fatal error on loading URL in UIWebView in swift -

i using uisplitviewcontroller display ,master , detail page in all visible mode. potrait orientation only. using expandable table view in mastervc. add view in section. if tap view, url should reflect in webview in detailvc. but, code, receiving error. not using navigation controller this. directly have connected splitviewcontroller master , detail view controller. described below. kindly me.

in detail view controller

func webviewloader()     {         println("came inside web view")         let url = "http://makeapppie.com/2014/10/28/swift-swift-using-uiwebviews-in-swift/"         let requesturl = nsurl(string:url)         let request = nsurlrequest(url: requesturl!)         webview.loadrequest(request) //fatal error while unwrapping     } 

in master view controller

func tableview(tableview: uitableview, viewforheaderinsection section: int) -> uiview? {          let headerview = uiview(frame: cgrectmake(0, 0, sidetableview.frame.size.width, 49)) //adding view section - expandable tableview         var layerline = calayer()         layerline.frame = cgrect(x: 0, y: headerview.frame.size.height, width:  headerview.frame.size.width, height: 1)         layerline.backgroundcolor = uicolor(red: 220/255, green: 220/255, blue: 220/255, alpha: 1.0).cgcolor         headerview.backgroundcolor = uicolor(red: 242/255, green: 242/255, blue: 242/255, alpha: 1.0)         headerview.tag = section          headerview.layer.addsublayer(layerline) //adding bottom border cell          let headerstring = uilabel(frame: cgrect(x: 10, y: 10, width: sidetableview.frame.size.width-10, height: 30)) uilabel         headerstring.text = sidetbldata.objectatindex(section) as! nsstring string         headerstring.font = headerstring.font.fontwithsize(15)         headerview .addsubview(headerstring)          let headertapped = uitapgesturerecognizer (target: self, action: "sectionheadertapped:")         headerview .addgesturerecognizer(headertapped)         return headerview     } 

in sectionheadertapped

func sectionheadertapped(recognizer: uitapgesturerecognizer) {         let storyboard : uistoryboard = uistoryboard(name: "main", bundle: nil)         let vc : detailvc = storyboard.instantiateviewcontrollerwithidentifier("web-link") as! atldetailvc         vc.webviewloader() } 

in viewdidload

let url = "http://makeapppie.com/2014/10/28/swift-swift-using-uiwebviews-in-swift/" let requesturl = nsurl(string:url) let request = nsurlrequest(url: requesturl!) webview.loadrequest(request) //it working. but, in method call, why getting fatal error?? 

i've created similar app there no problem code. code:

class masterviewcontroller: uitableviewcontroller{     override func tableview(tableview: uitableview, numberofrowsinsection section: int) -> int {         return 5     }      override func tableview(tableview: uitableview, cellforrowatindexpath indexpath: nsindexpath) -> uitableviewcell {         let cell = tableview.dequeuereusablecellwithidentifier("cell") as! uitableviewcell          cell.textlabel?.text = "\(indexpath.row)"          return cell     }      override func tableview(tableview: uitableview, didselectrowatindexpath indexpath: nsindexpath) {         let dvc = self.splitviewcontroller?.viewcontrollers.last as! detailviewcontroller          dvc.webviewloader()     } }  class detailviewcontroller: uiviewcontroller {     @iboutlet weak var webview: uiwebview!      func webviewloader() {         println("came inside web view")         let url = "http://www.google.com"         let requesturl = nsurl(string:url)         let request = nsurlrequest(url: requesturl!)         webview.loadrequest(request) //fatal error while unwrapping     } } 

update 1

i've uploaded project