a string
    if (postDictionary) {
        for (NSString *key in postDictionary) {
            if ([postString length] != 0) {
                postString = [postString stringByAppendingString:@"&"];
            }

            postString = [postString stringByAppendingFormat:@"%@=%@", [self urlEncodeString:key], [self urlEncodeString:[postDictionary valueForKey:key]]];
        }
    }

    //get length of post and convert post into a data object
    postLength = [NSString stringWithFormat:@"%d", [postString length]];
    postData = [postString dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

    //setup the request
    [urlRequest setURL:[NSURL URLWithString:URL]];
    [urlRequest setHTTPMethod:@"POST"];
    [urlRequest setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [urlRequest setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    [urlRequest setHTTPBody:postData];

    return urlRequest;
}

Up until this point I’ve been using only string data as the values in the postDictionary.

My question is how should I modify this code to send other kinds values? Specifically I’m trying to send images to the server.

Answer 1

Used the info from the other answers to modify my code as needed:

+ (NSMutableURLRequest *)createURLRequestWithURL:(NSString *)URL andPostData:(NSMutableDictionary *)postDictionary {
    NSMutableURLRequest *urlRequest = [[NSMutableURLRequest alloc]init];
    NSMutableData *postData = [NSMutableData data];

    NSString *boundary = @"---------------------------14737809831466499882746641449";

    //convert post distionary into a string
    if (postDictionary) {
        for (NSString *key in postDictionary) {
            [postData appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];

            id postValue = [postDictionary valueForKey:key];

            if ([postValue isKindOfClass:[NSString class]]) {
                [postData appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name= \"%@\"\r\n\r\n", key] dataUsingEncoding:NSUTF8StringEncoding]];
                [postData appendData:[postValue dataUsingEncoding:NSUTF8StringEncoding]];
            } else if ([postValue isKindOfClass:[UIImage class]]) {
                [postData appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"; filename=\"%@.png\"\r\n", key, [TSGUIDCreator generateGUID]] dataUsingEncoding:NSUTF8StringEncoding]];
                [postData appendData:[@"Content-Type: image/jpeg\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
                [postData appendData:[@"Content-Transfer-Encoding: binary\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
                [postData appendData:UIImagePNGRepresentation(postValue)];
            } else {
                [NSException raise:@"Invalid Post Value" format:@"Received invalid post value while trying to create URL Request. Post values are required to be strings. The value for the following key was not a string: %@.", key];
            }
        }

        [postData appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    }

    //setup the request
    [urlRequest setURL:[NSURL URLWithString:URL]];
    [urlRequest setHTTPMethod:@"POST"];
    [urlRequest setValue:[NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary] forHTTPHeaderField:@"Content-Type"];
    [urlRequest setHTTPBody:postData];

    return urlRequest;
}