recuperate data from form textfield in xcode 5 and ios7

Hi,

I have created a wcf service to insert data in my sql server DB.

here is the URL used :
41.142.251.142/JsonWcfService/GetEmployees.svc/json/InsertEmployee/val1/val2/val3.


so when I want to consume this web service inside my xcode 5, I used the following:

I created a form with ( firstName.text, lastName.text,address.text, and button to insert data ) 

in my ViewController.m:

I declared the webservice URL as follow :
 #define BaseWcfURL [NSURL URLWithString: @"http://41.142.251.142/JsonWcfService/GetEmployees.svc/json/InsertEmployee/{id1}/{id2}/{id3}"]

so in my button action to insert the data, I added this command to recuperate all the text fields values :

NSstring *str= [BaseWcfUrl stringByAppendFormat:@"InsertEmployee/@/@/@", firstName.text,lastName.text,address.text];


but the issue here is the str string always return Nil, and the textfield are nil as values! ????

I don't Know why, I entered the value but I cannot recuperate them ?!!