trying to animate a constraint in swift

Question

I have a UITextField that I want to enlarge its width when tapped on  I set up the constraints and made sure the constraint on the left has the lower priority then the one that I am trying to animate on the right side  Here is the code that I am trying to use     move the input box UIView animateWithDuration 10 5  animations        self nameInputConstraint constant   8        completion             value  Bool  in         println  quot  gt  gt  gt  move const quot       This works  but it seems to just happen instantly and there doesn t seem to be any movement  I tried to set it 10 seconds to make sure I wasn t missing anything  but I got the same results  nameInputConstraint is the name of the constraint that I control dragged to connect into my class from IB

User · Answer

In my case  I only updated the custom view      DO NOT LIKE THIS customView layoutIfNeeded         Change to view layoutIfNeeded   UIView animate withDuration  0 5       customViewConstraint constant   100 0    customView layoutIfNeeded      Change to view layoutIfNeeded

User · Answer

SWIFT 4 x    self mConstraint constant   100 0 UIView animate withDuration  0 3            self view layoutIfNeeded       Example with completion    self mConstraint constant   100 UIView animate withDuration  0 3  animations            self view layoutIfNeeded          completion   res in           Do something

User · Answer

Watch this   The video says that you need to just add self view layoutIfNeeded   like the following   UIView animate withDuration  1 0  animations           self centerX constant -  75        self view layoutIfNeeded      completion  nil

User · Answer

With Swift 5 and iOS 12 3  according to your needs  you may choose one of the 3 following ways in order to solve your problem      1  Using UIView s animate withDuration animations   class method  animate withDuration animations   has the following declaration      Animate changes to one or more views using the specified duration    class func animate withDuration duration  TimeInterval  animations   escaping    - gt  Void    The Playground code below shows a possible implementation of animate withDuration animations   in order to animate an Auto Layout constraint s constant change   import UIKit import PlaygroundSupport  class ViewController  UIViewController        let textView   UITextView       lazy var heightConstraint   textView heightAnchor constraint equalToConstant  50       override func viewDidLoad             view backgroundColor    white         view addSubview textView           textView backgroundColor    orange         textView isEditable   false         textView text    Lorem ipsum dolor sit amet  consectetur adipiscing elit  sed do eiusmod tempor incididunt ut labore et dolore magna aliqua  Ut enim ad minim veniam  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat  Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur  Excepteur sint occaecat cupidatat non proident  sunt in culpa qui officia deserunt mollit anim id est laborum            textView translatesAutoresizingMaskIntoConstraints   false         textView topAnchor constraint equalToSystemSpacingBelow  view layoutMarginsGuide topAnchor  multiplier  1  isActive   true         textView leadingAnchor constraint equalTo  view layoutMarginsGuide leadingAnchor  isActive   true         textView trailingAnchor constraint equalTo  view layoutMarginsGuide trailingAnchor  isActive   true         heightConstraint isActive   true          let tapGesture   UITapGestureRecognizer target  self  action   selector doIt               textView addGestureRecognizer tapGesture              objc func doIt   sender  UITapGestureRecognizer            heightConstraint constant   heightConstraint constant    50   150   50         UIView animate withDuration  2                self view layoutIfNeeded                       PlaygroundPage current liveView   ViewController        2  Using UIViewPropertyAnimator s init duration curve animations   initialiser and startAnimation   method  init duration curve animations   has the following declaration      Initializes the animator with a built-in UIKit timing curve    convenience init duration  TimeInterval  curve  UIViewAnimationCurve  animations      - gt  Void     nil    The Playground code below shows a possible implementation of init duration curve animations   and startAnimation   in order to animate an Auto Layout constraint s constant change   import UIKit import PlaygroundSupport  class ViewController  UIViewController        let textView   UITextView       lazy var heightConstraint   textView heightAnchor constraint equalToConstant  50       override func viewDidLoad             view backgroundColor    white         view addSubview textView           textView backgroundColor    orange         textView isEditable   false         textView text    Lorem ipsum dolor sit amet  consectetur adipiscing elit  sed do eiusmod tempor incididunt ut labore et dolore magna aliqua  Ut enim ad minim veniam  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat  Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur  Excepteur sint occaecat cupidatat non proident  sunt in culpa qui officia deserunt mollit anim id est laborum            textView translatesAutoresizingMaskIntoConstraints   false         textView topAnchor constraint equalToSystemSpacingBelow  view layoutMarginsGuide topAnchor  multiplier  1  isActive   true         textView leadingAnchor constraint equalTo  view layoutMarginsGuide leadingAnchor  isActive   true         textView trailingAnchor constraint equalTo  view layoutMarginsGuide trailingAnchor  isActive   true         heightConstraint isActive   true          let tapGesture   UITapGestureRecognizer target  self  action   selector doIt               textView addGestureRecognizer tapGesture              objc func doIt   sender  UITapGestureRecognizer            heightConstraint constant   heightConstraint constant    50   150   50         let animator   UIViewPropertyAnimator duration  2  curve   linear  animations                self view layoutIfNeeded                      animator startAnimation             PlaygroundPage current liveView   ViewController        3  Using UIViewPropertyAnimator s runningPropertyAnimator withDuration delay options animations completion   class method  runningPropertyAnimator withDuration delay options animations completion   has the following declaration      Creates and returns an animator object that begins running its animations immediately    class func runningPropertyAnimator withDuration duration  TimeInterval  delay  TimeInterval  options  UIViewAnimationOptions       animations   escaping    - gt  Void  completion    UIViewAnimatingPosition  - gt  Void     nil  - gt  Self   The Playground code below shows a possible implementation of runningPropertyAnimator withDuration delay options animations completion   in order to animate an Auto Layout constraint s constant change   import UIKit import PlaygroundSupport  class ViewController  UIViewController        let textView   UITextView       lazy var heightConstraint   textView heightAnchor constraint equalToConstant  50       override func viewDidLoad             view backgroundColor    white         view addSubview textView           textView backgroundColor    orange         textView isEditable   false         textView text    Lorem ipsum dolor sit amet  consectetur adipiscing elit  sed do eiusmod tempor incididunt ut labore et dolore magna aliqua  Ut enim ad minim veniam  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat  Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur  Excepteur sint occaecat cupidatat non proident  sunt in culpa qui officia deserunt mollit anim id est laborum            textView translatesAutoresizingMaskIntoConstraints   false         textView topAnchor constraint equalToSystemSpacingBelow  view layoutMarginsGuide topAnchor  multiplier  1  isActive   true         textView leadingAnchor constraint equalTo  view layoutMarginsGuide leadingAnchor  isActive   true         textView trailingAnchor constraint equalTo  view layoutMarginsGuide trailingAnchor  isActive   true         heightConstraint isActive   true          let tapGesture   UITapGestureRecognizer target  self  action   selector doIt               textView addGestureRecognizer tapGesture              objc func doIt   sender  UITapGestureRecognizer            heightConstraint constant   heightConstraint constant    50   150   50         UIViewPropertyAnimator runningPropertyAnimator withDuration  2  delay  0  options      animations                self view layoutIfNeeded                        PlaygroundPage current liveView   ViewController

User · Answer

You need to first change the constraint and then animate the update  This should be in the superview  self nameInputConstraint constant   8  Swift 2 UIView animateWithDuration 0 5        self view layoutIfNeeded      Swift 3  4  5 UIView animate withDuration  0 5        self view layoutIfNeeded

User · Answer

It s very important to point out that view layoutIfNeeded   applies to the view subviews only   Therefore to animate the view constraint  it is important to call it on the view-to-animate superview as follows       topConstraint constant   heightShift      UIView animate withDuration  0 3                request layout on the  superview          self view superview  layoutIfNeeded           An example for a simple layout as follows   class MyClass            Container view     let container   UIView               View attached to container         let view   UIView            Top constraint to animate     var topConstraint   NSLayoutConstraint             Create the UI hierarchy and constraints     func createUI             container addSubview view              Create the top constraint         topConstraint   view topAnchor constraint equalTo  container topAnchor  constant  0            view translatesAutoresizingMaskIntoConstraints   false             Activate constaint s          NSLayoutConstraint activate              topConstraint                            Update view constraint with animation     func updateConstraint heightShift  CGFloat            topConstraint constant   heightShift          UIView animate withDuration  0 3                    request layout on the  superview              self view superview  layoutIfNeeded

[xcode] trying to animate a constraint in swift

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