How can i put the UIElement behind the screen and get it with animation on view?-CodePudding

I want my textFields to hid behind the screen when "viewDidLoad" calls and then appearing smoothly on view by pushing a button. I just have a function like:

UIView.animate(duration: 0.5, options: .curveEaseIn) {
    textField.center.x -= view.frame.width
}

And it was working until added constraints. And now the textField just hiding behind the screen and returning back immediately. I think solution in using "Dispatch.main" but i didn't have success.

Each field has a CenterX constraint... but we will set the Priority to High (750):

Then, we'll add "hidden" constraints as properties in the view controller:

var nameHiddenConstraint: NSLayoutConstraint!
var surnameHiddenConstraint: NSLayoutConstraint!

and in viewDidLoad we'll create Priority : Required constraints to start those fields "off-screen." To animate the fields into-view, we can deactivate the "hidden" constraints and let auto-layout use the Storyboard-created CenterX constraints.

Here's some example code:

class ConAnimVC: UIViewController {
    
    @IBOutlet var nameField: UITextField!
    @IBOutlet var surnameField: UITextField!

    var nameHiddenConstraint: NSLayoutConstraint!
    var surnameHiddenConstraint: NSLayoutConstraint!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // constraints created via code have a default Priority of Required
        //  so they will "override" the centerX constraints created in Storyboard
        
        // constrain Trailing of nameField 20-points to the left of view.leading
        nameHiddenConstraint = nameField.trailingAnchor.constraint(equalTo: view.leadingAnchor, constant: -20.0)
        // constrain Leading of surnameField 20-points to the right of view.trailing
        surnameHiddenConstraint = surnameField.leadingAnchor.constraint(equalTo: view.trailingAnchor, constant: 20.0)

        // activate those two constraints
        nameHiddenConstraint.isActive = true
        surnameHiddenConstraint.isActive = true
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        // deactivate the code-created constraints
        nameHiddenConstraint.isActive = false
        surnameHiddenConstraint.isActive = false
        // animate the constraint changes
        UIView.animate(withDuration: 0.5, delay: 0.0, options: .curveEaseIn, animations: {
            self.view.layoutIfNeeded()
        }, completion: nil)
    }
    
}

and here's the source code for that Storyboard:

<?xml version="1.0" encoding="UTF-8"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="20037" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="Y6W-OH-hqX">
    <device id="retina4_7" orientation="portrait" appearance="light"/>
    <dependencies>
        <deployment identifier="iOS"/>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="20020"/>
        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
        <capability name="System colors in document resources" minToolsVersion="11.0"/>
        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
    </dependencies>
    <scenes>
        <!--Con AnimVC-->
        <scene sceneID="s0d-6b-0kx">
            <objects>
                <viewController id="Y6W-OH-hqX" customClass="ConAnimVC" customModule="QuickTest" customModuleProvider="target" sceneMemberID="viewController">
                    <view key="view" contentMode="scaleToFill" id="5EZ-qb-Rvc">
                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                        <subviews>
                            <textField opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="left" contentVerticalAlignment="center" text="name" borderStyle="roundedRect" textAlignment="natural" minimumFontSize="17" translatesAutoresizingMaskIntoConstraints="NO" id="19l-e9-8x6">
                                <rect key="frame" x="37.5" y="40" width="300" height="34"/>
                                <color key="backgroundColor" white="0.66666666666666663" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                <color key="textColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                <fontDescription key="fontDescription" type="system" pointSize="14"/>
                                <textInputTraits key="textInputTraits"/>
                            </textField>
                            <textField opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="left" contentVerticalAlignment="center" text="surname" borderStyle="roundedRect" textAlignment="natural" minimumFontSize="17" translatesAutoresizingMaskIntoConstraints="NO" id="LRb-yP-Zgy">
                                <rect key="frame" x="37.5" y="82" width="300" height="34"/>
                                <color key="backgroundColor" white="0.66666666669999997" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                <color key="textColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                <fontDescription key="fontDescription" type="system" pointSize="14"/>
                                <textInputTraits key="textInputTraits"/>
                            </textField>
                        </subviews>
                        <viewLayoutGuide key="safeArea" id="vDu-zF-Fre"/>
                        <color key="backgroundColor" systemColor="systemGray5Color"/>
                        <constraints>
                            <constraint firstItem="19l-e9-8x6" firstAttribute="width" secondItem="5EZ-qb-Rvc" secondAttribute="width" multiplier="0.8" id="UPO-jI-q7U"/>
                            <constraint firstItem="LRb-yP-Zgy" firstAttribute="centerX" secondItem="5EZ-qb-Rvc" secondAttribute="centerX" priority="750" id="VV4-3M-Y1v"/>
                            <constraint firstItem="LRb-yP-Zgy" firstAttribute="top" secondItem="19l-e9-8x6" secondAttribute="bottom" constant="8" id="c4i-Eb-DGs"/>
                            <constraint firstItem="19l-e9-8x6" firstAttribute="centerX" secondItem="5EZ-qb-Rvc" secondAttribute="centerX" priority="750" id="iDc-Rz-7R9"/>
                            <constraint firstItem="LRb-yP-Zgy" firstAttribute="width" secondItem="5EZ-qb-Rvc" secondAttribute="width" multiplier="0.8" id="m27-e9-kZQ"/>
                            <constraint firstItem="19l-e9-8x6" firstAttribute="top" secondItem="vDu-zF-Fre" secondAttribute="top" constant="40" id="s3k-lV-qLH"/>
                        </constraints>
                    </view>
                    <connections>
                        <outlet property="nameField" destination="19l-e9-8x6" id="ZGF-91-Shz"/>
                        <outlet property="surnameField" destination="LRb-yP-Zgy" id="xWU-uW-fTZ"/>
                    </connections>
                </viewController>
                <placeholder placeholderIdentifier="IBFirstResponder" id="Ief-a0-LHa" userLabel="First Responder" customClass="UIResponder" sceneMemberID="firstResponder"/>
            </objects>
            <point key="canvasLocation" x="71" y="96"/>
        </scene>
    </scenes>
    <resources>
        <systemColor name="systemGray5Color">
            <color red="0.89803921568627454" green="0.89803921568627454" blue="0.91764705882352937" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
        </systemColor>
    </resources>
</document>