Jak mogę animować ruch widoku lub obrazu wzdłuż zakrzywionej ścieżki?

Tworzę aplikację handlową. Kiedy dodaję przedmiot do koszyka, chcę stworzyć efekt, w którym obraz przedmiotu podąża po zakrzywionej ścieżce i kończy się na karcie koszyka.

Jak mogę stworzyć animację obrazu wzdłuż takiej krzywej?

Aby rozszerzyć to, co powiedział Nikolai, najlepszym sposobem na rozwiązanie tego problemu jest użycie animacji podstawowej do animacji ruchu obrazu lub widoku wzdłuż ścieżki Beziera. Osiąga się to za pomocą CAKeyframeAnimation. Na przykład użyłem następującego kodu do animacji obrazu widoku na ikonę wskazującą zapis (jak widać na wideo dla tej aplikacji ):

Przede wszystkim zaimportuj plik nagłówkowy QuartzCore #import <QuartzCore/QuartzCore.h>

UIImageView *imageViewForAnimation = [[UIImageView alloc] initWithImage:imageToAnimate];
imageViewForAnimation.alpha = 1.0f;
CGRect imageFrame = imageViewForAnimation.frame;
//Your image frame.origin from where the animation need to get start
CGPoint viewOrigin = imageViewForAnimation.frame.origin;
viewOrigin.y = viewOrigin.y + imageFrame.size.height / 2.0f;
viewOrigin.x = viewOrigin.x + imageFrame.size.width / 2.0f;

imageViewForAnimation.frame = imageFrame;
imageViewForAnimation.layer.position = viewOrigin;
[self.view addSubview:imageViewForAnimation];

// Set up fade out effect
CABasicAnimation *fadeOutAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
[fadeOutAnimation setToValue:[NSNumber numberWithFloat:0.3]];
fadeOutAnimation.fillMode = kCAFillModeForwards;
fadeOutAnimation.removedOnCompletion = NO;

// Set up scaling
CABasicAnimation *resizeAnimation = [CABasicAnimation animationWithKeyPath:@"bounds.size"];
[resizeAnimation setToValue:[NSValue valueWithCGSize:CGSizeMake(40.0f, imageFrame.size.height * (40.0f / imageFrame.size.width))]];
resizeAnimation.fillMode = kCAFillModeForwards;
resizeAnimation.removedOnCompletion = NO;

// Set up path movement
CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
pathAnimation.calculationMode = kCAAnimationPaced;
pathAnimation.fillMode = kCAFillModeForwards;
pathAnimation.removedOnCompletion = NO;
//Setting Endpoint of the animation
CGPoint endPoint = CGPointMake(480.0f - 30.0f, 40.0f);
//to end animation in last tab use 
//CGPoint endPoint = CGPointMake( 320-40.0f, 480.0f);
CGMutablePathRef curvedPath = CGPathCreateMutable();
CGPathMoveToPoint(curvedPath, NULL, viewOrigin.x, viewOrigin.y);
CGPathAddCurveToPoint(curvedPath, NULL, endPoint.x, viewOrigin.y, endPoint.x, viewOrigin.y, endPoint.x, endPoint.y);
pathAnimation.path = curvedPath;
CGPathRelease(curvedPath);

CAAnimationGroup *group = [CAAnimationGroup animation]; 
group.fillMode = kCAFillModeForwards;
group.removedOnCompletion = NO;
[group setAnimations:[NSArray arrayWithObjects:fadeOutAnimation, pathAnimation, resizeAnimation, nil]];
group.duration = 0.7f;
group.delegate = self;
[group setValue:imageViewForAnimation forKey:@"imageViewBeingAnimated"];

[imageViewForAnimation.layer addAnimation:group forKey:@"savingAnimation"];

[imageViewForAnimation release];

Sposób animacji wzdłuż CGPath przy użyciu UIView.animateKeyframes(Swift 4)

private func animateNew() {

   let alphaFrom: CGFloat = 1
   let alphaTo: CGFloat = 0.3
   let sizeFrom = CGSize(width: 40, height: 20)
   let sizeTo = CGSize(width: 80, height: 60)
   let originFrom = CGPoint(x: 40, y: 40)
   let originTo = CGPoint(x: 240, y: 480)

   let deltaWidth = sizeTo.width - sizeFrom.width
   let deltaHeight = sizeTo.height - sizeFrom.height
   let deltaAlpha = alphaTo - alphaFrom

   // Setting default values
   imageViewNew.alpha = alphaFrom
   imageViewNew.frame = CGRect(origin: originFrom, size: sizeFrom)

   // CGPath setup for calculating points on curve.
   let curvedPath = CGMutablePath()
   curvedPath.move(to: originFrom)
   curvedPath.addQuadCurve(to: originTo, control: CGPoint(x: originFrom.x,  y: originTo.y))
   let path = Math.BezierPath(cgPath: curvedPath, approximationIterations: 10)

   // Calculating timing parameters
   let duration: TimeInterval = 0.7
   let numberOfKeyFrames = 16
   let curvePoints = Math.Easing.timing(numberOfSteps: numberOfKeyFrames, .easeOutQuad)

   UIView.animateKeyframes(withDuration: duration, delay: 0, options: [.calculationModeCubic], animations: {
      // Iterating curve points and adding key frames
      for point in curvePoints {
         let origin = path.point(atPercentOfLength: point.end)
         let size = CGSize(width: sizeFrom.width + deltaWidth * point.end,
                           height: sizeFrom.height + deltaHeight * point.end)
         let alpha = alphaFrom + deltaAlpha * point.end
         UIView.addKeyframe(withRelativeStartTime: TimeInterval(point.start), relativeDuration: TimeInterval(point.duration)) {
            self.imageViewNew.frame = CGRect(origin: origin, size: size)
            self.imageViewNew.alpha = alpha
         }
      }
   }, completion: nil)
}

Plik: Math.Easing.swift

// Inspired by: RBBAnimation/RBBEasingFunction.m: https://github.com/robb/RBBAnimation/blob/master/RBBAnimation/RBBEasingFunction.m
extension Math { public struct Easing { } }

extension Math.Easing {

   public enum Algorithm: Int {
      case linear, easeInQuad, easeOutQuad, easeInOutQuad
   }

   @inline(__always)
   public static func linear(_ t: CGFloat) -> CGFloat {
      return t
   }

   @inline(__always)
   public static func easeInQuad(_ t: CGFloat) -> CGFloat  {
      return t * t
   }

   @inline(__always)
   public static func easeOutQuad(_ t: CGFloat) -> CGFloat  {
      return t * (2 - t)
   }

   @inline(__always)
   public static func easeInOutQuad(_ t: CGFloat) -> CGFloat  {
      if t < 0.5 {
         return 2 * t * t
      } else {
         return -1 + (4 - 2 * t) * t
      }
   }
}

extension Math.Easing {

   public struct Timing {

      public let start: CGFloat
      public let end: CGFloat
      public let duration: CGFloat

      init(start: CGFloat, end: CGFloat) {
         self.start = start
         self.end = end
         self.duration = end - start
      }

      public func multiplying(by: CGFloat) -> Timing {
         return Timing(start: start * by, end: end * by)
      }
   }

   public static func process(_ t: CGFloat, _ algorithm: Algorithm) -> CGFloat {
      switch algorithm {
      case .linear:
         return linear(t)
      case .easeInQuad:
         return easeInQuad(t)
      case .easeOutQuad:
         return easeOutQuad(t)
      case .easeInOutQuad:
         return easeInOutQuad(t)
      }
   }

   public static func timing(numberOfSteps: Int, _ algorithm: Algorithm) -> [Timing] {
      var result: [Timing] = []
      let linearStepSize = 1 / CGFloat(numberOfSteps)
      for step in (0 ..< numberOfSteps).reversed() {
         let linearValue = CGFloat(step) * linearStepSize
         let processedValue = process(linearValue, algorithm) // Always in range 0 ... 1
         let lastValue = result.last?.start ?? 1
         result.append(Timing(start: processedValue, end: lastValue))
      }
      result = result.reversed()
      return result
   }
}

Plik: Math.BezierPath.swift. Spójrz na tę odpowiedź SO: https://stackoverflow.com/a/50782971/1418981

Można animować właściwość centrum UIView za pomocą CAKeyframeAnimation. Zobacz przewodnik programowania CoreAnimation .

Wersja Swift 4 podobna do przykładu ObjC z oryginalnej odpowiedzi.

class KeyFrameAnimationsViewController: ViewController {

   let sampleImage = ImageFactory.image(size: CGSize(width: 160, height: 120), fillColor: .blue)

   private lazy var imageView = ImageView(image: sampleImage)
   private lazy var actionButton = Button(title: "Animate").autolayoutView()

   override func setupUI() {
      view.addSubviews(imageView, actionButton)
      view.backgroundColor = .gray
   }

   override func setupLayout() {
      LayoutConstraint.withFormat("|-[*]", actionButton).activate()
      LayoutConstraint.withFormat("V:|-[*]", actionButton).activate()
   }

   override func setupHandlers() {
      actionButton.setTouchUpInsideHandler { [weak self] in
         self?.animate()
      }
   }

   private func animate() {

      imageView.alpha = 1
      let isRemovedOnCompletion = false

      let sizeFrom = CGSize(width: 40, height: 20)
      let sizeTo = CGSize(width: 80, height: 60)
      let originFrom = CGPoint(x: 40, y: 40)
      let originTo = CGPoint(x: 240, y: 480)

      imageView.frame = CGRect(origin: originFrom, size: sizeFrom)
      imageView.layer.position = originFrom

      // Set up fade out effect
      let fadeOutAnimation = CABasicAnimation(keyPath: "opacity")
      fadeOutAnimation.toValue = 0.3
      fadeOutAnimation.fillMode = kCAFillModeForwards
      fadeOutAnimation.isRemovedOnCompletion = isRemovedOnCompletion

      // Set up scaling
      let resizeAnimation = CABasicAnimation(keyPath: "bounds.size")
      resizeAnimation.toValue = sizeTo
      resizeAnimation.fillMode = kCAFillModeForwards
      resizeAnimation.isRemovedOnCompletion = isRemovedOnCompletion

      // Set up path movement
      let pathAnimation = CAKeyframeAnimation(keyPath: "position")
      pathAnimation.calculationMode = kCAAnimationPaced;
      pathAnimation.fillMode = kCAFillModeForwards;
      pathAnimation.isRemovedOnCompletion = isRemovedOnCompletion

      // Setting Endpoint of the animation to end animation in last tab use
      let curvedPath = CGMutablePath()
      curvedPath.move(to: originFrom)
      // About curves: https://www.bignerdranch.com/blog/core-graphics-part-4-a-path-a-path/
      curvedPath.addQuadCurve(to: originTo, control: CGPoint(x: originFrom.x,  y: originTo.y))
      pathAnimation.path = curvedPath

      let group = CAAnimationGroup()
      group.fillMode = kCAFillModeForwards
      group.isRemovedOnCompletion = isRemovedOnCompletion
      group.animations = [fadeOutAnimation, pathAnimation, resizeAnimation]
      group.duration = 0.7
      group.setValue(imageView, forKey: "imageViewBeingAnimated")

      imageView.layer.add(group, forKey: "savingAnimation")
   }
}