UIView: How to animate CALayer frame with shadow?

Question

I added a shadow layer as a sublayer to UIView's layer. Following is an added method for UIView subclass:

- (void)addDefaultShadowSubview {
    self.shadowSubview = [[[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, self.frame.size.width, self.frame.size.height)] autorelease];

    CALayer *shadowLayer = [CALayer layer];
    shadowLayer.backgroundColor = self.backgroundColor.CGColor;
    shadowLayer.shadowOffset = CGSizeMake(0, 3);
    shadowLayer.shadowRadius = 5.0;
    shadowLayer.shadowColor = [UIColor blackColor].CGColor;
    shadowLayer.shadowOpacity = 0.8;

    shadowLayer.frame = self.shadowSubview.frame;

    [self.shadowSubview.layer addSublayer:shadowLayer];

    self.shadowSubview.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    [self addSubview:self.shadowSubview];
    [self sendSubviewToBack:self.shadowSubview];
}

I would like to keep it as a part of resizing animation of the an UIView with shadowSubview. But can't find the right way to do it while using + (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion;

[UIView animateWithDuration:durationDefaultAnimation
                     animations:^{
                         [self.viewWithShadowSubview setFrame:enlargedFrame];
                     }
                     completion:^(BOOL finished) {
                         [self modifyInsetForCurrentImageviewWithAnimation:YES];
                     }];

Please help me to know to right way. Tried to learn about CABasicAnimation, but can't find the way to apply it to this case.

Why aren't you setting the shadow on the shadowSubview layer? — David Rönnqvist, Mar 03 '12 at 16:54

score 1 · Answer 1 · answered Feb 13 '18 at 10:31

CALayer layer frame and shadow animation: You can apply shadow on CALayer itself and adjust the frame. Or have different layer for shadow and frame, then animate it according to your requirements..

i have written one sample code which worked for me..

    //change in CALayer frame
    let startFrame = CGRect.init(x: -5, y: -5, width: view.frame.size.width+10, height: view.frame.size.height+10)
    let endFrame = CGRect.init(x: -15, y: -15, width: view.frame.size.width+30, height: view.frame.size.height+30)

    //Frame
    let layer = CALayer.init()
    layer.frame = startFrame
    layer.borderWidth = 3.0
    layer.borderColor = UIColor.white.cgColor
    layer.backgroundColor = UIColor.clear.cgColor
    view.layer.addSublayer(layer)

    //Shadow
    view.layer.shadowRadius = 4.0
    view.layer.shadowColor = UIColor.black.cgColor
    view.layer.shadowOffset = CGSize.init(width: 3.0, height: 3.0)

    //Animaiton for shadow
    let animation = CABasicAnimation(keyPath: "shadowOpacity")
    animation.fromValue = 0.0
    animation.toValue = 0.9
    animation.duration = 5.0
    CATransaction.setCompletionBlock {

    }

    //Animation for Frame
    let baseAnimation = CABasicAnimation.init(keyPath: "bounds")
    baseAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
    baseAnimation.duration = 5.0
    baseAnimation.fromValue = NSValue.init(cgRect: startFrame)
    baseAnimation.toValue = NSValue.init(cgRect: endFrame)
    layer.frame = endFrame
    CATransaction.setCompletionBlock {

    }

    //Group animation - if u have multiple CA animation then group else no need to group it
    let animationGroup = CAAnimationGroup.init()
    animationGroup.duration = 5.0
    animationGroup.animations = [animation,baseAnimation]

    view.layer.add(animationGroup, forKey: nil)

score 1 · Answer 2 · edited May 23 '17 at 11:56

1

I suggest you also set the shadow layer's shadowPath property and then refer to Animating CALayer's shadowPath property for implementing the shadow path's animation.

edited May 23 '17 at 11:56

Community

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answered Mar 18 '12 at 21:59

MrMage

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score 0 · Answer 3 · answered Mar 18 '12 at 19:26

Set the shadow directly on your shadowSubview like David say.

You can do this by replacing:

    - (void)addDefaultShadowSubview {
    self.shadowSubview = [[[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, self.frame.size.width, self.frame.size.height)] autorelease];

    CALayer *shadowLayer = [CALayer layer];
    shadowLayer.backgroundColor = self.backgroundColor.CGColor;
    shadowLayer.shadowOffset = CGSizeMake(0, 3);
    shadowLayer.shadowRadius = 5.0;
    shadowLayer.shadowColor = [UIColor blackColor].CGColor;
    shadowLayer.shadowOpacity = 0.8;

    shadowLayer.frame = self.shadowSubview.frame;

    [self.shadowSubview.layer addSublayer:shadowLayer];

    self.shadowSubview.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    [self addSubview:self.shadowSubview];
    [self sendSubviewToBack:self.shadowSubview];
}

By this

- (void)addDefaultShadowSubview {
    self.shadowSubview = [[[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, self.frame.size.width, self.frame.size.height)] autorelease];

    CALayer *self.shadowSubview.layer = [CALayer layer];
    self.shadowSubview.layer.backgroundColor = self.backgroundColor.CGColor;
    self.shadowSubview.layer.shadowOffset = CGSizeMake(0, 3);
    self.shadowSubview.layer.shadowRadius = 5.0;
    self.shadowSubview.layer.shadowColor = [UIColor blackColor].CGColor;
    self.shadowSubview.layer.shadowOpacity = 0.8;
}

UIView: How to animate CALayer frame with shadow?

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