ios - Move view with keyboard using swift 3 -

i have app has text field on lower half of view , have navigation controller bottom of page.

how go moving view upwards while typing can see i'm typing , moving down original place when keyboard disappears? don't want move navigation controller

you have observe changes in keyboard frame , act accordingly show uiview (uitextfield, uitextview etc.) above keyboard.

notificationcenter apple documentation: https://developer.apple.com/documentation/foundation/notificationcenter

other answers @ stackoverflow: how make uitextfield move when keyboard present?

here quick example of view controller:

import uikit  class exampleviewcontroller: uiviewcontroller {    // mark: - properties    @iboutlet weak var exampletextview1: uitextview!   @iboutlet weak var exampletextview2: uitextview!    @iboutlet weak var exampletextview1bottomconstraint: nslayoutconstraint!   @iboutlet weak var exampletextview2bottomconstraint: nslayoutconstraint!    var exampletextview1bottomconstraintinitialconstant: cgfloat!   var exampletextview2bottomconstraintinitialconstant: cgfloat!    var keyboardvisibilityobservers: [nsobjectprotocol] = []    // mark: - view lifecycle    override func viewdidload() {     super.viewdidload()      exampletextview1bottomconstraintinitialconstant = exampletextview1bottomconstraint.constant     exampletextview2bottomconstraintinitialconstant = exampletextview2bottomconstraint.constant   }    override func viewwillappear(_ animated: bool) {     super.viewwillappear(animated)      // add observers text view 1     keyboardvisibilityobservers.append(createshowkeyboardobserver(keyboardtrigger: exampletextview1, distance: 10.0, constraint: exampletextview1bottomconstraint))     keyboardvisibilityobservers.append(createhidekeyboardobserver(keyboardtrigger: exampletextview1, constraint: exampletextview1bottomconstraint, initialconstraintconstant: exampletextview1bottomconstraintinitialconstant))       // add observers text view 2     keyboardvisibilityobservers.append(createshowkeyboardobserver(keyboardtrigger: exampletextview2, distance: 10.0, constraint: exampletextview2bottomconstraint))     keyboardvisibilityobservers.append(createhidekeyboardobserver(keyboardtrigger: exampletextview2, constraint: exampletextview2bottomconstraint, initialconstraintconstant: exampletextview2bottomconstraintinitialconstant))    }    override func viewwilldisappear(_ animated: bool) {     super.viewwilldisappear(animated)      removeallkeyboardvisibilitynotificationobservers()   }    // mark: - keyboard event handling    private func createshowkeyboardobserver(keyboardtrigger: uiview, distance: cgfloat, constraint: nslayoutconstraint) -> nsobjectprotocol {     return notificationcenter.default.addobserver(forname: .uikeyboardwillshow, object: nil, queue: nil) { (notification) in        if let userinfo = notification.userinfo,         let endframe = (userinfo[uikeyboardframeenduserinfokey] as? nsvalue)?.cgrectvalue {          // animation duration , curve user info dictionary         let duration: timeinterval = (userinfo[uikeyboardanimationdurationuserinfokey] as? nsnumber)?.doublevalue ?? 0         let animationcurverawnsn = userinfo[uikeyboardanimationcurveuserinfokey] as? nsnumber         let animationcurveraw = animationcurverawnsn?.uintvalue ?? uiviewanimationoptions.curveeaseinout.rawvalue         let animationcurve: uiviewanimationoptions = uiviewanimationoptions(rawvalue: animationcurveraw)          let originyaxisofkeyboardtrigger = keyboardtrigger.convert(keyboardtrigger.bounds.origin, to: self.view).y         let preferredoriginyaxisofkeyboardtrigger = endframe.origin.y - distance - keyboardtrigger.bounds.height          constraint.constant = constraint.constant - (originyaxisofkeyboardtrigger - preferredoriginyaxisofkeyboardtrigger)          // animate changes         uiview.animate(withduration: duration,                        delay: timeinterval(0),                        options: animationcurve,                        animations: { self.view.layoutifneeded() },                        completion: nil)       }     }   }    private func createhidekeyboardobserver(keyboardtrigger: uiview, constraint: nslayoutconstraint, initialconstraintconstant: cgfloat) -> nsobjectprotocol {     return notificationcenter.default.addobserver(forname: .uikeyboardwillhide, object: nil, queue: nil) { (notification) in        if let userinfo = notification.userinfo {          // animation duration , curve user info dictionary         let duration: timeinterval = (userinfo[uikeyboardanimationdurationuserinfokey] as? nsnumber)?.doublevalue ?? 0         let animationcurverawnsn = userinfo[uikeyboardanimationcurveuserinfokey] as? nsnumber         let animationcurveraw = animationcurverawnsn?.uintvalue ?? uiviewanimationoptions.curveeaseinout.rawvalue         let animationcurve: uiviewanimationoptions = uiviewanimationoptions(rawvalue: animationcurveraw)          constraint.constant = initialconstraintconstant          // animate changes         uiview.animate(withduration: duration,                        delay: timeinterval(0),                        options: animationcurve,                        animations: { self.view.layoutifneeded() },                        completion: nil)       }     }   }    private func removeallkeyboardvisibilitynotificationobservers() {     keyboardvisibilityobservers.foreach { (observer) in       notificationcenter.default.removeobserver(observer)     }      keyboardvisibilityobservers.removeall()   }  }