POST data in CUSTOM doc

Hello everyone… I am not able to POST my data to CUSTOM doctype in ERPNEXT…
I have created one custom doctype (Customer) having fields
postData = {‘customer_email’:‘’,‘customer_contact_number’:‘1234’,‘customer_name’:‘eee’,‘customer_address’:‘pune’}

Am trying to post data through IOS app. And I use dictionary format to send data to URL.

NSMutableURLRequest *req = nil;
self.responseData = [NSMutableData data];
NSURL *url = [NSURL URLWithString:urlString];   \\CUSTOMER DOCTYPE URL

if ([method isEqualToString:@"POST"]) {
    NSError *err;
    NSData * jsonData = [NSJSONSerialization  dataWithJSONObject:param options:0 error:&err];   \\ param is DICTIONARY having customer data
    NSString * myString = [[NSString alloc] initWithData:jsonData   encoding:NSUTF8StringEncoding];
    NSData *data = [myString dataUsingEncoding:NSUTF8StringEncoding];
    req = [[NSMutableURLRequest alloc] initWithURL:url];
    [req setHTTPBody:data];
    [req setHTTPMethod:method];

please help me out… THANKS in adv