If you are keen to know who precisely "un-friended" you on Facebook, there is a new app now to help you in this regard.Called 'Who Deleted Me on Facebook', the iOS app lets you keep track of your friends list, The Next Web reported.Almost all of us have faced this. We look for someone who we know to be a friend of ours on Facebook and they are no longer on our list of friends.A search for them yields that they are still listed on Facebook. Did they quit us? Did they quit Facebook and then come back?Well now you can get your answer and even be updated as soon as someone un-friends you. This is a service that Facebook does not offer itself.Just as 'Who Unfollowed Me' does for Twitter, it tells you when friends have vanished from your list and whether they've deactivated their accounts or actually gotten rid of you.However, the app won't show you any past activity and it only tracks changes from the time that you activate it.