UIView disappears after user interaction - ios

Question

whenever I click a textfield inside the view, then click the other text field, the view disappears. Strange... Can anyone help?
I animate the view using facebook pop. Here is my animation engine code:
import UIKit
import pop
class AnimationEngine {
class var offScreenRightPosition: CGPoint {
return CGPoint(x: UIScreen.main.bounds.width + 250,y: UIScreen.main.bounds.midY - 75)
}
class var offScreenLeftPosition: CGPoint{
return CGPoint(x: -UIScreen.main.bounds.width,y: UIScreen.main.bounds.midY - 75)
}
class var offScreenTopPosition: CGPoint{
return CGPoint(x: UIScreen.main.bounds.midX,y: -UIScreen.main.bounds.midY)
}
class var screenCenterPosition: CGPoint {
return CGPoint(x: UIScreen.main.bounds.midX, y: UIScreen.main.bounds.midY - 75)
}
let ANIM_DELAY : Int = 1
var originalConstants = [CGFloat]()
var constraints: [NSLayoutConstraint]!
init(constraints: [NSLayoutConstraint]) {
for con in constraints {
originalConstants.append(con.constant)
con.constant = AnimationEngine.offScreenRightPosition.x
}
self.constraints = constraints
}
func animateOnScreen(_ delay: Int) {
let time = DispatchTime.now() + Double(Int64(Double(delay) * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC)
DispatchQueue.main.asyncAfter(deadline: time) {
var index = 0
repeat {
let moveAnim = POPSpringAnimation(propertyNamed: kPOPLayoutConstraintConstant)
moveAnim?.toValue = self.originalConstants[index]
moveAnim?.springBounciness = 8
moveAnim?.springSpeed = 8
if (index < 0) {
moveAnim?.dynamicsFriction += 10 + CGFloat(index)
}
let con = self.constraints[index]
con.pop_add(moveAnim, forKey: "moveOnScreen")
index += 1
} while (index < self.constraints.count)
}
}
class func animateToPosisition(_ view: UIView, position: CGPoint, completion: ((POPAnimation?, Bool) -> Void)!) {
let moveAnim = POPSpringAnimation(propertyNamed: kPOPLayerPosition)
moveAnim?.toValue = NSValue(cgPoint: position)
moveAnim?.springBounciness = 8
moveAnim?.springSpeed = 8
moveAnim?.completionBlock = completion
view.pop_add(moveAnim, forKey: "moveToPosition")
}
}
Then here is my viewcontroller code where the view is inside in:
import UIKit
import pop
class LoginVC: UIViewController, UITextFieldDelegate {
override var prefersStatusBarHidden: Bool {
return true
}
#IBOutlet weak var emailLoginVCViewConstraint: NSLayoutConstraint!
#IBOutlet weak var emailLoginVCView: MaterialView!
#IBOutlet weak var emailAddressTextField: TextFieldExtension!
#IBOutlet weak var passwordTextField: TextFieldExtension!
var animEngine : AnimationEngine!
override func viewDidAppear(_ animated: Bool) {
self.emailLoginVCView.isUserInteractionEnabled = true
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
self.view.bringSubview(toFront: emailAddressTextField)
self.animEngine = AnimationEngine(constraints: [emailLoginVCViewConstraint])
self.emailAddressTextField.delegate = self
self.passwordTextField.delegate = self
emailAddressTextField.allowsEditingTextAttributes = false
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
if (textField === emailAddressTextField) {
passwordTextField.becomeFirstResponder()
} else if (textField === passwordTextField) {
passwordTextField.resignFirstResponder()
} else {
// etc
}
return true
}
#IBAction func emailTapped(_ sender: AnyObject) {
AnimationEngine.animateToPosisition(emailLoginVCView, position: AnimationEngine.screenCenterPosition, completion: { (POPAnimation, Bool)
in
})
}
#IBAction func exitTapped(_ sender: AnyObject) {
AnimationEngine.animateToPosisition(emailLoginVCView, position: AnimationEngine.offScreenRightPosition, completion: { (POPAnimation, Bool)
in
})
}
}
Last here is my hierchy and options: (my view's name is emailLoginVCView). Also when I was debugging when I clicked another textfield I set a breakpoint so I got this info: enter image description here

Answer 1

I have a constraint that binds the center of the login view with the center of the main screen
when I create the AnimationEngine,I pass it that constraint, and it sets its constant to be the offScreenRightPosition.x
when I bring up the email login sheet, I'm not changing the constant of the constraint; I'm just changing the position of the view
which means that autolayout thinks it’s supposed to still be offscreen
when the second textfield becomes active, that’s somehow triggering auto-layout to re-evaluate the constraints, and it sees that the login view’s position doesn’t match what the constraint says it should be so....
Autolayout moves it offscreen
So if I add this in emailTapped(_:), the problem goes away :)
#IBAction func emailTapped(_ sender: AnyObject) {
AnimationEngine.animateToPosisition(emailLoginVCView, position: AnimationEngine.screenCenterPosition, completion: { (POPAnimation, Bool)
in
self.emailLoginVCViewConstraint.constant = 0
})
}