ios - NSCoreData - Textfield into float value -

i trying add textfield coredata float value, when user press submit button. have error

thread 1:exc_bad_access(code=1,address=0x1)

my attributes inside .xcdatamodel file , nsmanagedobject class set type float.

 @iboutlet weak var forceentered: uitextfield!  @iboutlet weak var stiffnessentered: uitextfield!    @ibaction func submit(sender: anyobject) {          let appdel : appdelegate = uiapplication.sharedapplication().delegate as! appdelegate         let contxt : nsmanagedobjectcontext = appdel.managedobjectcontext!         let en = nsentitydescription.entityforname("springvariables", inmanagedobjectcontext: contxt)         var newitem = springmodel(entity:en!,insertintomanagedobjectcontext: contxt)          newitem.stiffness = (stiffnessentered.text nsstring).floatvalue //error message shows here.         newitem.force = (forceentered.text nsstring).floatvalue    }