Saving a login and a password to the iOS keychain

gistfile1.m

- (void)setCredentialsFromKeychain {
	NSMutableDictionary *query = [NSMutableDictionary dictionary];
	NSDictionary *result = nil;

	[query setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
	[query setObject:kLCSessionManagerKeychainSubscriptionServiceKey forKey:(id)kSecAttrService];
	[query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnAttributes];
	[query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];

	if (SecItemCopyMatching((CFDictionaryRef)query, (CFTypeRef *)&result) == errSecSuccess) {
		self.username = [result objectForKey:(id)kSecAttrAccount];
		self.password = [[[NSString alloc] initWithData:[result objectForKey:(id)kSecValueData] encoding:NSUTF8StringEncoding] autorelease];
		NSLog(@"Got credentials from keychain: %@ / %@", self.username, self.password);
	}
}

- (void)_saveCredentialsToKeychain {
	NSMutableDictionary *query = [NSMutableDictionary dictionary];

	[query setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
	[query setObject:kLCSessionManagerKeychainSubscriptionServiceKey forKey:(id)kSecAttrService];

	if (self.username == nil || self.password == nil) {
		self.username = nil;
		self.password = nil;

		if (SecItemCopyMatching((CFDictionaryRef)query, NULL) == errSecSuccess) {
			NSLog(@"Removing credentials from keychain");
			OSStatus deleteStatus = SecItemDelete((CFDictionaryRef)query);
			NSLog(@"Result: %d", deleteStatus);
		} else {
			NSLog(@"No credentials to remove from keychain");
		}
	} else {
		NSMutableDictionary *credentials = [NSMutableDictionary dictionary];

		[credentials setObject:(id)self.username forKey:(id)kSecAttrAccount];
		[credentials setObject:(id)[self.password dataUsingEncoding:NSUTF8StringEncoding] forKey:(id)kSecValueData];

		if (SecItemCopyMatching((CFDictionaryRef)query, NULL) == errSecSuccess) {
			NSLog(@"Updating credentials in keychain to: %@ / %@", self.username, self.password);
			OSStatus updateStatus = SecItemUpdate((CFDictionaryRef)query, (CFDictionaryRef)credentials);
			NSLog(@"Result: %d", updateStatus);
		} else {
			[credentials setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
			[credentials setObject:kLCSessionManagerKeychainSubscriptionServiceKey forKey:(id)kSecAttrService];

			NSLog(@"Saving credentials to keychain: %@ / %@", self.username, self.password);
			OSStatus addStatus = SecItemAdd((CFDictionaryRef)credentials, NULL);
			NSLog(@"Result: %d", addStatus);
		}
	}
}