Street address verification - objective-c

Question

My user enters a recipients address (Street address not email). I need to verify it with the USPS so I know that it is actually an address.
I am digging through their API right now and I think I understand it but I'm not exactly sure how to go about it with objective-c.
So pretty much it works like so:
I have to create an XML request that contains the recipient name, address, and zip code.
I have to post that to their server
They respond with an XML response
Here is an example of what one of their constructed XML request looks like:
http://SERVERNAME/ShippingAPITest.dll?API=Verify&XML=<AddressValidateRequest% 20USERID="xxxxxxx"><Address ID="0"><Address1></Address1>
<Address2>6406 Ivy Lane</Address2><City>Greenbelt</City><State>MD</State> <Zip5></Zip5><Zip4></Zip4></Address></AddressValidateRequest>
A bit garbled but broken down:
http://SERVERNAME/ShippingAPITest.dll?API=Verify&XML=
<AddressValidateRequest% 20USERID="xxxxxxx">
<Address ID="0">
<Address1></Address1>
<Address2>6406 Ivy Lane</Address2>
<City>Greenbelt</City>
<State>MD</State>
<Zip5></Zip5>
<Zip4></Zip4>
</Address>
</AddressValidateRequest>
My first idea seems obvious but there maybe a better way to go about it. Since the XML feed short, should I go about construction by simple doing something along the lines of:
NSString *request = [NSString stringWithFormat:#"......"]
Where it is filled in and formatted along the lines posted above.
The second question is how to go about correctly sending this to the server?
I simply create a NSURL request and with the URL as the constructed XML string?
Here what I have but I keep getting that the URL was constructed wrong:
- (void)verifyAddress:(Recipient*)_recipient {
NSURL *_url = [NSURL URLWithString:#"http://testing.shippingapis.com/ShippingAPITest.dll?API=Verify&XML=<AddressValidateRequest%20USERID=\"********\"><Address ID=\"0\"><Address1></Address1><Address2>6406 Ivy Lane</Address2><City>Greenbelt</City><State>MD</State><Zip5></Zip5><Zip4></Zip4></Address></AddressValidateRequest>"];
// Create the request.
NSURLRequest *theRequest=[NSURLRequest requestWithURL:_url
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
// create the connection with the request
// and start loading the data
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (theConnection) {
// Create the NSMutableData to hold the received data.
// receivedData is an instance variable declared elsewhere.
receivedData = [NSMutableData data];
NSString* newStr = [[NSString alloc] initWithData:receivedData
encoding:NSUTF8StringEncoding];
NSLog(#"the response '%#'", newStr);
} else {
// Inform the user that the connection failed.
NSLog(#"error");
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
// This method is called when the server has determined that it
// has enough information to create the NSURLResponse.
// It can be called multiple times, for example in the case of a
// redirect, so each time we reset the data.
// receivedData is an instance variable declared elsewhere.
[receivedData setLength:0];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// Append the new data to receivedData.
// receivedData is an instance variable declared elsewhere.
[receivedData appendData:data];
}
- (void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error
{
// inform the user
NSLog(#"Connection failed! Error - %# %#",
[error localizedDescription],
[[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSString* newStr = [[NSString alloc] initWithData:receivedData
encoding:NSUTF8StringEncoding];
NSLog(#"the response '%#'", newStr);
// do something with the data
// receivedData is declared as a method instance elsewhere
NSLog(#"Succeeded! Received %d bytes of data",[receivedData length]);
}
I get the following error:
Connection failed! Error - bad URL (null)
My only question now is, am I doing everything ok as far as NSURLConnection goes? I can play around with the URL, I just want to make sure my implementation is ok so Im not running around in circles. :P

Answer 1

You have % 20 in your URL. It should be %20 (no space).
There may be other problems, but that was one was easy to spot. If you are getting an error message, you need to edit your question and paste in the exact error message.
Also, you might consider using Apple's NSURLRequest and NSURLConnection classes, because more people are likely to be familiar with them so it may be easier for you to find help.

Answer 2

Cory, I work in the address validation industry (for SmartyStreets, where what you're trying to do is our specialty in fact) and have seen a lot of similar issues to yours.
We actually used to support an XML-endpoint for our address verification API (LiveAddress). Last year we deprecated it and deployed a new JSON format because the XML was clunky to use and had a lot of problems when it's actually just a simple task (for you, the developer).
So a few things to keep in mind... and while Rob's answer is programmatically comprehensive, these are important to consider also:
The USPS is the official source of addresses for the USA, but its core domain is not providing API service. Especially with recent financial troubles, I suspect that support and maintenance of the API will wane over time.
The License Agreement for the API you're using is quite restrictive. For example:
User agrees to use the USPS Web site, APIs and USPS data to facilitate USPS shipping transactions only. [27 Jan 2012]
Meaning, if you're shipping mail or packages via the USPS by using their API, it's fine, but for any other purpose it's not allowed and it violates the TOS.
I see you're developing for iOS. There's a great JSON library for that called TouchJSON that, in my opinion, is easier to use than XML formats in Objective-C.
While the USPS service does work, they CASS-certify private entities to provide their data at a better value (more specialty, experience, features, etc).
These and other maladies can be remedied by service from a third-party vendor. More details and reasons are documented here. Which provider you choose is up to you, but I'll be happy to personally answer any other address-validation-related questions.