I am currently trying to make a UIView containing some UILabel animate to a new size. But doing so I am having some trouble understanding what is really happening with my view. I read some other post about it but I am still unclear about what is really going on.
In my button I added something that just double the size of the right constraint :
[superView layoutIfNeeded];
rightConst.constant *= 2;
[UIView animateWithDuration:3
animations:^{
[superView layoutIfNeeded];
} completion:nil];
superView Being the view I wanna animate and rightConst the constraint to the right.
But doing so, the animation starts but it is actually coming from left. I don't understand this part. My goal would be to animate just the right side of the view to show the resize and maybe the bottom part of the view but the top left should be fixed.
Thanks.
As described in this document, if you call [aView layoutSubviews], layout of the subviews of aView is forced but layout of aView itself is NOT forced.
You need to call layoutSubviews of the superview of the view you want to animate. In this case, the superview of the superview of the two labels.
Solution is here
UIView *theView;
// theView is the superview of the superview of the two labels.
theView = superView.superview;
[theView layoutIfNeeded];
rightConst.constant *= 2;
[UIView animateWithDuration:3
animations:^{
[theView layoutIfNeeded];
} completion:nil];
Related
I have a view controller that contains two views. What I need is that after the view controller has been pushed, the view on top (_sidepanelview) moves to the left disappearing of the screen.
Here is what I wrote:
-(void)viewDidAppear:(BOOL)animated{
CGRect newsidepanelviewposition = _sidepanelview.frame;
newsidepanelviewposition.origin.x = -_sidepanelview.frame.size.width;
[UIView animateWithDuration:0.5 delay:1.0 options:UIViewAnimationOptionCurveEaseIn animations:^{
_sidepanelview.frame = newsidepanelviewposition;
} completion:^(BOOL finished) {
NSLog(#"Done!");
}];
}
The problem is that when I run the app, after the view controller been pushed, the view _sidepanelview disappears from the screen and appears again to the center of the screen coming from the right side instead of moving to the left from x=0 to x= -_sidepanelview width disappearing from the screen.
What I'm doing wrong?
Note: I did the app with auto layout unchecked and the animation worked fine, but using it with the auto layout turned on it freaks out!
As your note suggests, Auto Layout is the "culprit".
Your views have constraints that are periodically enforced by the AutoLayout engine. When you alter the frame of a view, the frame changes, but not the view's layout constraints. When the next cycle of layoutSubviews occurs, your views position and size (i.e. frame) will be reset to what the constraints dictate.
If you want to include AutoLayout for that view/viewcontroller, use constraint changes to perform the animation.
The golden rule here is, setFrame is the antithesis of AutoLayout.
Sample code
-(void)viewDidAppear:(BOOL)animated {
_sidePanelLeadingSpace.constant = -_sidepanelview.frame.size.width; // 1
[UIView animateWithDuration:0.5 delay:1.0 options:UIViewAnimationOptionCurveEaseIn animations:^{
[self.view layoutIfNeeded]; // 2
} completion:^(BOOL finished) {
NSLog(#"Done!");
}];
}
Have a reference, _sidePanelLeadingSpace (NSLayoutConstraint), to the leading space constraint of _sidepanelview, for e.g., as an IBOutlet.
Alter the constraint's constant and layout the view by calling layoutIfNeeded in an animation block
I have a view that automatically adjusts it's height based on number of lines in a UILabel within the view. There is another view which height is pinned to be equal to the view with the label.
I would like to animate the height change caused by setting long text to the label, thus changing the number of lines and causing autolayout constraints to recalculate height. This new height will change the height of the second view too. How can I animate autolayout changes that happen as a side effect of property assignment?
I tried this, but it did not work:
[UIView animateWithDuration:0.3 animations:^{
//I want the side effect of this assignment to be animated
self.viewWithLabel.title = #"This long title will change the view height and cause layout change";
}];
See the documentation
Try:
- (void)viewDidAppear:(BOOL)animated {
[self.view layoutIfNeeded];
[UIView animateWithDuration:1.0 animations:^{
self.viewWithLabel.title = #"This long title will change the view height and cause layout change";
[self.view layoutIfNeeded];
}];
}
I think you want yourTextLabel.clipToBounds = YES also.
If you want more advanced effect, see this question.
It's kind the weird I'm facing right now, I know that adding constraints in an AutoLayout IB is simple. But I really couldn't figure-out why my simple constraints are not working when I'm resizing (ZoomIn Animation) a UIView.
The View I'm targeting to zoomIn works fine, but the subviews within it is not being positioned well. It seems that the constraints are not working.
From this setup, where in the Yellow Boxes are UIViews and the Green Boxes are UIImageViews.
When I tapped on a Yellow Box, it should zoomIn, as what is shown on the photo below it.
These are the constraints:
This should be the expected resulting upon zoomIn AnimationBut I got no luck, The yellow box zoomIn but the Green Box is let on its old position and did not changed size.
I put a leading, trailing, topSpace, and bottomSpace from Yellow Box to Green Box already.
My code for resizing the yellow box is:
- (void) resizeViewWithZoomInAnimation: (UIView*)view duration:(float)secs option:(UIViewAnimationOptions) option {
//sets the new width and height of deal's view
float newWidth = view.superview.frame.size.width - 20;
float newHeight = view.superview.frame.size.height - 20;
[UIView animateWithDuration:secs delay:0.0 options:option
animations: ^{
switch ([view tag]) {
case 1:
[view setFrame:CGRectMake(view.frame.origin.x, view.frame.origin.y, newWidth, newHeight)];
break;
case 2:
[view setFrame:CGRectMake(CGRectGetMaxX(view.frame),CGRectGetMinY(view.frame), -newWidth , newHeight)];
break;
case 3:
[view setFrame:CGRectMake(CGRectGetMinX(view.frame),CGRectGetMaxY(view.frame), newWidth , -newHeight)];
break;
case 4:
[view setFrame:CGRectMake(CGRectGetMaxX(view.frame),CGRectGetMaxY(view.frame), -newWidth, -newHeight)];
break;
}
}
completion:nil];
}
This should be the expected resulting upon zoomIn Animation:
When trying to animate with Auto Layout, you should not change view's frames directly. Instead, you should animate changes in constraints.
To access constraints from storyboard you can simply create IBOutlets for them.
[containerView layoutIfNeeded]; // complete pending layout operations (optional)
[UIView animateWithDuration:1.0 animations:^{
// Update constraints
self.viewConstraint1.constant = NEW_VALUE;
self.viewConstraint2.constant = NEW_VALUE;
// Animate the changes
[containerView layoutIfNeeded];
}];
Note that you usually want to call layoutIfNeeded on the super view(or higher) of the view you are trying to animate.
I recommend reading more on Auto Layout in Apple's official guide.
A tweak to the above answer, I used from within a UIViewController
[self.view layoutIfNeeded];
[UIView animateWithDuration:.5
animations:^{
myConstraint.constant = 64;
[self.view layoutIfNeeded];
}
completion:^(BOOL finished) {
// whatever
}];
Changes of note: Apple docs recommend using layoutIfNeeded, and calling this both before and within the animation block. This is so that you can be sure the animation stack is cleared before beginning.
Also, you are to call layoutIfNeeded on the parent view of the constraint you will be animating, not on the view who owns the constraint. Thanks to #nkukushkin for the initial answer.
It's also important to have your constraints set up correctly. The 'fix constraints' tool in IB won't necessary set them up in a way that works correctly for animating. For me I had to go through them and think through how I wanted the dependencies to work, which is of course expected but might not be obvious to the beginner (and results in errors).
When you are using constrains, pre-constrains are generated. When you act on position and size, remove constrains while animating the view or do following:
yourView.translatesAutoresizingMaskIntoConstraints = YES;
I've never worked with autolayout constraints before. I have a small new app I'm working on and noticed that the NIB's views are defaulting to autolayout. So, I figured I'd take the opportunity to work with it and try to figure out where Apple is going with this.
First challenge:
I need to resize an MKMapView and I'd like to animate it to the new position. If I do this the way I'm used to:
[UIView animateWithDuration:1.2f
animations:^{
CGRect theFrame = worldView.frame;
CGRect newFrame = CGRectMake(theFrame.origin.x, theFrame.origin.y, theFrame.size.width, theFrame.size.height - 170);
worldView.frame = newFrame;
}];
...then the MKMapView will 'snap' back to its original height whenever a sibling view gets updated (in my case a UISegmentedControl's title is being updated [myUISegmentedControl setTitle:newTitle forSegmentAtIndex:0]).
So, what I think I want to do is change the constraints of the MKMapView from being equal to the parent view's hight to being relative to the top of the UISegmentedControl that it was covering: V:[MKMapView]-(16)-[UISegmentedControl]
What I want is for the MKMapView height to shorten so that some controls beneath the map view are revealed. To do so I think I need to change the constraint from a fixed full size view to one where the bottom is constrained to the top of a UISegmentedControl...and I'd like it to animate as view shrinks to new size.
How does one go about this?
Edit - this animation is not animating though the bottom of the view does move up 170 instantly:
[UIView animateWithDuration:1.2f
animations:^{
self.nibMapViewConstraint.constant = -170;
}];
and the nibMapViewConstraint is wired up in IB to the bottom Vertical Space constraint.
After updating your constraint:
[UIView animateWithDuration:0.5 animations:^{[self.view layoutIfNeeded];}];
Replace self.view with a reference to the containing view.
This works for me (Both iOS7 and iOS8+). Click on the auto layout constraint you would like to adjust (in interface builder e.g top constraint). Next make this an IBOutlet;
#property (strong, nonatomic) IBOutlet NSLayoutConstraint *topConstraint;
Animate upwards;
self.topConstraint.constant = -100;
[self.viewToAnimate setNeedsUpdateConstraints];
[UIView animateWithDuration:1.5 animations:^{
[self.viewToAnimate layoutIfNeeded];
}];
Animate back to original place
self.topConstraint.constant = 0;
[self.viewToAnimate setNeedsUpdateConstraints];
[UIView animateWithDuration:1.5 animations:^{
[self.viewToAnimate layoutIfNeeded];
}];
There is a very good tutorial from apple itself that explain how to use animation with autolayout.
Follow this link and then find the video named "Auto layout by example"
It gives some interesting stuff about autolayout and the last part is about how to use animation.
I have made this small demo available. It shows how auto-layout constraints can be changed and animated in a very simple example. Simply take a look at the DemoViewController.m.
Most people use autolayout to layout items on their views and modify the layout constrains to create animations.
An easy way to do this without a lot of code is creating the UIView you want to animate in Storyboard and then creating a hidden UIView where you want the UIView to end. You can use the preview in xcode to make sure both UIViews are where you want them to be. After that, hide the ending UIView and swap the layout constraints.
There is a podfile for swapping layout constrains called SBP if you don't want to write it yourself.
Here's a tutorial.
No need to use more IBOutlet reference of the constraint instead of this you can directly access or update already applied constraint either applied by Programmatically or from Interface Builder on any view using the KVConstraintExtensionsMaster library. This library is also managing the Cumulative behavior of NSLayoutConstraint.
To add Height Constraint on containerView
CGFloat height = 200;
[self.containerView applyHeightConstrain:height];
To update Height Constraint of containerView with animation
[self.containerView accessAppliedConstraintByAttribute:NSLayoutAttributeHeight completion:^(NSLayoutConstraint *expectedConstraint){
if (expectedConstraint) {
expectedConstraint.constant = 100;
/* for the animation */
[self.containerView updateModifyConstraintsWithAnimation:NULL];
}
}];
I want to make the width of an UIImageView larger through an animation. I have an UIView with and UIImageView made in the story board. What I want to achieve is so that it looks like the view is scaling from left to right, and keeping its original position. I have tried the following code, but what it does is animating the imageview from the top left corner of its parent view and moving and scaling it until it reaches the position and scale it had from the beginning.
[UIView animateWithDuration:4.0f delay:1.0f options:UIViewAnimationCurveEaseOut animations:^{
CGRect currentFrame = self.imageview1.frame;
currentFrame.size.width = 150;
self.imageview1.frame = currentFrame;
}completion:nil];
Any ideas why this behaviour?
A bit late answer, but I solved the problem. It seems that you cannot change the frame of views in code if autolayout is enabled. Instead you need to animate the constraints of the view, which you can set up in the storyboard and then animate like this:
[self.view layoutIfNeeded];
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
self.bottomViewY.constant = -196;
[self.view layoutIfNeeded];
} completion:nil];
self.bottomViewY is a constraint which is assigned as an IBOulet. You need to call layoutIfNeeded as it will update the constraints.