Sharing data between an iOS 8 share extension and main app

You should use NSUserDefaults like this:

Save data:

objc

NSUserDefaults *shared = [[NSUserDefaults alloc] initWithSuiteName:@"group.yougroup"];
[shared setObject:object forKey:@"yourkey"];
[shared synchronize];

swift

let defaults = UserDefaults(suiteName: "group.yourgroup")
defaults?.set(5.9, forKey: "yourKey")

Read data:

objc

NSUserDefaults *shared = [[NSUserDefaults alloc] initWithSuiteName:@"group.yougroup"];
id value = [shared valueForKey:@"yourkey"];
NSLog(@"%@",value);

swift

let defaults = UserDefaults(suiteName: "group.yourgroup")
let x = defaults?.double(forKey: "yourKey")
print(x)

This will work fine!

Here is how I did it:

1. Open your main app target > Capabilities > App Groups set to on
2. Add a new app group and make sure it is ticked (e.g. group.com.seligmanventures.LightAlarmFree)
3. Open your watch target (the one with Capabilities tab) > App Groups set to on
4. Add a new app group and make sure it is ticked (e.g. group.com.seligmanventures.LightAlarmFree - but must be the same name as group above)

5. Save data to the group as follows:

   var defaults = NSUserDefaults(suiteName: "group.com.seligmanventures.LightAlarmFree")
   defaults?.setObject("It worked!", forKey: "alarmTime")
   defaults?.synchronize()
   

6. Retrieve data from the group as follows:

   var defaults = NSUserDefaults(suiteName: "group.com.seligmanventures.LightAlarmFree") 
   defaults?.synchronize()
   
   // Check for null value before setting
   if let restoredValue = defaults!.stringForKey("alarmTime") {
       myLabel.setText(restoredValue)
   }
   else {
       myLabel.setText("Cannot find value")
   }
   

If you have

group.yourappgroup

use

var defaults = NSUserDefaults(suiteName: "yourappgroup")

This works for me

So apparently it works, only when the group name is used as the suite name for NSUserDefaults.

The documentation says NSUserDefaults.standartUserDefaults() should also work but it does not, and this is probably a bug.

In my scenario I'm sharing data between the parent iOS app and WatchKit. I'm using Xcode 6.3.1, iOS Deployment Target 8.3

var defaults = NSUserDefaults(suiteName: "group.yourappgroup.example")

In your viewDidLoad make sure you synchronize:

    override func viewDidLoad() {
    super.viewDidLoad()

    defaults?.synchronize()

}

Example of a button sending text but of course you can pass whatever:

 @IBAction func btnSend(sender: UIButton) {
    var aNumber : Int = 0;
    aNumber = aNumber + 1

    //Pass anything with this line
    defaults?.setObject("\(aNumber)", forKey: "userKey")
    defaults?.synchronize()

}

Then on the other side make sure app group matches:

 var defaults = NSUserDefaults(suiteName: "group.yourappgroup.example")

Then synchronize and cal: (In this case "lblNumber" is an IBOutlet label)

defaults?.synchronize()
var tempVar = defaults!.stringForKey("userKey")!;
lblNumber.setText(tempVar);

Then if you wanted to set something on this side and sync it back then just do the same thing and synchronize and just make sure the stringForKey that you call on the other side is the same:

defaults?.setObject("sending sample text", forKey: "sampleKey")
defaults?.synchronize()

Hope this makes sense