Failed to read values in CFPrefsPlistSource iOS 10 - ios

Question

I've updated my Xcode 8 to beta 2 today and I'm trying to share data between App and Today Extension. I'm facing with this log warning:
2016-07-08 18:00:24.732472 ProjetctX[941:42801] [User Defaults] Failed
to read values in CFPrefsPlistSource<0x1700f1280> (Domain:
group.x.p.t.o, User: kCFPreferencesAnyUser, ByHost: Yes, Container:
(null)): Using kCFPreferencesAnyUser with a container is only allowed
for System Containers, detaching from cfprefsd
Anyone can help me?

Answer 1

This is actually a spurious warning that was introduced in iOS 10 and macOS 10.12:
NSUserDefaults tip: in the current OSs there's a logged error "…with a container is only allowed for System Containers…".
This is spurious.
Trying to catch a particular failure mode, caught a normal operation case at the same time.
My successor on UserDefaults also has not figured out a way to make this less alarming without making the symptomatic case impossible to debug :/
https://twitter.com/Catfish_Man/status/784460565972332544 [thread]
The advice of prepending your team ID will silence the warning, but will also create a new empty user defaults. This will result in any previously stored data being unreadable.
For the time being, the solution is just to ignore it.
Also, Apple staff member CFM on the forums:
The logged message is spurious unless you're doing very specific things that I don't think are possible without using private functions (it was added to catch misuse of those functions, but unfortunately also caught a normal usage case).

Answer 2

Here’s how to use UserDefaults with App Groups to pass data between your main app and your extension:
In your main app, select your project in the Project Navigator.
Select your main app target and choose the Capabilities tab.
Toggle the App Groups switch to ON. This will communicate with the
Developer Portal in order to generate a set of entitlements.
Create a new container. According to Apple, your container ID must
start with "group", so a name such as "group.io.intrepid.myapp" is
perfect.
Select your extension target and repeat the process of enabling App
Groups. Do not create a new App Group, simply select the group that
was just created in the main app target.
When reading or writing UserDefaults in either your app or your
extension, do not access UserDefaults.standard.
Instead use UserDefaults(suiteName: "group.io.intrepid.myapp").
Note: The suite name is the name of your App Group container created
in Step 4.
Make sure, group enable and using same group id for both extension and app capability section!
Credit goes to http://blog.intrepid.io/ios-app-extensions

Answer 3

Change you group name in Xcode entitlements from:
group.com.mycompany.myapp
To
group.MYTEAMID.com.mycompany.myapp
ps: you can find your MYTEAMID in developer.apple.com membership

Answer 4

The solution for me was to not use the same identifier for the application Bundle Identifier and the part after "group.".
Say, the app bundle id is "com.app.id", then group id as "group.com.app.id" is causing issues. After I change it to "group.com.app.id.something" it stops.

Answer 5

Also had same issue with my macOS app.
Solved it by: Reboot the device!
https://stackoverflow.com/a/39876271

Answer 6

The SuiteName (postfix) must not be the main Bundle ID.

Answer 7

I’m facing this same issue when I’m trying to use initWithSuiteName. Seems that this is a bug from Apple.
The only solution / workaround I found is to reset all the settings of the device.
Go to Settings -> General -> Reset -> Reset All Settings.
This doesn’t erase any content on the iPhone, just erases all the settings.
After resetting the setting, everything worked fine. Let me know if it helps you too.

Answer 8

Build with Xcode 8.1 Beta and you will see the same warning, but you will also get the value.

Answer 9

By default, if you are using the Settings.Bundle/Root.plist for displaying and editing your app preferences via Apple Settings App, it uses the UserDefaults.standard dictionary.
So if you are using App-Groups and you want to share this defaults / settings within your apps and extension, you need to change the container of your settings.
Step 1: Open your Settings.Bundle -> Root.plist
Step2: Add the key ApplicationGroupContainerIdentifier and as value set your App-Group-Id, defined in your Signing & Capabilities: Looks like group.xx.yy
After you have implemented this step, the default container for your App-Settings will now switch from UserDefaults.standard (your apps Path) to the Shared Path.

Answer 10

Set by example
NSUserDefaults *userDefaults = [[NSUserDefaults alloc] initWithSuiteName:#"group.com.xxx.xxx"];
[userDefaults setValue:#"value" forKey:#"key"]
[userDefaults synchronize]; // return maybe false, but it doesn't matter
Get by
NSUserDefaults *userDefaults = [[NSUserDefaults alloc] init];
[userDefaults addSuiteNamed:#"group.com.xxx.xxx"];
NSString *value = [useDefaults valueForKey:#"key"];
Although the same error will still be printed when setting, the value is indeed set and can be read correctly. But I don't know why this is happening, it's just the result of various attempts.

Answer 11

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"];
http://www.jianshu.com/p/e782104c3bc3

Answer 12

Change from
[[NSUserDefaults alloc] initWithSuiteName:#"group.com.xxx.xxx"];
to
[[NSUserDefaults alloc] initWithSuiteName:#"nnnnnnnnnn.group.com.xxx.xxx"];
Where nnnnnnnnn is your team number, the one which you use to sign your code.
Tested under Xcode 8 GM and iOS 10 GM, and worked!