Shared UserDefaults between app and extension not working correctly

Question

So I've been looking around and following all the steps to setup shared UserDefaults correctly but I should be missing something.

I have App Groups capability activated on both my app and my extension. Both use the same suite name ("group.TestSharedPreferences") and I write this way:

struct Preferences {
    static let shared = UserDefaults(suiteName: "group.TestSharedPreferences")!
}

On viewDidLoad:

Preferences.shared.set(1, forKey: "INT")

And to read:

Preferences.shared.integer(forKey: "INT") // Returns 1 in Container App
Preferences.shared.integer(forKey: "INT") // Returns 0 in Today Extension

Even using synchronize() just after setting "INT", the value retrieved in the extension is not the one saved in the container App. Any ideas on what might I be missing? Thank you!

Answer 1

I would recommend to dig down step by step here.

First, make sure that both the main app and the widget extension have app group capability enabled and use the same and activated (the checkmark must be set) app group name:

Main App:

Today Widget Extension:

Then make a simple test with direct set/get access. In your main app's AppDelegate.didFinishLaunchingWithOptions method (change the app group name and the keys to your needs):

if let userDefaults = UserDefaults(suiteName: "group.de.zisoft.GPS-Track") {
    userDefaults.set("test 1" as AnyObject, forKey: "key1")
    userDefaults.set("test 2" as AnyObject, forKey: "key2")
    userDefaults.synchronize()
}

In your Today Widget Extension's ViewController:

if let userDefaults = UserDefaults(suiteName: "group.de.zisoft.GPS-Track") {
    let value1 = userDefaults.string(forKey: "key1")
    let value2 = userDefaults.string(forKey: "key2")
    ...
}

If this works, the problem must be related in your Preferences singleton.