问题
Previous versions of iOS Facebook SDK (3.12) has allowed to specify loginBehavior property at FBLoginView to use system account: https://developers.facebook.com/docs/reference/ios/3.12/class/FBLoginView/
How can I implement same behavior (use FBSessionLoginBehaviorUseSystemAccountIfPresent) in latest version of SDK?
回答1:
Which version of the SDK are you having problems with. All the v3.x versions of the SDKs provide that loginBehavior property like you mentioned. In v4.0 of the SDK (released March 25), the FBLoginView is replaced by FBSDKLoginButton and still offers a loginBehavior property.
来源：https://stackoverflow.com/questions/29205414/how-to-make-fbloginview-use-system-account-by-default