我正在尝试使用FBUserSettingsViewController，但每次我尝试关闭它时它都会崩溃。我使用以下代码来显示它:FBUserSettingsViewController*userSettings=[[FBUserSettingsViewControlleralloc]initWithNibName:nilbundle:nil];userSettings.readPermissions=@[];userSettings.publishPermissions=@[@"publish_actions"];userSettings.defaultAudience=FBSessi