I've got two UIButtons into a view, which is 232px wide.
The buttons are aligned such as
|[BUTTON1][BUTTON1]|
|-------232px------|
I have a set of constraints for this alignment, but now I want to be able to change the frame of BUTTON1's to full width, depending on a condition, so it'd have to be programmatically. I tried changing the frame, but since it's automatically updated, it won't work. Basically, what I want to achieve is BUTTON1 covering BUTTON2, Is there an easy way to do this?
As you are using autoLayout in your project, so to change the frame of your button, you have to change the constraint of you UIButton.
First make the IBOutlet of your buttons' width constraint and then when you want to change the frame of the button update that constraint like this
button.widthConstraint.constant = //set the constraint;
[UIView animateWithDuration:0.25f
animations:^{
[self.view setNeedsLayout];
}
completion:^(BOOL finished) {
}];
Make the outlet of button and width constraint and then
self.buttonWidthConstraint += 20 // adjust as per requirements
[self.myButton updateConstraints]
You can set the constant of the button you want covered to 0 and animate the change. Then the covering button will fill in the whole space.
Related
I have a UIView called containerView.
I add this as a subview to a controller view's root view. I have programmatically added a few constraints to it (I centered it and made the width a few points from the superview's width).
I have added a few UILabels to the containerView as subviews. The height of the UILabels dictate the height of the containerView.
When the user taps the screen, the containerView is moved up from CGRectOffset() and once the animation is complete, it is moved back to the original position.
CGPoint absolutePoint = self.containterView.frame.origin;
self.containerYConstraint.constant = -absolutePoint;
[UIView
animateWithDuration:0.5
animations:^
{
[viewForUpdate setNeedsUpdateConstraints];
}
completion:^(BOOL finished)
{
self.containerYConstraint.constant = 0;
[viewForUpdate setNeedsUpdateConstraints];
[self.containerView.subviews makeObjectsPerformSelector:#selector(removeFromSuperview)]; // Remove all subviews
}];
I need to remove the UILabels I have put in there as subviews and replace them with different labels. However, the moment I remove one of the UILabel's the entire containerView goes missing (I set the background as red so I can see it). I remove all the subviews in the example but when I try to just remove one the same effect occurs.
Why does this occur? Does this have something to do with auto layout? Also if I want to recenter it after I remove one of the UILabels, how do I re-do the constraints?
Modifying frames when using AutoLayout is a no-no. Once you begin using AutoLayout you're effectively telling the system that you want it to set the frames for you.
Instead of animating the frame directly, create properties pointing to your constraints and animate those constraints.
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.
What I want to achieve is when I tap button, animate frame to be resized so the bottom line position will not change and height will decrease. This part is happening. I also want upper label to move down with frame's upper boundary and lower label to stay put. So I placed constraint in IB for the lower label to have vertical space of 20 pixels and priority of 1000.
- (IBAction)tapTap:(id)sender {
//[self.containerView layoutIfNeeded];
[UIView animateWithDuration:1.5 animations:^{
CGRect rect = CGRectOffset(self.containerView.frame, 0, 30);
rect.size.height -= 30;
self.containerView.frame = rect;
//[self.containerView layoutIfNeeded];
} completion:NULL];
}
Lower label is animating as well and will not stay put. My best guess after trying layoutIfNeeded which didn't work, is that I can't rely on constraints while animating frame. If that is true, what will be solution?
The first rule of AutoLayout: Don't touch the frames (or the center).
It looks like you have already found the answer but the way to do this is to keep a reference to the constraints that you would like to change. For instance, if you want to move the view up and down then store a vertical constraint that sets the vertical position on the view. Now when you animate this constraint the view will animate with it.
self.topConstraint.constant = 50;
// etc...
You can create property references to constraints by CTRL-dragging them just like with buttons, labels, etc...
I have a UIViewController with a UICollectionView and a UIView at the bottom. The way I put it together is displayed in the image below
The yellow square is the UICollectionView and the red is the UIView. This works out just fine. But now I want to resize the UIView because it sometimes contains more info and needs to be bigger. So I tried this:
[self setFrame:CGRectMake(self.frame.origin.x, self.frame.origin.y, self.frame.size.width, self.frame.size.height + 10)];
But this expands the UIView at the bottom and it is not visible. I guess this is because I do not have the correct constraints? I also tried to subtract the origin.y with the same amount and this works only the UICollectionView doesn't get resized with the new height. So how do I tackle this problem?
If you are using autolayout, you should not be setting the frame from your code. Instead you should modify the constant of a constraint that is causing your view to be the incorrect size. You can have an IBOutlet to that constraint and you can change it's constant property. Then call setNeedsLayout on your view controller's view
When setting constraints on your storyboard or in a xib file, animations perform animations on the constraints instead of the sizes and positions.
First create a outlet reference of the constraint which will change (in your case the top space of your UIView to the top layout guide) in the header file of your view controller.
When you want to animate a view, you now have to update its constraints and ask to layout the views.
For example :
[UIView animateWithDuration:0.2
animations:^{
viewYConstraint.constant -= 44;
[self.view layoutIfNeeded];
}
]
//Now don't forget to update constraints
[self.view updateConstraints];
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];
}
}];