NSURLSession POST request return HTML webpage code - html

Question

I am trying to submit user input to a webpage and then retrieve returned data. This webpage takes a person's name and returns his/her information from a database. I tried to make a POST request when user clicks a button then send user's input to that webpage. But when I print out returned data, it's just the html source code of that webpage, only without javaScript. How can I change/add the below function to get the person's information page? I've spent lots of time but still can't figure it out. Please help me! Thank you!
-(void) sendHTTPPost{
NSString* input = nameTextField.text;
//1
NSMutableURLRequest *req = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:#"http://find.pitt.edu"]];
[req setHTTPMethod:#"POST"];
//2
NSData* postData = [input dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
//3
NSString *postLength = [NSString stringWithFormat:#"%lu",(unsigned long)[postData length]];
[req setValue:postLength forHTTPHeaderField:#"Content-Length"];
[req setValue:#"text/html" forHTTPHeaderField:#"Content-type"];
[req setHTTPBody:postData];
//4
NSURLSession *session = [NSURLSession sharedSession];
//5
NSURLSessionDataTask *task = [session dataTaskWithRequest:req
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
// Do something with response data here - convert to JSON, check if error exists, etc....
if(error != nil){
NSLog(#"error: %#", error);
}
else{
NSString* str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"%#", str);
NSLog(#"response = %#", response);
}
}];
[task resume];
}

Answer 1

It is unlikely that the POST body is supposed to contain only the value. Chances are, it should contain
key=value&key2=value2&key3=value3...
where key is the name of the input, and value is the value of that input, in a URL-encoded format. (See "Encoding URL Data" in URL Session Programming Guide for details on how to URL-encode the values.)