Why doesn't NSUserDefaults work between my app & share extension?

Question

I have an iOS app with a share extension. I am trying to share data between them using NSUserDefaults and App Groups but, while I can write into the NSUD object, read it, an

Answer 1

Not sure if defaults.addSuite(named: ...) does the same as UserDefaults(suiteName: ...). In my app I use appGroups this way and it works as expected:

// write
if let userDefaults = UserDefaults(suiteName: appGroupName) {
    userDefaults.set("---" as AnyObject, forKey: "distance")
    userDefaults.set("---" as AnyObject, forKey: "altitude")
    ...
    userDefaults.synchronize()
}

// read
if let userDefaults = UserDefaults(suiteName: appGroupName) {
    self.distanceLabel.text = userDefaults.string(forKey: "distance")
    self.altitudeLabel.text = userDefaults.string(forKey: "altitude")
}