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

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, and synchronize() without error, reading in the extension always results in nil.
I have an app group, the literal string "group.net.foo.bar" for which both the app & extension have configured under Capabilities -> App Groups. This string is in a constants struct in my app:
struct Forum {
static let APP_GROUP = "group.net.foo.bar"
static let AUTH_KEY = "AUTH_KEY"
}
In the main app I create a UserDefaults object and write to it:
fileprivate lazy var userDefaults: UserDefaults = {
let defaults = UserDefaults()
defaults.addSuite(named: Forum.APP_GROUP)
return defaults
}()
// later
userDefaults.set(apiKey, forKey: Forum.AUTH_KEY)
userDefaults.synchronize()
Creating a new NSUD object after that synchronize() and retrieving the AUTH_KEY works. In the extension, I create an NSUD and try to retrieve the value, to no avail:
private lazy var userDefaults: UserDefaults = {
let defaults = UserDefaults()
defaults.addSuite(named: Forum.APP_GROUP)
return defaults
}()
// later
private func getApiKey() -> String? {
return userDefaults.string(forKey: Forum.AUTH_KEY)
}
// returns nil
In all of my reading of the Apple docs and depressingly-similar questions here on Stack Overflow I can't divine what I've done incorrectly.
Xcode Version 8.0 (8A218a), also tested with Xcode 8.1 Beta 2. Same behavior on simulator andy my iPhone 6s running iOS 10.

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")
}

Answer 2

if you suffer this problem when you try to save data to extension APP by using userDefault,maybe you had written this code : [[NSUserDefaults standardUserDefaults] initWithSuiteName:#"group.xxx.com"];,this code reset default userDefault. Actually,the correct code is : [[NSUserDefaults alloc] initWithSuiteName:#"group.xxx.com"]; enter link description here