user credential persistence in iPhone - iphone

Question

Since i'm new to iPhone programming, I want to do something like that: In the main screen of my app, i ask for username and password and authorize user using these info calling .net web service. In this main screen, there is a switch controller "Remember me" so that app will remember the user next time he run the app. My questions are:
1. how can i call .net web services in iPhone?
2. how can i persist these username and password information (like cookie in web app), so that user will not be asked for credential info?
i would really appreciate, thanks.

Answer 1

Persisting user credentials
If you are storing a username and password you should use the Keychain. Using the Keychain on iPhone is analogous to Keychain on the Mac.
To use Keychain import "Security/Security.h".
Apple has an example here of adding and retrieving a username and password in their documentation. The example methods
- (void)mySetObject:(id)inObject forKey:(id)key;
- (id)myObjectForKey:(id)key;
- (void)resetKeychainItem;
will enable you to persist and retrieve your user credentials almost without modifying the example code.
Calling webservices that require authentication
Depending on you authentication scheme you can either
provide username and password directly as parameters in the URL using NSURLConnection
provide a didReceiveAuthenticationChallenge method in your NSURLConnection delegate if your webservice use the "Basic Authentication" scheme

Answer 2

you use nsmutableurlrequest to generate a web services request
use nsuserdefaults to persist the username and password
Here's an example of the first:
-(void)sendUpdate {
User *user = [User sharedManager];
NSData *parkedLocation = [[NSString stringWithFormat:#"<location><latitude>%f</latitude><longitude>%f</longitude><userid>%#</userid><udid>%#</udid></location>",
coordinate.latitude, coordinate.longitude, userid, user.udid] dataUsingEncoding:NSASCIIStringEncoding];
//NSLog("parkedlocation = %#", parkedLocation);
NSString *URLstr = LOCATIONS_URL;
if (controller.put_url)
URLstr = controller.put_url;
NSURL *theURL = [NSURL URLWithString:URLstr];
//NSURLRequest *theRequest = [NSURLRequest requestWithURL:theURL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0];
NSLog(#"IN SEND UPDATE put_url = %#", controller.put_url);
NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:theURL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0];
if (controller.put_url) {
[theRequest setHTTPMethod:#"PUT"];
} else {
[theRequest setHTTPMethod:#"POST"];
}
[theRequest setValue:#"text/xml" forHTTPHeaderField:#"Content-type"];
[theRequest setHTTPBody:parkedLocation];
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:TRUE];
NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (!theConnection) {
NSLog(#"COuldn't get a connection to the iParkNow! server");
}
}
and an example of the second:
[[NSUserDefaults standardUserDefaults] setObject:self.userName.text forKey:#"Username"];
[[NSUserDefaults standardUserDefaults] setObject:self.password.text forKey:#"Password"];

Answer 3

You have two choices: User Preferences or Core Data. Both are capable - Core Data might be overkill.

Answer 4

NSURLRequest can be used to retrieve URLs such as your authentication service. And NsUserDefaults can be used to save settings in between app invocations.
Note: Check out ennuikiller's awesome example.