I'm new to programming Xcode/objectiveC and this questions seems like it should be painfully obvious but I cannot find an answer; how do i move to a different view controller after an animation completes (without a button or other user interaction). in other words go back to the "home" screen automatically after it finishes. right now the image that is animated just stops moving and stays there after the animation finishes and i'm stuck in that viewController.
i'm guessing the coding should have something to do with the selector but i'm not sure
[UIView setAnimationDidStopSelector:#selector ???];
thanks!
UIView's animateWithDuration has a completion block in which you can put code that is executed when the animation is completed.
[UIView animateWithDuration:duration
animations:^{
animations
}
completion:^(BOOL success) {
[self performSegueWithIdentifier:#"YOUR_SEGUE"];
}];
Related
I am slowly animating a UIImageView from one image to another. Like so:
[UIView transitionWithView:self.backgroundView duration:30 options:UIViewAnimationOptionTransitionCrossDissolve animations:^{
self.backgroundView.image = endImage;
} completion:nil];
Is there some way to terminate the animation partway through, in response to an event?
A certain Tim Oliver tells me this is how you do it:
[self.backgroundView.layer removeAllAnimations];
You can also retrieve the frame the animation ended on using self.layer.presentationLayer.frame, if you need to freeze the view in the partially animated state.
I have a view controller and have a few objects that I have some simply animations hooked up to.
[UIView animateWithDuration:0.25
delay: 10.1
options: UIViewAnimationOptionCurveEaseIn
animations:^{
addNameViewConstraint.constant = 10;
addNameView.alpha = 1.0;
[self.view layoutIfNeeded]; // move
}
completion:nil];
[UIView animateWithDuration:0.25
delay: 0.15
options: UIViewAnimationOptionCurveEaseIn
animations:^{
addEmailViewConstraint.constant = 10;
addEmailView.alpha = 1.0;
[self.view layoutIfNeeded]; // move
}
completion:nil];
When I was using the push segue the animation works fine. But when I switched to using a modal segue the animation stopped working. I increased the delay in the first one to 10.2 seconds thinking that maybe it was animating before I got to see it. I am calling this animation in the viewWillAppear method. Again works if I'm doing a push segue.. but not for modal. Any ideas?
I am calling this animation in the viewWillAppear method
This is a common mistake. viewWillAppear: is too soon to start the animation. The view has not yet appeared so there is nothing to animate. Move the animateWithDuration:... code to viewDidAppear: and all will be well.
This is, however, as you say in your comment, insufficiently satisfying. What you are after is that the modal transition should be happening and your extra animations within the new view should already be happening as the modal view is in the process of appearing. Instead, with viewDidAppear:, the modal view finishes appearing, it settles into place, and then your other animations start, which is not as cool.
One solution might be to move the animations again, this time to viewWillLayoutSubviews. This is trickier because this method gets called a lot. You will need to use a BOOL instance variable as a flag to ensure that your animations run only once. Thus, this should work (I tried it and it seemed fine):
-(void)viewWillLayoutSubviews {
if (!self->didLayout) {
self->didLayout = YES;
[UIView animateWithDuration:0.25 animations:^{
// mess with constraint constants here
[self.subv layoutIfNeeded];
}];
}
}
I am not much into iOS animation. What I am trying to achieve is a simple message view that slide vertical from bottom of screen to a given y, then after few instants the UIView rollback in vertical to go off screen.
[UIView animateWithDuration:0.5f
animations:^{
self.messageView.frame=CGRectMake(x, y -80, width, height);
}
completion:^(BOOL finished){
if (finished) {
[UIView animateWithDuration:0.5f delay:2.0f options:UIViewAnimationOptionCurveLinear
animations:^{
self.messageView.frame=CGRectMake(x, y + 80, width, height);
}
completion:^(BOOL finished){
// do something...
}
];
}
} ];
This is working fine, but I am having a problem using this mechanism in a iOS UITabBar application: when I change tab, the animation stop, I can infact see that "finished" completion is "false". Therefore the second block is not called, and the message view stays on.
Here are the questions:
my first concern is to understand if the code I have written is correct, regarding the nested animations.
I could solve by ignoring 'finished' and execute code anyway, but I don't feel it is a good idea
within the last completion block, I have put some programming logic, basically I am restoring few UIButtons state, and some other little UI change. At this point I don't know if it is a good idea, it seems not, but how can let the UI knows that the message view has disappeared. NSNotification and KVO seems a bad idea when fast responsive UI change are involved.
You can stop all animations for a layer by sending the layer a removeAllAnimations message.
[sel.view removeAllAnimations];
I'm trying to set up an image gallery type view where the image is nearly full screen, and the nav controller, toolbar, buttons (to move between images), and slider (to quickly move between images) all fade out after periods without interaction, and then return on a tap. What I have so far (which I'm sure isn't even close to the right way to do this, I'm something of a beginner) is this:
-(void)fadeOutViews{
[self fadeOutView:rightButton];
[self fadeOutView:leftButton];
[self fadeOutView:mySlider];
mySlider.enabled = NO;
[self fadeOutView:myToolbar];
[self fadeOutView:self.navigationController.navigationBar];
}
-(void)fadeOutView:(UIView *)view{
view.alpha = 1;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDelegate:self];
[UIView setAnimationDuration:2];
view.alpha = 0;
[UIView commitAnimations];
}
-(void)stopFadeOut{
[rightButton.layer removeAllAnimations];
[leftButton.layer removeAllAnimations];
[mySlider.layer removeAllAnimations];
[myToolbar.layer removeAllAnimations];
[self.navigationController.navigationBar.layer removeAllAnimations];
}
-(void)resetToInitialConfigurationWithDelay:(int)delay{
if (buttonWasPressed){
delay = 4;
buttonWasPressed = NO;
}
rightButton.alpha = 1;
leftButton.alpha = 1;
mySlider.alpha = 1;
myToolbar.alpha = 1;
self.navigationController.navigationBar.alpha = 1;
mySlider.enabled = YES;
[self stopFadeOut];
[self performSelector:#selector(fadeOutViews) withObject:nil afterDelay:delay];
}
So, the theory is, you reset to the initial state (the delay is because images fade in and out when using the buttons to advance, so there needs to be more time in before fading after a button press, or else the fading started immediately after the new image loaded. This resets everything to how it started out, and begins the process of fading again. And stopFadeOut removes all the animations if something occurs that should stop the fading process. So, for example, if a tap occurs:
- (IBAction)tapOccurs:(id)sender {
[self stopFadeOut];
[self resetToInitialConfigurationWithDelay:2];
}
Any previous animations are stopped, and then the process is restarted. Or at least that's the theory. In practice, if, say, there are several taps in quick succession, the faded views will start to fade briefly, and the reset, over and over again, so that it looks like they are flashing, until they finally fade out completely. I thought that perhaps the issue was the the animations were delayed, but the removeAllAnimation calls were not, so I replaced
[self stopFadeOut];
with
[self performSelector:#selector(stopFadeOut) withObject:nil afterDelay:2];
but the results were the same. The behavior is EXACTLY the same if stopFadeOut is never called, so the only conclusion I can draw is that for whatever reason, the removeAllAnimations calls aren't working. Any ideas?
What is happening
It sounds to me like the reset method is called multiple times before the previous run finished. You could easily verify this by adding log-statements to both the tap and reset method and count the number of logs for each method and watch what happens when you tap multiple times in a row.
I've tried to illustrate the problem with drawing below.
T = tapOccurs:
O = fadeOutViews:
--- = wait between T & O
Normal single tap
T-----O T-----O
---------------------> time
Multiple taps in a row
T-----O
T-----O
T-----O
---------------------> time
What it sound like you are trying to do
T-
T---
T-----O
---------------------> time
Every time fadeOutViews: (called O in the illustration) gets called the view will fade out. Looking at your fadeOutView: implementation this means that the opacity will jump to 1 and then fade slowly to 0, thus it looks like they are flashing an equal number of times to the number of taps until finally starting over.
How you can prevent this
You could do a number of things to stop this from happening. One thing would be to cancel all the scheduled reset methods by calling something like cancelPerformSelectorsWithTarget: or cancelPreviousPerformRequestsWithTarget:selector:object:.
I'm looking for a way to implement consecutive animations using nested animation blocks.
Somewhat complicated by happening inside a UIScrollView, the size of three UIImageViews (there are many images, and as I scroll through them I constantly swapping out the images in the UIImageViews).
When a scroll is finished, I want to switch out the image in the (visible) middle UIImageView, three times, then back to the original view. I'm trying it thus:
- (void) doAnimation {
// get the animation frames, along with the current image
NSString *swap1 = #"first.png";
NSString *swap2 = #"second.png";
UIImage *original = currentPage.image;
UIViewAnimationOptions myOptions = UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionAllowUserInteraction;
[UIView animateWithDuration:2.0 delay:2.0 options:myOptions
animations:^{ [currentPage setImage:[UIImage imageNamed:swap1]]; }
completion:^(BOOL finished) {
[UIView animateWithDuration:2.0 delay:2.0 options:myOptions
animations:^{ [currentPage setImage:[UIImage imageNamed:swap2]]; }
completion:^(BOOL finished) {
[UIView animateWithDuration:2.0 delay:2.0 options:myOptions
animations:^{ [currentPage setImage:[UIImage imageNamed:swap1]]; }
completion:^(BOOL finished) {
[currentPage setImage:original]; }]; }]; }];
}
When I run this, there is no duration, no delay, it all happens at once, almost too fast for the eye to see. Could this be because "currentPage" is a UIImageView? (Similar to this question?)
There's no delay because UIImageView.image isn't an animateable property. As such, the UIView animation machinery will have no animations to set up and will just call your completion block immediately.
What sort of animation did you expect? You can attach a CATransition object to the underlying layer to get a simple cross-fade, Just use [imageView.layer addAnimation:[CATransition animation] forKey:nil] to get the crossfade with the default values (you can customize the timing by modifying properties of the CATransition before attaching it to the layer). To achieve the subsequent animations, you can either use the delegate property of CAAnimation (CATransition's superclass) to learn when it's done and fire your second one, or you could just use -performSelector:withObject:afterDelay: to start your next animation step after a user-defined delay. The delegate method is going to be more accurate with regards to timing, but the performSelector method is a bit easier to write. Sadly, CAAnimation doesn't support a completion block.
Another approach for you to transition from one image view to another is by using the block animation function transitionFromView:toView:duration:options:completion as discussed in "Creating Animated Transitions Between Views". You would do this instead of animateWithDuration to change images.