I have a simple animation that im performing in my scroll view delegate method scrollViewDidEndDragging.
It looks like this:
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
NSLog(#"finger was lifted");
[UIView animateWithDuration:1.0
animations:^{
self.homeLabel.frame = self.view.frame;
}];
}
Using this animation after lifting the finger the my homeLabel is coming from top, and i want to add it a bounce animation to the label, so when it comes from top, instead of landing smoothly it will have a nice bounce...how can i DO THAT? thanksss
You can use the usingSpringWithDamping animation function.
[UIView animateWithDuration:1.0 delay:0 usingSpringWithDamping:0.2 initialSpringVelocity:5.0 options:UIViewAnimationOptionCurveLinear animations:^{
self.homeLabel.frame = self.view.frame;
} completion:^(BOOL finished) {
}];
Adjusting the Spring Damping and Initial Spring Velocity can give you the effect you want.
One good solution is to create a custom layer for your view that overrides the addAnimation:forKey: method to include a custom timing function.
This answer goes into the specifics of how to do that.
Another option is to take a look at key frame animation. This question and answer covers that approach very well.
Related
I have UIScrollView subclass. Its content is reusable - about 4 or 5 views are used to display hundreds of elements (while scrolling hidden objects reused and jumps to another position when its needed to see them)
What i need: ability to automatically scroll my scroll view to any position. For example my scroll view displays 4th, 5th and 6th element and when I tap some button it needs to scroll to 30th element. In other words I need standard behaviour of UIScrollView.
This works fine:
[self setContentOffset:CGPointMake(index*elementWidth, 0) animated:YES];
but I need some customisation. For example, change animation duration, add some code to perform on end of animation.
Obvious decision:
[UIView animateWithDuration:3 delay:0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{
[self setContentOffset:CGPointMake(index*elementWidth, 0)];
} completion:^(BOOL finished) {
//some code
}];
but I have some actions connected to scroll event, and so now all of them are in animation block and it causes all subview's frames to animate too (thanks to few reusable elements all of them animates not how i want)
The question is: How can I make custom animation (in fact I need custom duration, actions on end and BeginFromCurrentState option) for content offset WITHOUT animating all the code, connected to scrollViewDidScroll event?
UPD:
Thanks to Andrew's answer(first part) I solved issue with animation inside scrollViewDidScroll:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
[UIView performWithoutAnimation:^{
[self refreshTiles];
}];
}
But scrollViewDidScroll must (for my purposes) executes every frame of animation like it was in case of
[self setContentOffset:CGPointMake(index*elementWidth, 0) animated:YES];
However, now it executes only once at start of animation.
How can I solve this?
Did you try the same approach, but with disabled animation in scrollViewDidScroll ?
On iOS 7, you could try wrapping your code in scrollViewDidScroll in
[UIView performWithoutAnimation:^{
//Your code here
}];
on previous iOS versions, you could try:
[CATransaction begin];
[CATransaction setDisableActions:YES];
//Your code here
[CATransaction commit];
Update:
Unfortunately that's where you hit the tough part of the whole thing. setContentOffset: calls the delegate just once, it's equivalent to setContentOffset:animated:NO, which again calls it just once.
setContentOffset:animated:YES calls the delegate as the animation changes the bounds of the scrollview and you want that, but you don't want the provided animation, so the only way around this that I can come up with is to gradually change the contentOffset of the scrollview, so that the animation system doesn't just jump to the final value, as is the case at the moment.
To do that you can look at keyframe animations, like so for iOS 7:
[UIView animateKeyframesWithDuration:duration delay:delay options:options animations:^{
[UIView addKeyframeWithRelativeStartTime:0.0 relativeDuration:0.5 animations:^{
[self setContentOffset:CGPointMake(floorf(index/2) * elementWidth, 0)];
}];
[UIView addKeyframeWithRelativeStartTime:0.5 relativeDuration:0.5 animations:^{
[self setContentOffset:CGPointMake(index*elementWidth, 0)];
}];
} completion:^(BOOL finished) {
//Completion Block
}];
This will get you two updates and of course you could use some math and a loop to add up a lot more of these with the appropriate timings.
On previous iOS versions, you'll have to drop to CoreAnimation for keyframe animations, but it's basically the same thing with a bit different syntax.
Method 2:
You can try polling the presentationLayer of the scrollview for any changes with a timer that you start at the beginning of the animation, since unfortunately the presentationLayer's properties aren't KVO observable. Or you can use needsDisplayForKey in a subclass of the layer to get notified when the bounds change, but that'll require some work to set up and it does cause redrawing, which might affect performance.
Method 3:
Would be to dissect exactly what happens to the scrollView when animated is YES try and intercept the animation that gets set on the scrollview and change its parameters, but since this would be the most hacky, breakable due to Apple's changes and trickiest method, I won't go into it.
A nice way to do this is with the AnimationEngine library. It's a very small library: six files, with three more if you want damped spring behavior.
Behind the scenes it uses a CADisplayLink to run your animation block once every frame. You get a clean block-based syntax that's easy to use, and a bunch of interpolation and easing functions that save you time.
To animate contentOffset:
startOffset = scrollView.contentOffset;
endOffset = ..
// Constant speed looks good...
const CGFloat kTimelineAnimationSpeed = 300;
CGFloat timelineAnimationDuration = fabs(deltaToDesiredX) / kTimelineAnimationSpeed;
[INTUAnimationEngine animateWithDuration:timelineAnimationDuration
delay:0
easing:INTULinear
animations:^(CGFloat progress) {
self.videoTimelineView.contentOffset =
INTUInterpolateCGPoint(startOffset, endOffset, progress);
}
completion:^(BOOL finished) {
autoscrollEnabled = YES;
}];
Try this:
UIView.animate(withDuration: 0.6, animations: {
self.view.collectionView.contentOffset = newOffset
self.view.layoutIfNeeded()
}, completion: nil)
The standard UIView animateWithDuration: block works great for animations that have require a single animation effect, i.e. resize and/or move.
Is there a way to make the animation progressive, such that the animation starts slow, and gains speed as it progresses?
I could try nested animateWithDuration: blocks, placing subsequent blocks in the completion handler, but that way the animation is a little 'ragged'. I wish to make the animation smooth.
One idea that comes to mind is that I create a recursive function as follows:
- (void) animateToYOrigin:(CGFloat)yOrigin{
if (myView.frame.origin.y < 1){
[UIView animateWithDuration:0.1
animations:^{
CGRect rect = myView.frame;
rect.origin.y = yOrigin;
myView.frame = rect;
} completion:^(BOOL finished) {
[self animateToYOrigin:yOrigin /2];
}];
}
}
I am looking for a refined solution.
You can use
[UIView animateWithDuration:time
delay:delay
options:OPTION_HERE
animations:anims
completion:completion]
method and pass UIViewAnimationOptions where it says OPTION_HERE. You can use basic ease in/out options by default. If you need more options you can check out this git repo. In MTTimingFuncations.h/c you can find multiple options you can pass.
I'm currently creating a loading bar that I would like to pause and reverse if a specific action is taken.
I have the following code below that animates one view in another. How would I go about pausing this animation and applying another animation on the CURRENT frame at that point in time for the animated object. I would like to be able to animate this bar down to the 0 width mark at any given time within the current animation.
-(void)animateProgressBar
{
CGRect endingFrame = self.frame;
[UIView animateKeyframesWithDuration:self.time delay:0.0 options:0 animations:^{
[UIView addKeyframeWithRelativeStartTime:0.0 relativeDuration:1.0 animations:^{
self.loadingBar.frame = endingFrame;
}];
} completion:^(BOOL finished) {
NSLog(#"TADA");
}];
}
If you want to start a new animation from where this one is now, just start the new animation using the the UIViewKeyframeAnimationOptionBeginFromCurrentState option (or if just doing animateWithDuration, use UIViewAnimationOptionBeginFromCurrentState).
You can import QuartzCore framework, add
#import <QuartzCore/QuartzCore.h>
And you can remove existing animation by calling:
[self.loadingBar.layer removeAllAnimations];
After that you can start new animation.
If you want to pause it you have to get reference to the current animation:
CALayer *currentLayer = self.loadingBar.layer.presentationLayer;
And you have to save it:
self.loadingBar.layer.transform = currentLayer.transform;
You can do it in another [UIView animateWith..... method.
I have UIScrollView which can zoom an UIView. One time I want to zoom out to the default state.
Here is my code.
[UIView animateWithDuration:0.3
animations:^{
[scroll zoomToRect:self.view.bounds animated:NO];
} completion:nil];
Wow. It jumps like hell. Seems like it sets zoomScale = 1 and then animating the frame.
I'll add a line.
[UIView animateWithDuration:0.3
delay:0 options:UIViewAnimationOptionBeginFromCurrentState
animations:^{
[scroll zoomToRect:self.view.bounds animated:NO];
} completion:nil];
Works just fine. So how UIViewAnimationOptionBeginFromCurrentState helps in this case? From help I know
Start the animation from the current setting associated with an already in-flight animation.
But there is NO in-flight animations.
I found answer, it looks expedient but work fine.
write animation code in other place use method like 'performSelector:'
then it recognize correct current state
I want something similar in purpose to Flipboard slight flipping animation on app start. Flipboard when launched has this slight flipping of up and down to show users unfamiliar with the interface that it is flippable.
I have a UIScrollView I want to animate a bit to show the user that it's scrollable. So I want to scroll to the right a little bit and back. UIScrollView has a setContentOffset:animated: message without a completion clause. I find that calling it twice results in seemingly no animation. What if I want an animation after animation in succession?
EDIT:
Thanks Levi for the answer.
And for the record, there is UIViewAnimationOptionAutoreverse and UIViewAnimationOptionRepeat that I can use. So this is what I ended up with that works.
CGPoint offset = self.scrollView.contentOffset;
CGPoint newOffset = CGPointMake(offset.x+100, offset.y);
[UIView animateWithDuration:0.5 delay:0 options:UIViewAnimationOptionCurveEaseIn | UIViewAnimationOptionAutoreverse |UIViewAnimationOptionRepeat animations:^{
[UIView setAnimationRepeatCount: 2];
[self.scrollView setContentOffset:newOffset animated: NO];
} completion:^(BOOL finished) {
[self.scrollView setContentOffset:offset animated:NO];
}];
For a scrollView, tableView or collectionView if you do something like this:
[self.collectionView setContentOffset:CGPointMake(self.collectionView.contentOffset.x+260.0,
self.collectionView.contentOffset.y)
animated:YES];
then you'll get back a:
-(void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
when the scroll finishes.
You do NOT get this callback if the user moves the view.
Two options:
1) Use the -(void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView delegate callback
2) Try to put it into an animation block (with ... animated:NO];), which has the completion part.