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];
Related
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'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"];
}];
Same code as in a previous question, but a different issue.
I've created a custom animation to add a view controller to a UINavigationController. This code scales a view to 80% the original size, then flips it, then scales it back up to its original size:
[UIView animateWithDuration:scaleDuration delay:0 options:UIViewAnimationOptionCurveEaseIn animations:^{
// Scale the controllers' views down.
self.view.transform = CGAffineTransformScale(self.view.transform, 0.8, 0.8);
} completion:^(BOOL finished) {
// Transition to the new view and push on the new view controller.
[UIView transitionWithView:self.view duration:1 options:UIViewAnimationOptionCurveLinear | UIViewAnimationOptionTransitionFlipFromLeft animations:^{
[self pushViewController:viewController animated:NO];
} completion:^(BOOL finished) {
[UIView animateWithDuration:scaleDuration delay:0 options:UIViewAnimationOptionCurveLinear animations:
^{
// Scale back to the original size.
self.view.transform = CGAffineTransformScale(self.view.transform, 1.25, 1.25);
} completion:nil];
}];
}];
The issue is that, when the animation completes, the new view is displayed very nicely, except that it is drawn under the task bar. That is, it draws in at screen origin 0,0, rather than 0,20. The "Status Bar" option is set in IB (to "Black"), and, naturally, this does not happen if I use a standard UINavigationController push animation, only my custom one. If I rotate the device after the animation, the redraw on rotation moves it to the proper place. But how do I get it to do that in the first place?
As an added wrinkle, it does not draw under the task bar if I move the pushViewController:animated: call a line down to the completion: block (though then the view appears to flip to itself and then suddenly show the new view, of course).
I found the only work around so far is hide the navigationbar and then show it.
after you set your transform, add following 2 lines:
[self setNavigationBarHidden:YES];
[self setNavigationBarHidden:NO];
It's ugly but works, I am also looking for a better solution.
note: layoutsubview, setNeedsLayout won't work.
I have a UIScrollView here where I'm adding displaying a label in the middle of the screen when the user has scrolled to a page, the problem is that while the animation is going the user can't scroll to the next page (all user interaction seem to be disabled) until the animation is over.
Here's my code for displaying the label.
if(!scrollView.dragging)
[UIView animateWithDuration:0.3
delay:0.3
options:UIViewAnimationOptionCurveEaseOut
animations:^(void){
[vesselNameLabel setFrame:frame];
}
completion:^(BOOL finished){}];
So how would I get out of this canceling user interaction on the scrollview?
Okay, so I figured this out.
Turns out UIView's block animation by default blocks user interaction, and to get around it you need to pass UIViewAnimationOptionAllowUserInteraction as one of the options. Hopefully someone else will have some use of this information as well.
we noted a strange behaviour if alpha becomes 0 ... touches are ignored.
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.