I have a UIView with a shadow and a UIImageView subview.
I want to resize the view when the iPad is rotated and I'm trying to do this in the willRotateToInterfaceOrientation callback.
If I set the shadow on the UIView in the basic way the rotation is very choppy; so I'd like some suggestions from others on how to set the shadow setting layer.shadowPath.
I have tried animating the frame size change using [UIView animateWithDuration:animations] and setting the new shadowPath in the same block, but the shadow path snaps to the new size.
And if I don't change the layer's shadowPath in the animations block, it doesn't change.
From a few searches I've done, animating changes to layer properties need to be done with a CABasicAnimation.
So I think the question may be "how do I animate a UIView's frame size and layer change simultaneously?"
There's a bit more code than one would hope but something like this should work.
CGFloat animationDuration = 5.0;
// Create the CABasicAnimation for the shadow
CABasicAnimation *shadowAnimation = [CABasicAnimation animationWithKeyPath:#"shadowPath"];
shadowAnimation.duration = animationDuration;
shadowAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; // Match the easing of the UIView block animation
shadowAnimation.fromValue = (id)self.shadowedView.layer.shadowPath;
// Animate the frame change on the view
[UIView animateWithDuration:animationDuration
delay:0.0f
options:UIViewAnimationCurveEaseInOut
animations:^{
self.shadowedView.frame = CGRectMake(self.shadowedView.frame.origin.x,
self.shadowedView.frame.origin.y,
self.shadowedView.frame.size.width * 2.,
self.shadowedView.frame.size.height * 2);
} completion:nil];
// Set the toValue for the animation to the new frame of the view
shadowAnimation.toValue = (id)[UIBezierPath bezierPathWithRect:self.shadowedView.bounds].CGPath;
// Add the shadow path animation
[self.shadowedView.layer addAnimation:shadowAnimation forKey:#"shadowPath"];
// Set the new shadow path
self.shadowedView.layer.shadowPath = [UIBezierPath bezierPathWithRect:self.shadowedView.bounds].CGPath;
Related
In a UIView animation for a view, you can animate its subviews being laid out by including UIViewAnimationOptionLayoutSubviews in the options parameter of [UIView animateWithDuration:delay:options:animations:completion:]. However, I cannot find a way to animate it laying out its sublayers when they are not some view's backing layer; they would just jump into place to match the new bounds of the view. Since I'm working with layers and not views, it seems like I have to use Core Animation instead of UIView animation, but I don't know how (and when) to do this such that the layer animation would match up to the view animation.
That's my basic question. Read more if you want to know the concrete thing I'm trying to accomplish.
I've created a view with a dotted border by adding a CAShapeLayer to the view's layer (see this stackoverflow question: Dashed line border around UIView). I adjust the path of the CAShapeLayer to match the bounds of the view in layoutSubviews.
This works, but there is one cosmetic issue: when the view's bounds is animated in a UIView animation (like during rotation), the dotted border jumps to the new bounds of the view instead of smoothly animating to it as the view animates its bounds. That is, the right and bottom parts of the dotted border do not respectively stay hugged to the right and bottom parts of the view as the view animates. How can I get the dotted border from the CAShapeLayer to animate alongside the view as it animates its bounds?
What I'm doing so far is attaching a CABasicAnimation to the CAShapeLayer:
- (void)layoutSubviews
{
[super layoutSubviews];
self.borderLayer.path = [UIBezierPath bezierPathWithRect:self.bounds].CGPath;
self.borderLayer.frame = self.bounds;
CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:#"path"];
[self.borderLayer addAnimation:pathAnimation forKey:nil];
}
This does cause the dotted border to animate, but it does not have the right timing function and animation duration to match the view animation. Also, sometimes, we don't want the dotted border to animate like, when the view first does layout, the border should not animate from some old path to the new correct path; it should just appear.
You might have found the answer already, but I also faced similar problems recently, since solved it, I will post the answer.
In - layoutSubViews method, you can get current UIView animation as backing layer's CAAnimation with - animationForKey: method.
Using this, You can implement - layoutSubviews like:
- (void)layoutSubviews {
[super layoutSubviews];
// get current animation for bounds
CAAnimation *anim = [self.layer animationForKey:#"bounds"];
[CATransaction begin];
if(anim) {
// animating, apply same duration and timing function.
[CATransaction setAnimationDuration:anim.duration];
[CATransaction setAnimationTimingFunction:anim.timingFunction];
CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:#"path"];
[self.borderLayer addAnimation:pathAnimation forKey:#"path"];
}
else {
// not animating, we should disable implicit animations.
[CATransaction disableActions];
}
self.borderLayer.path = [UIBezierPath bezierPathWithRect:self.bounds].CGPath;
self.borderLayer.frame = self.bounds;
[CATransaction commit];
}
I'm trying to animate a custom UIView's bounds while also keeping its layer the same size as its parent view. To do that, I'm trying to animate the layers bounds alongside its parent view. I need the layer to call drawLayer:withContext AS its animating so my custom drawing will change size correctly along with the bounds.
drawLayer is called correctly and draws correctly before I start the animation. But I can't get the layer to call its drawLayer method on EACH step of the bounds animation. Instead, it just calls it ONCE, jumping immediately to the "end bounds" at the final frame of the animation.
// self.bg is a property pointing to my custom UIView
self.bg.layer.needsDisplayOnBoundsChange = YES;
self.bg.layer.mask.needsDisplayOnBoundsChange = YES;
[UIView animateWithDuration:2 delay:0 options:UIViewAnimationOptionCurveEaseOut|UIViewAnimationOptionAutoreverse|UIViewAnimationOptionRepeat animations:^{
[CATransaction begin];
self.bg.layer.bounds = bounds;
self.bg.layer.mask.bounds = bounds;
[CATransaction commit];
self.bg.bounds = bounds;
} completion:nil];
Why doesn't the bounds report a change AS its animating (not just the final frame)? What am I doing wrong?
This might or might not help...
Many people are unaware that Core Animation has a supercool feature that allows you to define your own layer properties in such a way that they can be animated. An example I use is to give a CALayer subclass a thickness property. When I animate it with Core Animation...
CABasicAnimation* ba = [CABasicAnimation animationWithKeyPath:#"thickness"];
ba.toValue = #10.0f;
ba.autoreverses = YES;
[lay addAnimation:ba forKey:nil];
...the effect is that drawInContext: or drawLayer:... is called repeatedly throughout the animation, allowing me to change repeatedly the way the layer is drawn in accordance with its current thickness property value at each moment (an intermediate value in the course of the animation).
It seems to me that that might be the sort of thing you're after. If so, you can find a working downloadable example here:
https://github.com/mattneub/Programming-iOS-Book-Examples/tree/master/ch17p498customAnimatableProperty
Discussion (from my book) here:
http://www.apeth.com/iOSBook/ch17.html#_making_a_property_animatable
This is because the layer you are drawing to is not the same layer as the one displayed on the screen.
When you animate a layer property it will immediately be set to its final value in the model layer, (as you have noticed), and the actual animation is done in the presentation layer.
You can access the presentation layer and see the actual values of the animated properties:
CALayer *presentationLayer = (CALayer *)[self.bg.layer presentationLayer];
...
Since you haven't provided your drawLayer:withContext method, it's unclear what you want to draw during the animation, but if you want to animate custom properties, here is a good tutorial for doing that.
Firstly, the layer of a layer backed (or hosting) view is always resized to fit the bounds of its parent view. If you set the view to be the layers delegate then the view will receive drawLayer:inContext: at each frame. Of course you must ensure that If your layer has needsDisplayOnBoundsChange == YES.
Here is an example (on the Mac) of resizing a window, which then changes the path of the underlying layer.
// My Nib contains one view and one button.
// The view has a MPView class and the button action is resizeWindow:
#interface MPView() {
CAShapeLayer *_hostLayer;
CALayer *_outerLayer;
CAShapeLayer *_innerLayer;
}
#end
#implementation MPView
- (void)awakeFromNib
{
[CATransaction begin];
[CATransaction setDisableActions:YES];
_hostLayer = [CAShapeLayer layer];
_hostLayer.backgroundColor = [NSColor blackColor].CGColor;
_hostLayer.borderColor = [NSColor redColor].CGColor;
_hostLayer.borderWidth = 2;
_hostLayer.needsDisplayOnBoundsChange = YES;
_hostLayer.delegate = self;
_hostLayer.lineWidth = 4;
_hostLayer.strokeColor = [NSColor greenColor].CGColor;
_hostLayer.needsDisplayOnBoundsChange = YES;
self.layer = _hostLayer;
self.wantsLayer = YES;
[CATransaction commit];
[self.window setFrame:CGRectMake(100, 100, 200, 200) display:YES animate:NO];
}
- (void) drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx
{
if (layer == _hostLayer) {
CGSize size = layer.bounds.size;
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, NULL, 0, 0);
CGPathAddLineToPoint(path, NULL, size.width, size.height);
_hostLayer.path = path;
CGPathRelease(path);
}
}
- (IBAction)resizeWindow:(id)sender
{
[self.window setFrame:CGRectMake(100, 100, 1200, 800) display:YES animate:YES];
}
#end
Image showing what I would like to achieve
I want to move a view animately from a position to a new postion. If update the layer position of a view, I think the view will animately move to the new position, which is implicit animation I guess, but there's no animation, why?
- (IBAction)startAnimation:(id)sender {
CGPoint position = self.imageView.layer.position;
position.y += 90;
self.imageView.layer.position = position;
}
Implicit animations only happen for standalone layer, not layers backing up views. You will need to explicitly animate the position. You can either do it by creating a CABasicAnimation for the position and add it to the layer or use UIView animations to animate the center property of the view.
Creating an explicit animation
CABasicAnimation *move = [CABasicAnimation animationWithKeyPath:#"position"];
move.toValue = [NSValue valueWithCGPoint:newPoint];
move.duration = 0.3;
[self.imageView.layer addAnimation:move forKey:#"myMoveAnimation"];
Using UIView animations
[UIView animateWithDuration:0.3 animations:^{
self.imageView.center = newCenter;
}];
I'm trying to create a UIView which shows a semitransparent circle with an opaque border inside its bounds. I want to be able to change the bounds in two ways - inside a -[UIView animateWithDuration:animations:] block and in a pinch gesture recogniser action which fires several times a second. I've tried three approaches based on answers elsewhere on SO, and none are suitable.
Setting the corner radius of the view's layer in layoutSubviews gives smooth translations, but the view doesn't stay circular during animations; it seems that cornerRadius isn't animatable.
Drawing the circle in drawRect: gives a consistently circular view, but if the circle gets too big then resizing in the pinch gesture gets choppy because the device is spending too much time redrawing the circle.
Adding a CAShapeLayer and setting its path property in layoutSublayersOfLayer, which doesn't animate inside UIView animations since path isn't implicitly animatable.
Is there a way for me to create a view which is consistently circular and smoothly resizable? Is there some other type of layer I could use to take advantage of the hardware acceleration?
UPDATE
A commenter has asked me to expand on what I mean when I say that I want to change the bounds inside a -[UIView animateWithDuration:animations:] block. In my code, I have a view which contains my circle view. The circle view (the version that uses cornerRadius) overrides -[setBounds:] in order to set the corner radius:
-(void)setBounds:(CGRect)bounds
{
self.layer.cornerRadius = fminf(bounds.size.width, bounds.size.height) / 2.0;
[super setBounds:bounds];
}
The bounds of the circle view are set in -[layoutSubviews]:
-(void)layoutSubviews
{
// some other layout is performed and circleRadius and circleCenter are
// calculated based on the properties and current size of the view.
self.circleView.bounds = CGRectMake(0, 0, circleRadius*2, circleRadius*2);
self.circleView.center = circleCenter;
}
The view is sometimes resized in animations, like so:
[UIView animateWithDuration:0.33 animations:^(void) {
myView.frame = CGRectMake(x, y, w, h);
[myView setNeedsLayout];
[myView layoutIfNeeded];
}];
but during these animations, if I draw the circle view using a layer with a cornerRadius, it goes funny shapes. I can't pass the animation duration in to layoutSubviews so I need to add the right animation within -[setBounds].
As the section on Animations in the "View Programming Guide for iOS" says
Both UIKit and Core Animation provide support for animations, but the level of support provided by each technology varies. In UIKit, animations are performed using UIView objects
The full list of properties that you can animate using either the older
[UIView beginAnimations:context:];
[UIView setAnimationDuration:];
// Change properties here...
[UIView commitAnimations];
or the newer
[UIView animateWithDuration:animations:];
(that you are using) are:
frame
bounds
center
transform (CGAffineTransform, not the CATransform3D)
alpha
backgroundColor
contentStretch
What confuses people is that you can also animate the same properties on the layer inside the UIView animation block, i.e. the frame, bounds, position, opacity, backgroundColor.
The same section goes on to say:
In places where you want to perform more sophisticated animations, or animations not supported by the UIView class, you can use Core Animation and the view’s underlying layer to create the animation. Because view and layer objects are intricately linked together, changes to a view’s layer affect the view itself.
A few lines down you can read the list of Core Animation animatable properties where you see this one:
The layer’s border (including whether the layer’s corners are rounded)
There are at least two good options for achieving the effect that you are after:
Animating the corner radius
Using a CAShapeLayer and animating the path
Both of these require that you do the animations with Core Animation. You can create a CAAnimationGroup and add an array of animations to it if you need multiple animations to run as one.
Update:
Fixing things with as few code changes as possible would be done by doing the corner radius animation on the layer at the "same time" as the other animations. I put quotations marks around same time since it is not guaranteed that animations that are not in the same group will finish at exactly the same time. Depending on what other animations you are doing it might be better to use only basic animations and animations groups. If you are applying changes to many different views in the same view animation block then maybe you could look into CATransactions.
The below code animates the frame and corner radius much like you describe.
UIView *circle = [[UIView alloc] initWithFrame:CGRectMake(30, 30, 100, 100)];
[[circle layer] setCornerRadius:50];
[[circle layer] setBorderColor:[[UIColor orangeColor] CGColor]];
[[circle layer] setBorderWidth:2.0];
[[circle layer] setBackgroundColor:[[[UIColor orangeColor] colorWithAlphaComponent:0.5] CGColor]];
[[self view] addSubview:circle];
CGFloat animationDuration = 4.0; // Your duration
CGFloat animationDelay = 3.0; // Your delay (if any)
CABasicAnimation *cornerRadiusAnimation = [CABasicAnimation animationWithKeyPath:#"cornerRadius"];
[cornerRadiusAnimation setFromValue:[NSNumber numberWithFloat:50.0]]; // The current value
[cornerRadiusAnimation setToValue:[NSNumber numberWithFloat:10.0]]; // The new value
[cornerRadiusAnimation setDuration:animationDuration];
[cornerRadiusAnimation setBeginTime:CACurrentMediaTime() + animationDelay];
// If your UIView animation uses a timing funcition then your basic animation needs the same one
[cornerRadiusAnimation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
// This will keep make the animation look as the "from" and "to" values before and after the animation
[cornerRadiusAnimation setFillMode:kCAFillModeBoth];
[[circle layer] addAnimation:cornerRadiusAnimation forKey:#"keepAsCircle"];
[[circle layer] setCornerRadius:10.0]; // Core Animation doesn't change the real value so we have to.
[UIView animateWithDuration:animationDuration
delay:animationDelay
options:UIViewAnimationOptionCurveEaseInOut
animations:^{
[[circle layer] setFrame:CGRectMake(50, 50, 20, 20)]; // Arbitrary frame ...
// You other UIView animations in here...
} completion:^(BOOL finished) {
// Maybe you have your completion in here...
}];
With many thanks to David, this is the solution I found. In the end what turned out to be the key to it was using the view's -[actionForLayer:forKey:] method, since that's used inside UIView blocks instead of whatever the layer's -[actionForKey] returns.
#implementation SGBRoundView
-(CGFloat)radiusForBounds:(CGRect)bounds
{
return fminf(bounds.size.width, bounds.size.height) / 2;
}
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
self.backgroundColor = [UIColor clearColor];
self.opaque = NO;
self.layer.backgroundColor = [[UIColor purpleColor] CGColor];
self.layer.borderColor = [[UIColor greenColor] CGColor];
self.layer.borderWidth = 3;
self.layer.cornerRadius = [self radiusForBounds:self.bounds];
}
return self;
}
-(void)setBounds:(CGRect)bounds
{
self.layer.cornerRadius = [self radiusForBounds:bounds];
[super setBounds:bounds];
}
-(id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event
{
id<CAAction> action = [super actionForLayer:layer forKey:event];
if ([event isEqualToString:#"cornerRadius"])
{
CABasicAnimation *boundsAction = (CABasicAnimation *)[self actionForLayer:layer forKey:#"bounds"];
if ([boundsAction isKindOfClass:[CABasicAnimation class]] && [boundsAction.fromValue isKindOfClass:[NSValue class]])
{
CABasicAnimation *cornerRadiusAction = [CABasicAnimation animationWithKeyPath:#"cornerRadius"];
cornerRadiusAction.delegate = boundsAction.delegate;
cornerRadiusAction.duration = boundsAction.duration;
cornerRadiusAction.fillMode = boundsAction.fillMode;
cornerRadiusAction.timingFunction = boundsAction.timingFunction;
CGRect fromBounds = [(NSValue *)boundsAction.fromValue CGRectValue];
CGFloat fromRadius = [self radiusForBounds:fromBounds];
cornerRadiusAction.fromValue = [NSNumber numberWithFloat:fromRadius];
return cornerRadiusAction;
}
}
return action;
}
#end
By using the action that the view provides for the bounds, I was able to get the right duration, fill mode and timing function, and most importantly delegate - without that, the completion block of UIView animations didn't run.
The radius animation follows that of the bounds in almost all circumstances - there are a few edge cases that I'm trying to iron out, but it's basically there. It's also worth mentioning that the pinch gestures are still sometimes jerky - I guess even the accelerated drawing is still costly.
Starting in iOS 11, UIKit animates cornerRadius if you change it inside an animation block.
The path property of a CAShapeLayer isn't implicitly animatable, but it is animatable. It should be pretty easy to create a CABasicAnimation that changes the size of the circle path. Just makes sure that the path has the same number of control points (e.g. changing the radius of a full-circle arc.) If you change the number of control points, things get really strange. "Results are undefined", according to the documentaiton.
I have a very simple UIView animation, which causes my view to "throb":
[UIView animateWithDuration:0.2 delay:0.0f options:UIViewAnimationOptionAllowUserInteraction+UIViewAnimationOptionRepeat+UIViewAnimationOptionAutoreverse animations:^{
CGAffineTransform transf = CGAffineTransformScale(self.view.transform, 1.05f, 1.05f);
[self.view setTransform:transf];
} completion:nil];
At some point the user hits a button to cancel the animation, and apply a new transform.
[self.view.layer removeAllAnimations];
[self.view setTransform:aNewTransform];
I'd like it to reset to it's original transform, but instead it's getting increased in size by 5%.
Edit: I tried adding a completion block that resets the transform to it's original position. This works, but causes the transform I run immediately after to be trampled... the completion block gets run AFTER I apply aNewTransform.
Edit 2: I found a solution, using CABasicAnimation, instead of UIView animations. I would still be interested if anybody found a solution using UIView animations... I like the block-based interface better. This also only works, because I happen to be keeping track of my scale value separate from the one applied to the view. Everything that changes the scale uses a method that also changes self.scale
My replacement animation:
CABasicAnimation *basicAnimation = [CABasicAnimation animationWithKeyPath:#"transform.scale"];
basicAnimation.toValue = [NSNumber numberWithFloat:self.scale*1.05f];
basicAnimation.fromValue = [NSNumber numberWithFloat:self.scale];
basicAnimation.autoreverses = YES;
basicAnimation.duration = 0.2;
basicAnimation.repeatCount = HUGE_VALF;
[self.view.layer addAnimation:basicAnimation forKey:#"Throb"];
Before starting a new animation on an existing view, you can reset the view if any of these attributes were previously altered:
// first, don't forget to stop ongoing animations for the view
[theView.layer removeAllAnimations];
// if the view was hidden
theView.hidden = NO;
// if you applied a transformation e.g. translate, scale, rotate..., reset to identity
theView.transform = CGAffineTransformIdentity;
// if you changed the anchor point, this will reset it to the center of the view
theView.layer.anchorPoint = CGPointMake(0.5, 0.5);
// if you changed the alpha, this will reset it to visible
theView.alpha = 1.;
Try putting the line
[self.view setTransform:aNewTransform];
in the completion block.