Share between an iOS extension and its containing app with the keychain?

Question

I understand I can share data between my share extension and its containing app by enabling app groups and using NSUserDefaults (see Sharing data between an iOS 8 share extensio

Answer 1

Using the standard Objective-C KeychainItemWrapper class and with an entry of #import "KeychainItemWrapper.h" in the bridging header:

    func btnSaveAction() {

    let appGroupID = "group.com.yourcompany.appid"
    let keychain = KeychainItemWrapper(identifier: "Password", accessGroup:appGroupID)
    keychain.setObject(self.txtfldPassword.text!, forKey:kSecValueData)
    keychain.setObject(self.txtfldEmail.text!, forKey:kSecAttrAccount)

    }

On the Watch extension side (Swift):

override func awakeWithContext(context: AnyObject?) {
    super.awakeWithContext(context)

    let appGroupID = "group.com.yourcompany.appid"
    let keychain = KeychainItemWrapper(identifier: "Password", accessGroup:appGroupID)
    println(keychain.objectForKey(kSecAttrAccount))
    println(keychain.objectForKey(kSecValueData))

}

In Objective C, watchkit extension:

NSString *appGroupID = @"group.com.yourcompany.appid";
KeychainItemWrapper *keychain = [[KeychainItemWrapper alloc] initWithIdentifier:@"Password" accessGroup:appGroupID];
[keychain setObject:(__bridge id)(kSecAttrAccessibleWhenUnlocked) forKey:(__bridge id)(kSecAttrAccessible)];
NSLog(@"account = %@", [keychain objectForKey:(__bridge id)(kSecAttrAccount)]);
NSLog(@"password =%@", [keychain objectForKey:(__bridge id)(kSecValueData)]);

Don't forget to turn on "Keychain Sharing" under "Capabilities" for both the phone app and watch kit extension for same keychain group: "group.com.yourcompany.appid"