Xcode log show the above error while running in Xcode 8.1, ios 10.1. Is there any problem or should I ignore and continue?
I have this problem, too. It seems to be caused by an the Facebook SDK's Login Access Token. It caches just fine on a real device, but not on the simulators. Try running the app from a physical device.
You can ignore this warning, it's hard coded in the FacebookSDK when using the iOS Simulator. The SDK does contain a bug though which prevents the simulator from caching the access token.
You can fix this by adding the following line:
key = [NSString stringWithFormat:@"%@_fix", key];
in FBSDKKeychainStore.m:94 and FBSDKKeychainStore.m:135 just before:
[[NSUserDefaults standardUserDefaults] setObject:value forKey:key];
I had the same problem.
I tried to run in real device and this show error with OAuth Login
Then I just turn OAuth Login on and everything works well
来源：https://stackoverflow.com/questions/41033776/falling-back-to-loading-access-token-from-nsuserdefaults-because-of-simulator-bu