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Víctor Gonzal
Asked: 2020-12-28 12:33:18 +0800 CST 2020-12-28 12:33:18 +0800 CST

Prevent items in a view from being hidden when calling viewDidLayoutSubviews

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I have been following a tutorial on how to implement a login with parse with the function of logging in with Facebook and Twitter, however, I find a detail.

In principle, the elements of the main view are hidden by means of the function viewDidLayoutSubviews, that is, they are sent to the bottom of the screen and then move up in the form of animation, this animation is executed in the function viewDidAppear.

So far everything is perfect, however when I select one of those textFieldsthat are part of the view to enter a text, obviously the keyboard appears and in theory I should move the elements up so as not to hide them when writing, here I suppose that it is activates the function again viewDidLayoutSubviewsand executes the code snippet that hides me all the elements at the bottom as it is done when the application loads to make the animation possible.

How can I prevent the elements from disappearing every time I try to write to any of the textFields?

override func viewDidLoad() {
        super.viewDidLoad()

 // create an array of all the views we want to animate in when we launch the screen

        viewsToAnimate = [self.logInView?.usernameField, self.logInView?.passwordField, self.logInView?.logInButton, self.logInView?.passwordForgottenButton, self.logInView?.facebookButton, self.logInView?.signUpButton, self.logInView?.logo]
}

override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()


        // We to position all the views off the bottom of the screen
        // and then make them rise back to where they should be
        // so we track their final position in an array
        // but change their frame so they are shifted downwards off the screen


        viewsFinalYPosition = [CGFloat]();
        for viewToAnimate in viewsToAnimate {
            //print(viewToAnimate.frame)
            let currentFrame = viewToAnimate.frame
            print(viewsFinalYPosition.count)
            viewsFinalYPosition.append(currentFrame.origin.y)
            viewToAnimate.frame = CGRectMake(currentFrame.origin.x, self.view.frame.height + currentFrame.origin.y, currentFrame.width, currentFrame.height)
        }
    }

override func viewDidAppear(animated: Bool) {


        super.viewDidAppear(animated)


        // Now we'll animate all our views back into view
        // and, using the final position we stored, we'll
        // reset them to where they should be
        if viewsFinalYPosition.count == self.viewsToAnimate.count {
            UIView.animateWithDuration(1, delay: 0.0, options: .CurveEaseInOut,  animations: { () -> Void in
                for viewToAnimate in self.viewsToAnimate {
                    print(viewToAnimate.frame)
                    let currentFrame = viewToAnimate.frame
                     print(self.viewsFinalYPosition.count)
                    viewToAnimate.frame = CGRectMake(currentFrame.origin.x, self.viewsFinalYPosition.removeAtIndex(0), currentFrame.width, currentFrame.height)
                }
                }, completion: nil)
        }
    }

Views Dissapear

https://dl.dropboxusercontent.com/u/4915071/viewsDissapear.mov

swift

1 Answers

  1. Best Answer

    Give them the starting position (hidden) in the viewDidLoador add a boolean property:

    var initialPositionSet = false

    So that you viewDidLayoutSubviewsput it in truewhen the elements have already been hidden:

    override func viewDidLayoutSubviews() {
    if !self.initialPositionSet {
        self.initialPositionSet = true

        // establecer posición inicial
    }
}

    I think something like this might work for you.

    • 2