Fedup from fake facebook apps. Here is a simple trick to know if someone viewed your facebook profile.
You need to look to your Top friends (See the picture)
Facebook announced that the top friends are not randomly selected they depend on the following list: - Friends who sent you private msg
-Friends who liked or commented on your feeds
-Friends how visited your profile
-Friends you visited their profiles (But those friends are showed in the little box in the top of your Facebook Timeline)
If a friend appears in your Top friends and you did not interacted with him/her (private msg, likes, comments, ...) this means that he/she visted your profile.