sms - iOS MessageUI.h not found -

I want to use an MFMessageComposeViewController to send an in-app SMS and I import messageUI frameworks in my project. But when I use

  #import "MessageUI.h"   
, I told that: MessageUI.h was not found. I do not know why and how can I fix this?  
 Thank you very much.  
   
    
 
 
 This syntax:         Use this syntax:  
  #import & lt; MessageUI / MessageUI.h>   
 When you use this syntax, the compiler knows where to look for the header in the question.