ios - Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0) with WebView SWIFT -

i'm beginner @ swift on stack overflow. first things first, have researched question online , went through related questions.the answer hoping vague (swift - exc_bad_instruction (code=exc_i386_invop, subcode=0x0) datataskwithurl) , hoping clearer answer. trying use webview display url, , keep on getting error 'thread 1: exc_bad_instruction (code=exc_i386_invop, subcode=0x0)' , 'fatal error: unexpectedly found nil while unwrapping optional value'. please me? thank you!

here code:

 import uikit    class viewcontroller: uiviewcontroller {       @iboutlet var moongatewebview: uiwebview!     @iboutlet var managebacwebview: uiwebview!     @iboutlet var moodlewebview: uiwebview!     @iboutlet var librarywebview: uiwebview!     @iboutlet var ccawebview: uiwebview!     @iboutlet var gmailwebview: uiwebview!       override func viewdidload() {         super.viewdidload()          //loading moongate on screen         let mgurl = nsurl(string: "http://moongate.cis.edu.hk/")         let mgrequest = nsurlrequest(url: mgurl!)          moongatewebview.loadrequest(mgrequest) //error occurs         //loading managebac on screen         let mburl = nsurl(string:"https://cishk.managebac.com/login" )         let mbrequest = nsurlrequest(url: mburl!)          managebacwebview.loadrequest(mbrequest)          //loading moodle on screen         let mdurl = nsurl(string: "http://moodle.cis.edu.hk/moodle/")         let mdrequest = nsurlrequest(url: mdurl!)          moodlewebview.loadrequest(mdrequest)          //loading library on screen         let liburl = nsurl(string: "http://library.cis.edu.hk/")         let librequest = nsurlrequest(url: liburl!)          librarywebview.loadrequest(librequest)          //loading ccas on screen         let ccaurl = nsurl(string: "http://moongate.cis.edu.hk/content/page.aspx?e=f17a69b3-62f1-46ff-a474-8776c2d2492d")         let ccarequest = nsurlrequest(url: ccaurl!)          ccawebview.loadrequest(ccarequest)          //loading gmail on screen         let gmailurl = nsurl(string: "https://mail.google.com/mail/u/0/")         let gmailrequest = nsurlrequest(url: gmailurl!)          gmailwebview.loadrequest(gmailrequest)       } } 

possible problem webview may nil.

to check this, need use assistant editor (where can see split view) show storyboard on 1 side , code on other.

in way can check @iboutlet correctly bound. positioning mouse on ribbon left of each of web views, highlight element bound:

if variable not bound, can see empty circle instead full circle.

you first check that, sure elements correctly bound.