NSUserDefaults not loading for Today Extension (Swift)

Question

I'm trying to make a Today Extension, and in the main app favorite is being correctly written and read from both ar and ar2. favorite is a property of class Book. However, when I try to access the favorite property of an array of all Book objects from the Today Extension, both ar and ar2 are empty.

main app:

var favorite: Bool {
        get {
            let ar = NSUserDefaults.standardUserDefaults().stringArrayForKey("favorites") ?? []
            let ar2 = NSUserDefaults(suiteName: "group.com.TodayExtension")
            ar2?.synchronize()
            let tempVar = ar2?.stringArrayForKey("favorites") ?? []
            print("ar1: \(ar)")
            print("tempVar: \(tempVar)")
            return ar.contains {
                $0 == slug
            }
        }

        set {
            var ar = NSUserDefaults.standardUserDefaults().stringArrayForKey("favorites") ?? []
            let ar2 = NSUserDefaults(suiteName: "group.com.TodayExtension")
            let contains = self.favorite
            if (newValue && !contains) {
                ar.append(self.slug)
                ar2?.setObject(ar, forKey: "favorites")
                ar2?.synchronize()
            } else if (!newValue && contains) {
                let idx = ar.indexOf {
                    $0 == slug
                }

                if let idx = idx {
                    ar.removeAtIndex(idx)
                }
            }

            NSUserDefaults.standardUserDefaults().setObject(ar, forKey: "favorites");
        }
    }

Output:

ar1: ["Harry Potter", "Compound", "Nefarious"]
tempVar: ["Harry Potter", "Compound", "Nefarious"]

Today Extension:

func loadData(force: Bool, completion:(() -> Void)?) {
        DATA.fetchEateries(force) { (error) -> (Void) in
            dispatch_async(dispatch_get_main_queue(), {() -> Void in
                if let completionBlock = completion {
                    completionBlock()
                }

                self.books = self.DATA.books

                if self.books != [] {
                    for book in self.books {
                        if book.favorite {
                            print("I like it!")
                        } else {
                            print("I don't like \(book.name)")
                        }
                    }
                }
                else {
                    print("there are no books")
                }
            })
        }
    }

Output:

ar1: []
tempVar: []
I don't like Harry Potter
ar1: []
tempVar: []
I don't like Compound
ar1: []
tempVar: []
I don't like Nefarious

Answer 1

standardUserDefaults doesn't return the same user defaults for both target. You must create app group and then use NSUserDefaults(suiteName: "group")