未调用PFFacebookUtils logInInBackgroundWithReadPermissions块

Question

在更新xcode7之后未调用PFFacebookUtils logInInBackgroundWithReadPermissions块,并从此处解析SDK到1.8.5和Facebook SDK 4.6:https://developers.facebook.com/docs/ios/ios9

NSArray *permissions = [NSArray arrayWithObjects:@"email",@"user_friends", nil];
[PFFacebookUtils logInInBackgroundWithReadPermissions:permissions block:^(PFUser *user, NSError *error)
{
 if (!user) // The user cancelled the Facebook login
 {
     NSLog(@"Uh oh. The user cancelled the Facebook login.");
 }
 else if (user.isNew) // New user (not stored on DB) - User signed up and logged in through Facebook
 {
     [self handleNewUser];
 }
 else if (user) // the user is exist at DB
 {
   // the user is exist at DB  
 }
 else if (error)
 {
    // showAlertOfSomethingWentWrong
 }
}];

我该怎么做才能解决这个问题？