iOs-coders!
This code to animate the little red square to drawing big sign "8" on the UIView. First an upper ring (animSequence1 = 5 sec), then right away a lower ring (animSequence2 = another 5 sec).
No delay needed!
But I stucked on strange delay (about 1 sec) between two sequential animations. Whence did this delay come from?!?
Code:
- (void)drawRect:(CGRect)drawRect {
CGContextRef context = UIGraphicsGetCurrentContext();
drawRect = CGRectMake(0, 0, 320, 320);
CGContextSetFillColorWithColor(context, [UIColor blueColor].CGColor;);
CGContextFillRect(context, drawRect);
// Little red square
CALayer *layerTest;
layerTest = [CALayer layer];
layerTest.bounds = CGRectMake(0, 0, 20, 20);
layerTest.anchorPoint = CGPointMake(0, 0);
layerTest.backgroundColor = [UIColor redColor].CGColor;
[[self layer] addSublayer:layerTest];
// Upper ring
CAKeyframeAnimation *animSequence1;
animSequence1 = [CAKeyframeAnimation animationWithKeyPath:#"position"];
animSequence1.fillMode = kCAFillModeForwards;
animSequence1.removedOnCompletion = NO;
animSequence1.autoreverses = NO;
animSequence1.repeatCount = 0;
animSequence1.duration = 5.0;
animSequence1.beginTime = 0.0;
animSequence1.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(200, 120) radius:80 startAngle:DEG_TO_RAD(90) endAngle:DEG_TO_RAD(450) clockwise:YES].CGPath;
animSequence1.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
// Lower ring
CAKeyframeAnimation *animSequence2;
animSequence2 = [CAKeyframeAnimation animationWithKeyPath:#"position"];
animSequence2.fillMode = kCAFillModeForwards;
animSequence2.removedOnCompletion = NO;
animSequence2.autoreverses = NO;
animSequence2.repeatCount = 0;
animSequence2.duration = 5.0;
animSequence2.beginTime = 5.0;
animSequence2.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(200, 280) radius:80 startAngle:DEG_TO_RAD(-90) endAngle:DEG_TO_RAD(-450) clockwise:NO].CGPath;
animSequence2.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
// A sequence of animations
CAAnimationGroup *animGroup;
layerTest.position = CGPointMake(200, 200);
animGroup = [CAAnimationGroup animation];
animGroup.duration = 10.0;
animGroup.animations = [NSArray arrayWithObjects:animSequence1, animSequence2, nil];
[layerTest addAnimation:animGroup forKey:nil];
}
Also I tried make it without CAAnimationGroup.
Set up [animSequence1 setDelegate:self]; for first CAKeyframeAnimation (animSequence1), and then start second CAKeyframeAnimation (animSequence2) by (void)animationDidStop.
It worked same, but this strange delay (about 1 sec) between two animations no dissapear!
QUESTION: How to remove strange delay between two sequential CAKeyframeAnimation animations? No delay needed!
Don’t create layers or animations in -drawRect:—you don’t have a whole lot of control over when it gets called, so you’re going to end up with multiple layerTests added to your view, all trying to animate separately. Create the layer / animation in an initializer, or in response to some user interaction.
I would also advise getting rid of your fillMode and removedOnCompletion settings on animSequence1; once animSequence2 starts, you’re effectively asking CA to run two non-additive animations once on the same property. Not sure whether the behavior for that is well-defined, but it’s another place the weirdness could be coming from.
Related
When animating the position or bounds of a CALayer with a CAKeyframeAnimation (or probably with any other CAAnimation) and exporting a full HD 1920x1080 or HDReady 1280x720 movie using AVAssetExport, the animation in the resulting movie become jumpy.
If the resolution is the same as the native iPhone screen size, the animation stays fluid.
CAAction seem to have no impact on the result. Using a path instead of values doesn't change anything either.
Here's a short short video showing the issue.
My guess is I should need to interpolate more frequently or redraw more (or less) frequently the layer during the animation. Any idea to act on those parameters ?
The layer
CALayer * layer = [CALayer layer];
layer.anchorPoint = CGPointZero;
layer.frame = self.creator.animationLayer.bounds;
layer.backgroundColor = [UIColor clearColor].CGColor;
layer.opacity = 0.f;
layer.contentsGravity = kCAGravityResizeAspectFill;
layer.contents = (__bridge id)image;
The Animation
CAKeyframeAnimation * contentRectAnimation =
[CAKeyframeAnimation animationWithKeyPath:#"position"];
contentRectAnimation.removedOnCompletion = NO;
contentRectAnimation.beginTime = beginTime;
contentRectAnimation.duration = totalDuration;
contentRectAnimation.fillMode = kCAFillModeBoth;
contentRectAnimation.keyTimes = keyTimes;
contentRectAnimation.values = positions;
contentRectAnimation.timingFunctions = timingFunctions;
[self.currentAnimationLayer addAnimation:contentRectAnimation
forKey:#"position"];
CAKeyframeAnimation * boundsAnimation =
[CAKeyframeAnimation animationWithKeyPath:#"bounds"];
boundsAnimation.removedOnCompletion = NO;
boundsAnimation.beginTime = beginTime;
boundsAnimation.duration = totalDuration;
boundsAnimation.fillMode = kCAFillModeBoth;
boundsAnimation.keyTimes = keyTimes;
boundsAnimation.values = bounds;
boundsAnimation.timingFunctions = timingFunctions;
[self.currentAnimationLayer addAnimation:boundsAnimation
forKey:#"bounds"];
I can draw points with code below, but I need to draw every point one by one with animation. When I try this, all points appear on the screen only after the for loop ends.
I did some research but I could not figure out why these points are not drawing one by one in the for loop. singerData is an array which has x values of points.
-(void)drawDotGraphForUser
{
UIView *viewAnimationUser = [[UIView alloc]init];
viewAnimationUser.frame = CGRectMake(0, 0, 320, 100);
for (int i = 0; i<singerPitchDataSize; i++)
{
CALayer *layer = [CALayer layer];
NSAssert1(layer != nil, #"failed to create CALayer #%i", i);
layer.backgroundColor = [UIColor colorWithRed:0 green:0 blue:1 alpha:1.0].CGColor;
layer.frame = CGRectMake(i+1, singerData[i], 1.0, 1.0);
NSLog(#"GraphUser= %d=%f",i,singerData[i]);
NSLog(#"MSprites=%#",mSprites[i]);
CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
pathAnimation.duration = 5;
pathAnimation.fromValue = [NSNumber numberWithInt:0];
pathAnimation.toValue = [NSNumber numberWithInt:singerPitchDataSize];
[layer addAnimation:pathAnimation forKey:#"strokeEnd"];
[viewAnimationUser.layer addSublayer:layer];
[self.view addSubview:viewAnimationUser];
}
}
These are all appearing to be happening at the same time because your animations are being sent to another thread automatically extremely quickly. If you want them to appear one by one you will need to send them to add them to the subview slower by adding a timer at the end of your function or you will need to listen for the animation to end to trigger the next one.
I am a bit of a beginner with animations and have been experimenting with CoreAnimation for a couple of days. Feel free to warn me if this question does not make sense, but I'm trying to achieve the following. I have three objects:
one should be an image, moving according to a given pattern
one should be an UIImage that swaps two images
one should be a text (CATextLayer?) whose content changes
The three actions should happen in sync.
As an example, think about a programme showing a sinusoid function, like in a ECG, oscillating between -1 and +1: the first image would then move according to the current value (-1, -0.9, -0.8, ... 0, +0.1, +0.2, ... 1), the swap image would show "+" for positive values and "-" for negative values, and the text would alternate between "Positive" and "Negative".
I've tried with CAAnimationGroup but I'm clearly missing something. Some code:
{
// image that moves
CALayer *img1 = [CALayer layer];
img1.bounds = CGRectMake(0, 0, 20, 20);
img1.position = CGPointMake(x1,y1);
UIImage *img1Image = [UIImage imageNamed:#"image.png"];
img1.contents = (id)img1Image.CGImage;
// image that changes
CALayer *swap = [CALayer layer];
swap.bounds = CGRectMake(0, 0, 30, 30);
swap.position = CGPointMake(x2,y2);
NSString* nameswap = #"img_swap_1.png"
UIImage *swapImg = [UIImage imageNamed:nameswap];
// text
CATextLayer *text = [CATextLayer layer];
text.bounds = CGRectMake(0, 0, 100, 100);
text.position = CGPointMake(x3,y3);
text.string = #"Text";
// create animations
CGFloat duration = 0.2;
CGFloat totalDuration = 0.0;
CGFloat start = 0;
NSMutableArray* animarray = [[NSMutableArray alloc] init];
NSMutableArray* swapanimarray = [[NSMutableArray alloc] init];
NSMutableArray* textanimarray = [[NSMutableArray alloc] init];
float prev_x = 0;
float prev_y = 0;
// I get my values for moving the object
for (NSDictionary* event in self.events) {
float actual_x = [[event valueForKey:#"x"] floatValue];
float actual_y = [[event valueForKey:#"y"] floatValue];
// image move animation
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:#"position"];
CGPoint startPt = CGPointMake(prev_x,prev_y);
CGPoint endPt = CGPointMake(actual_x, actual_y);
anim.duration = duration;
anim.fromValue = [NSValue valueWithCGPoint:startPt];
anim.toValue = [NSValue valueWithCGPoint:endPt];
anim.beginTime = start;
anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
[animarray addObject:anim];
// image swap animation
CABasicAnimation *swapanim = [CABasicAnimation animationWithKeyPath:#"contents"];
swapanim.duration = duration;
swapanim.beginTime = start;
NSString* swapnamefrom = [NSString stringWithFormat:#"%#.png", prev_name];
NSString* swapnameto = [NSString stringWithFormat:#"%#.png", current_name];
UIImage *swapFromImage = [UIImage imageNamed:swapnamefrom];
UIImage *swapToImage = [UIImage imageNamed:swapnameto];
swapanim.fromValue = (id)(swapFromImage.CGImage);
swapanim.toValue = (id)(swapToImage.CGImage);
swapanim.fillMode = kCAFillModeForwards;
swapanim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
[swapanimarray addObject:swapanim];
//text animation
CABasicAnimation *textanim = [CABasicAnimation animationWithKeyPath:#"contents"];
textanim.duration = duration;
textanim.fromValue = #"Hey";
textanim.toValue = #"Hello";
textanim.beginTime = start;
[textanimarray addObject:textanim];
// final time settings
prev_x = actual_x;
prev_y = actual_y;
start = start + duration;
totalDuration = start + duration;
}
}
CAAnimationGroup* group = [CAAnimationGroup animation];
[group setDuration:totalDuration];
group.removedOnCompletion = NO;
group.fillMode = kCAFillModeForwards;
[group setAnimations:animarray];
CAAnimationGroup* swapgroup = [CAAnimationGroup animation];
[swapgroup setDuration:totalDuration];
swapgroup.removedOnCompletion = NO;
swapgroup.fillMode = kCAFillModeForwards;
[swapgroup setAnimations:swapanimarray];
CAAnimationGroup* textgroup = [CAAnimationGroup animation];
[textgroup setDuration:totalDuration];
textgroup.removedOnCompletion = NO;
textgroup.fillMode = kCAFillModeForwards;
[textgroup setAnimations:textanimarray];
[ball addAnimation:group forKey:#"position"];
[swap addAnimation:flaggroup forKey:#"position"];
[text addAnimation:textgroup forKey:#"contents"];
[self.layer addSublayer:ball];
[self.layer addSublayer:swap];
[self.layer addSublayer:text];
}
Now... the problems:
1) the swap image reverts to the original at every swap. So, if I swap A->B, I see it going from A to B in the expected duration time, but then reverting to A. I've read a number of threads on SO about this but couldn't get it to work.
2) changing the string of the text layer in a timed fashion... is this possible with this infrastructure? Basically, I'm trying to get the text and the swap image to change as soon as the first image moves, as described in the example.
3) setting the delegate for the CABasicAnimation doesn't have any effect, although it does for the CAAnimationGroup: as a result, you can't manage events like animationDidStop for every single animation, just for the whole group. Is there any alternative way to do so?
4) following from 3), is it possible, using CAAnimationGroup, to intercept the events to create a stop/start behaviour? Let's suppose I wanted to have play/stop buttons, and to resume the animation from exactly where I had left it?
As a conclusive question, I would simply like to know if anyone did something similar and, most importantly, if this way of doing things (using a CAAnimationGroup) is actually the way to go or if it's better to use CAKeyFrameAnimation or something else.
I managed to solve the problem, albeit with some workarounds.
1) The trick here is that
removedOnCompletion = NO;
fillMode = kCAFillModeForwards;
need to be assigned to every single animation, not to the CAAnimationGroup.
2) This requires a separate animation to be determined for the CATextLayer, and animating the "string" property. In this case, the code was right except for the "contents" key-value which should have been
[text addAnimation:textgroup forKey:#"contentAnimate"];
Alternatively, see point 3. The callback way of operation allows to change a label.text.
3) The only way to do this is to actually not use the CAAnimationGroup and set up a sequence of CABasicAnimation. The general schema is: create the first CABasicAnimation in a function, assign the delegate. In the animationDidStop method, add a callback to the function that creates the CABasicAnimation. This way, each animation will be created. At the same time, this allows to intercept and react to specific events within the animation.
-(void)performNextAnimation:(int)index {
// ... this gives for granted you have an object for #index ...
NSDictionary* thisEvent = [self.events objectAtIndex:index];
float prev_x = [thisEvent valueForKey:#"prev_x"];
float prev_y = [thisEvent valueForKey:#"prev_x"];
float actual_x = [thisEvent valueForKey:#"prev_x"];
float actual_y = [thisEvent valueForKey:#"prev_x"];
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:#"position"];
GPoint startPt = CGPointMake(prev_x,prev_y);
CGPoint endPt = CGPointMake(actual_x, actual_y);
anim.duration = 0.5;
anim.fromValue = [NSValue valueWithCGPoint:startPt];
anim.toValue = [NSValue valueWithCGPoint:endPt];
anim.beginTime = start;
[anim setDelegate:self];
anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
[object addAnimation:anim forKey:#"position"];
}
- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag {
// ... your conditions go here ...
// ... your actions go here ...
// e.g. set label.text
[self performNextAnimation];
}
4) Following from 3, this is not possible in CAAnimationGroup. Reading the docs, I would say that CAAnimationGroup is not intended to be used for sequences in which each event represents a step forward in time (for this you need to use CAKeyFrameAnimation or a sequence of CABasicAnimation with a callback function, as I did). CAAnimationGroup is intended for linked animation that should be executed on an all-or-nothing basis (similarly to CATransaction).
In another test of Key Frame animation I am combining moving a UIImageView (called theImage) along a bezier path and scaling larger it as it moves, resulting in a 2x larger image at the end of the path. My initial code to do this has these elements in it to kick off the animation:
UIImageView* theImage = ....
float scaleFactor = 2.0;
....
theImage.center = destination;
theImage.transform = CGAffineTransformMakeScale(1.0,1.0);
CABasicAnimation *resizeAnimation = [CABasicAnimation animationWithKeyPath:#"bounds.size"];
[resizeAnimation setToValue:[NSValue valueWithCGSize:CGSizeMake(theImage.image.size.height*scaleFactor, theImage.image.size.width*scaleFactor)]];
resizeAnimation.fillMode = kCAFillModeBackwards;
resizeAnimation.removedOnCompletion = NO;
CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:#"position"];
pathAnimation.path = [jdPath path].CGPath;
pathAnimation.fillMode = kCAFillModeBackwards;
pathAnimation.removedOnCompletion = NO;
CAAnimationGroup* group = [CAAnimationGroup animation];
group.animations = [NSArray arrayWithObjects:pathAnimation, resizeAnimation, nil];
group.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
group.removedOnCompletion = NO;
group.duration = duration;
group.delegate = self;
[theImage.layer addAnimation:group forKey:#"animateImage"];
Then, when the animation completes I want to retain the image at the larger size, so I implement:
- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag
{
theImage.transform = CGAffineTransformMakeScale(scaleFactor,scaleFactor);
}
This all works .. sort of. The problem is that at the end of the animation theImage flickers for a brief moment - just enough to make it look bad. I am guessing that this is the transition at the end of the animation where I set the transform to the new size.
In experimenting with this I tried a slightly different form of the above, but still got the same flicker:
CAKeyframeAnimation *resizeAnimation = [CAKeyframeAnimation animationWithKeyPath:#"transform"];
NSValue* startSizeKey = [NSValue valueWithCATransform3D:CATransform3DScale (theImage.layer.transform, 1.0, 1.0, 1.0)];
NSValue* endSizeKey = [NSValue valueWithCATransform3D:CATransform3DScale (theImage.layer.transform, scaleFactor, scaleFactor, 1.0)];
NSArray* sizeKeys = [NSArray arrayWithObjects:startSizeKey, endSizeKey, nil];
[resizeAnimation setValues:sizeKeys];
....
theImage.transform = CGAffineTransformMakeScale(scaleFactor,scaleFactor);
But when I ended the animation at the same size as the original, there was NO flicker:
CAKeyframeAnimation *resizeAnimation = [CAKeyframeAnimation animationWithKeyPath:#"transform"];
NSValue* startSizeKey = [NSValue valueWithCATransform3D:CATransform3DScale (theImage.layer.transform, 1.0, 1.0, 1.0)];
NSValue* middleSizeKey = [NSValue valueWithCATransform3D:CATransform3DScale (theImage.layer.transform, scaleFactor, scaleFactor, 1.0)];
NSValue* endSizeKey = [NSValue valueWithCATransform3D:CATransform3DScale (theImage.layer.transform, 1.0, 1.0, 1.0)];
NSArray* sizeKeys = [NSArray arrayWithObjects:startSizeKey, middleSizeKey, endSizeKey, nil];
[resizeAnimation setValues:sizeKeys];
....
theImage.transform = CGAffineTransformMakeScale(1.0,1.0);
So my big question is how can I animate this image without the flicker, and end up with a different size at the end of the animation?
Edit March 2nd
My initial tests were with scaling the image up. I just tried scaling it down (IE scaleFactor = 0.4) and the flickering was a lot more visible, and a lot more obvious as to what I am seeing. This was the sequence of events:
Original sized image is painted on the screen at the starting location.
As the image moves along the path it shrinks smoothly.
The fully shrunk image arrives at the end of the path.
The image is then painted at its original size.
The image is finally painted at its shrunken size.
So it seems to be step 4 that is the flickering that I am seeing.
Edit March 22
I have just uploaded to GitHub a demo project that shows off the moving of an object along a bezier path. The code can be found at PathMove
I also wrote about it in my blog at Moving objects along a bezier path in iOS
It can be tricky to animate a view's layer using Core Animation. There are several things that make it confusing:
Setting an animation on a layer doesn't change the layer's properties. Instead, it changes the properties of a “presentation layer” that replaces the original “model layer” on the screen as long as the animation is applied.
Changing a layer's property normally adds an implicit animation to the layer, with the property name as the animation's key. So if you want to explicitly animate a property, you usually want to set the property to its final value, then add an animation whose key is the property name, to override the implicit animation.
A view normally disables implicit animations on its layer. It also mucks around with its layer's properties in other somewhat mysterious ways.
Also, it's confusing that you animate the view's bounds to scale it up, but then switch to a scale transformation at the end.
I think the easiest way to do what you want is to use the UIView animation methods as much as possible, and only bring in Core Animation for the keyframe animation. You can add the keyframe animation to the view's layer after you've let UIView add its own animation, and your keyframe animation will override the animation added by UIView.
This worked for me:
- (IBAction)animate:(id)sender {
UIImageView* theImage = self.imageView;
CGFloat scaleFactor = 2;
NSTimeInterval duration = 1;
UIBezierPath *path = [self animationPathFromStartingPoint:theImage.center];
CGPoint destination = [path currentPoint];
[UIView animateWithDuration:duration animations:^{
// UIView will add animations for both of these changes.
theImage.transform = CGAffineTransformMakeScale(scaleFactor, scaleFactor);
theImage.center = destination;
// Prepare my own keypath animation for the layer position.
// The layer position is the same as the view center.
CAKeyframeAnimation *positionAnimation = [CAKeyframeAnimation animationWithKeyPath:#"position"];
positionAnimation.path = path.CGPath;
// Copy properties from UIView's animation.
CAAnimation *autoAnimation = [theImage.layer animationForKey:#"position"];
positionAnimation.duration = autoAnimation.duration;
positionAnimation.fillMode = autoAnimation.fillMode;
// Replace UIView's animation with my animation.
[theImage.layer addAnimation:positionAnimation forKey:positionAnimation.keyPath];
}];
}
CAAnimations will flicker at the end if the terminal state was assigned in such a way that it itself created an implicit animation. Keep in mind CAAnimations are temporary adjustments of an object properties for the purposes of visualizing transition. When the animation done, if the layer's state is still the original starting state, that is what is going to be displayed ever so temporarily until you set the final layer state, which you do in your animationDidStop: method.
Furthermore, your animation is adjusting the bounds.size property of your layer, so you should similarly set your final state rather than using the transform adjustment as your final state. You could also use the transform property as the animating property in the animation instead of bounds.size.
To remedy this, immediately after assigning the animation, change the layer's permeant state to your desired terminal state so that when the animation completes there will be no flicker, but do so in such a manner to no trigger an implicit animation before the animation begins. Specifically, in your case you should do this at the end of your animation set up:
UIImageView* theImage = ....
float scaleFactor = 2.0;
....
theImage.center = destination;
theImage.transform = CGAffineTransformMakeScale(1.0,1.0);
CGSize finalSize = CGSizeMake(theImage.image.size.height*scaleFactor, theImage.image.size.width*scaleFactor);
CABasicAnimation *resizeAnimation = [CABasicAnimation animationWithKeyPath:#"bounds.size"];
[resizeAnimation setToValue:[NSValue valueWithCGSize:finalSize]];
resizeAnimation.fillMode = kCAFillModeBackwards;
resizeAnimation.removedOnCompletion = NO;
CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:#"position"];
pathAnimation.path = [jdPath path].CGPath;
pathAnimation.fillMode = kCAFillModeBackwards;
pathAnimation.removedOnCompletion = NO;
CAAnimationGroup* group = [CAAnimationGroup animation];
group.animations = [NSArray arrayWithObjects:pathAnimation, resizeAnimation, nil];
group.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
group.removedOnCompletion = NO;
group.duration = duration;
group.delegate = self;
[theImage.layer addAnimation:group forKey:#"animateImage"];
[CATransaction begin];
[CATransaction setDisableActions:YES];
theImage.bounds = CGRectMake( theImage.bounds.origin.x, theImage.bounds.origin.y, finalSize.width, finalSize.height );
[CATransaction commit];
and then remove the transform adjustment in your animationDidStop: method.
I was experimenting with some CAAnimations this week and was noticing that there was a flickering at the end of my animations. In particular, I would animation from a circle to a square, while changing the fillColor as well.
Each CAAnimation has a property called removedOnCompletion which defaults to YES. This means that the animation will disappear (i.e. transitions, scales, rotations, etc.) when the animation completes and you'll be left with the original layer.
Since you already have set your removedOnCompletion properties to NO, I would suggest trying to shift your execution of your animations to use CATransactions, instead of delegates and animationDidStop...
[CATransaction begin];
[CATransaction setDisableActions:YES];
[CATransaction setCompletionBlock: ^{ theImage.transform = ...}];
// ... CAAnimation Stuff ... //
[CATransaction commit];
You put the transaction's completion block call before you create your animations, as per:
http://zearfoss.wordpress.com/2011/02/24/core-animation-catransaction-protip/
The following is from one of my methods:
[CATransaction begin];
CABasicAnimation *animation = ...;
animation.fromValue = ...;
animation.toValue = ...;
[CATransaction setCompletionBlock:^ { self.shadowRadius = _shadowRadius; }];
[self addAnimation:animation forKey:#"animateShadowOpacity"];
[CATransaction commit];
And, I constructed this animation and it works fine for me with no glitches at the end:
The setup and trigger are custom methods I have in a window, and i trigger the animation on mousedown.
UIImageView *imgView;
UIBezierPath *animationPath;
-(void)setup {
canvas = (C4View *)self.view;
imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"img256.png"]];
imgView.frame = CGRectMake(0, 0, 128, 128);
imgView.center = CGPointMake(384, 128);
[canvas addSubview:imgView];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[UIImageView animateWithDuration:2.0f animations:^{
[CATransaction begin];
CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:#"position"];
pathAnimation.duration = 2.0f;
pathAnimation.calculationMode = kCAAnimationPaced;
animationPath = [UIBezierPath bezierPath];
[animationPath moveToPoint:imgView.center];
[animationPath addLineToPoint:CGPointMake(128, 512)];
[animationPath addLineToPoint:CGPointMake(384, 896)];
pathAnimation.path = animationPath.CGPath;
pathAnimation.fillMode = kCAFillModeForwards;
pathAnimation.removedOnCompletion = NO;
[imgView.layer addAnimation:pathAnimation forKey:#"animatePosition"];
[CATransaction commit];
CGFloat scaleFactor = 2.0f;
CGRect newFrame = imgView.frame;
newFrame.size.width *= scaleFactor;
newFrame.size.height *= scaleFactor;
newFrame.origin = CGPointMake(256, 0);
imgView.frame = newFrame;
imgView.transform = CGAffineTransformRotate(imgView.transform,90.0*M_PI/180);
}];
}
In iOS I'm trying to create the effect of an icon shrinking in size, and flying across the screen in an arc while fading out, and then disappearing. I've achieved these 3 effects with an CAAnimationGroup, and it does what I want. The problem is when the animation ends, the view appears back at the original position, full size and full opacity. Can anyone see what I am doing wrong in the code below?
The animation should not revert to it's original position, but just disappear at the end.
UIBezierPath *movePath = [UIBezierPath bezierPath];
CGPoint libraryIconCenter = CGPointMake(610, 40);
CGPoint ctlPoint = CGPointMake(self.imgViewCropped.center.x, 22.0);
movePath moveToPoint:self.imgViewCropped.center];
[movePath addQuadCurveToPoint:libraryIconCenter
controlPoint:ctlPoint];
CAKeyframeAnimation *moveAnim = [CAKeyframeAnimation animationWithKeyPath:#"position"];
moveAnim.path = movePath.CGPath;
moveAnim.removedOnCompletion = NO;
CABasicAnimation *scaleAnim = [CABasicAnimation animationWithKeyPath:#"transform"];
scaleAnim.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];
scaleAnim.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(0.1, 0.1, 1.0)];
scaleAnim.removedOnCompletion = NO;
CABasicAnimation *opacityAnim = [CABasicAnimation animationWithKeyPath:#"alpha"];
opacityAnim.fromValue = [NSNumber numberWithFloat:1.0];
opacityAnim.toValue = [NSNumber numberWithFloat:0.0];
opacityAnim.removedOnCompletion = NO;
CAAnimationGroup *animGroup = [CAAnimationGroup animation];
animGroup.animations = [NSArray arrayWithObjects:moveAnim,scaleAnim,opacityAnim, nil];
animGroup.duration = 0.6;
animGroup.delegate = self;
animGroup.removedOnCompletion = NO;
[self.imgViewCropped.layer addAnimation:animGroup forKey:nil];
I believe you need to set the fillMode property of your animations to kCAFillModeForwards. That should freeze the animations at their end time. Another suggestion (and honestly, this is what I'd usually do) is just se the properties of the layer itself to their final position after you've set up the animation. That way when the animation is removed, the layer will still have the final properties as part of its model.
As an aside, the removedOnCompletion flag of animations contained within a CAAnimationGroup is ignored. You should probably just remove those assignments since they're misleading. Replace them with assignments to fillMode as specified above.