I am making a score marker for a game. As the score grows I want the marker to grow so it can accommodate the extra digits that are being added. I want the resizing to be smooth and also animate the new score that is displayed. At first I was using a UILabel but later found out I can't animate the background and the text independently (because they are in the same layer).
I decided to subclass UIView and add a CATextLayer as a sub layer so I can now animate the background (the UIView layer) and the text (the CATextLayer sub layer) independently.
It works great except for one thing, I placed the marker at the center bottom of of the screen like this:
the problem is that I get an error saying I should add constraints for x and y position or width and height. Since I want the view to be able to grow I can't add size constraints, and since it's is relative I can't add x or y constraints. Using an inequality constraint is useless as the error still occurs.
I know this isn't a problem using ILabel, UIButton or some other subclass of UIView. I guess I could subclass UILabel instead and just leave the text empty to achieve the same effect plus I won't have to worry about those constraints, but that feels somewhat wrong. Besides UILabel already is a subclass of UIView so I guess there probably is an option to avoid having to set size constraints.
Is there something I can do to still subclass UIView or should I just subclass UILabel or something like that and get it for free.
Try CONTENT HUGGING PRIORITY. or CONTENT COMPRESSION RESISTANCE PRIORITY. Here is a tutorial to understand about them clearly, if you are not familiar with them.
Hugging priority Vs Compression resistence
There is another option to try. If getting auto layout errors is the only problem you are facing, except everything is fine, you can use Place holder constraints.
Related
I’ve taken a lot of time to read other questions before asking this one, and haven’t managed to solve the issue yet – hopefully someone can help.
I have a custom alert view, a UIView subclass. I’m trying to get it into a state where its width is fixed, and its height grows dynamically based on the height of its two labels (title and message), and a dynamic number of action buttons it can be set up with.
I’ve used AutoLayout to set up the controls, which is working fine, but for now I’m still manually setting the frame of the view itself in its initialiser.
What I need to do is have the view’s height be calculated by the height of my two labels, and n buttons, plus the spacing between them.
I’ve tried providing an intrinsicContentSize for my view, but that method is never called, and it doesn’t even ask for it, so I’m stumped as to how to proceed.
To summarise: I probably need iOS9’s UIStackView, but I don’t have that luxury, so I need to bake something similar into iOS 7 / 8. I’ve looked at OAStackView but I’d rather not use an external dependency.
Just a quick thought: Have you tried to create the view in Interface Builder? Give it a fixed width with Priority: 1000. Add no Height constraint but center the view vertically in its superview.
Then set the View's vertical content hugging priority and vertical content compression resistance priority to 1000.
This should cause the view to calculate its own height based on its subviews. You only need to make sure, that the subviews are bound to the superview in a way that defines the height without any ambiguity.
I'm trying to adjust the size of a button to (it's intrinsic size + a little bit more) in order to draw a custom background. However, every time I access self.titleLabel within the button, the size and position resnaps to that of the storyboard. I don't have to do anything with the label to reproduce this, just retrieve it from the button.
I've put logging code all over my button and view controller in order to find where this is happening. It's not coming from a relaying-out of subviews or any other notification I see to get within the view controller. The line before accessing titleLabel, the position and size are correct. The line after, it has snapped back to the storyboard position. Commenting out the access prevents the size/position snapping. Can someone tell me where or why this is happening?
I have no constraints set (that I can tell), but am I fighting against auto-layout here? Should I be doing this a different way like composing controls or something?
Something similar (or the same?) has been asked before at UIButton modifying titlelabel seems to change its frame and UIButton titleLabel resizes on press?, but both were left unanswered or explained away with just "maybe a bug."
If the project has auto-layout enabled, then YES, you're fighting auto-layout. You have two choices, either subclass UIButton so that you can override the intrinsic size calculation, or modify the constraints so that the intrinsic size is not used in any constraint. If you do the latter, then you probably want to create an IBOutlet to the constraint for the width, so that you can adjust the constant property as needed.
This isn't a bug, it's a consequence of auto layout. When using auto layout, you shouldn't set any frames. Instead, you should change the size or position by modifying the constraints. What's happening, is that whenever the view needs to be redrawn, the frame reverts to the frame that's defined by the constraints.
I cant for the love of god the the hang of this resizing superview.
I have a UIView *superview with 4 UILabels. 2 function as header for the 2 others.
The content in all 4 are dynamic coming from database.
SizeToFit vs SizeThatFits:(CGSize) vs UIView systemLayoutSizeFittingSize:, passing either UILayoutFittingCompressedSize or UILayoutFittingExpandedSize.
I use autolayout programatically and have set the superview height to be equal or greater to a dummy number.
where and how do I use these SizeToFit vs sizeThatFits:(CGSize) vs UIView systemLayoutSizeFittingSize:, passing either UILayoutFittingCompressedSize or UILayoutFittingExpandedSize. I have read a lot of tips here on stack but ended up with nothing.
DO I need to recalculate the constraints for the superview somewhere specific. Maby setting the height to be ´#property` in its controller class and remove and readd it?
Atm I have tried to put everything everywhere and then some. Still I get the same size end result with the dummy height and text floating outside. Even after setting clipsToBound on subview.
I am scratching my hair of.. help
If you're using Auto Layout, here's what you need to do:
Make sure you aren't adding fixed width and/or height constraints to any of your subviews (depending on which dimension(s) you want to dynamically size). The idea is to let the intrinsic content size of each subview determine the subview's height. UILabels come with 4 automatic implicit constraints which will (with less than Required priority) attempt to keep the label's frame at the exact size required to fit all the text inside.
Make sure that the edges of each label are connected rigidly (with Required priority constraints) to the edges of each other and their superview. You want to make sure that if you imagine one of the labels growing in size, this would force the other labels to make room for it and most importantly force the superview to expand as well.
Only add constraints to the superview to set its position, not size (at least, not for the dimension(s) you want it to size dynamically). Remember that if you set the internal constraints up correctly, its size will be determined by the sizes of all the subviews, since its edges are connected to theirs in some fashion.
That's it. You don't need to call sizeToFit or systemLayoutSizeFittingSize: to get this to work, just load your views and set the text and that should be it. The system layout engine will do the calculations for you to solve your constraints. (If anything, you might need to call setNeedsLayout on the superview...but this shouldn't be required.)
Use container views
In the following example I have a 30x30 image, and the UILabel is smaller than the containing view with the placeholder text. I needed the containing view to be at least as big as the image, but it needed to grow to contain multi-line text.
In visual format the inner container looks like this:
H:|-(15.0)-[image(30.0)]-(15.0)-[label]-(15.0)-|
V:|[image(30.0)]|
V:|[label(>=30.0)]|
Then, set the containing view to match the height of the label. Now the containing view will ride the size of the label.
As #smileyborg pointed out in his answer, connecting the content rigidly to the superview informs the layout engine that the simple container view should cause it to grow.
Yellow alignment rectangles
If you want the yellow alignment rectangles add -UIViewShowAlignmentRects YES in your scheme's list of run arguments.
This almost follows #smileyborg answer and comes with a concrete example.
Won't describe all constraints, but those related to the calculation of the height of UI objects.
[Label] Labels must not have a fixed height constraint, in this case, AutoLayout won't resize labels to fit the text, so setting edge constraints is the key. (green arrows)
[Subview] Steps 1 and 3 are very easy to follow, but this step can be misunderstood. As in the case with labels, subviews must not have height constraint set. All subviews must have top constraint set, ignoring bottom constraint, which can make you think will trigger unsatisfied constraint exception at runtime, but it won't if you set bottom constraint for the last subview. Missing to do so will blow the layout. (red arrows)
[Superview] Set all constraints the way you need, but pay big attention to the
height constraint. Assign it a random value, but make it optional, AutoLayout will set the height exactly to fit the subviews. (blue arrows)
This works perfectly, there is no need to call any additional system-layout update methods.
This was made dramatically easier with the introduction of Stack Views in iOS 9. Use a stack view inside your view to contain all your content that resizes, and then simply call
view.setNeedsUpdateConstraints()
view.updateConstraintsIfNeeded()
view.setNeedsLayout()
view.layoutIfNeeded()
after changing your content. Then you can get your new size by calling
view.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize)
if you ever need to calculate the exact size required for a view.
I really hate to ask here because I usually try to figure things out on my own. But on this one I've stuck for days and can't find a solution anywhere online.
I have a ScrollView containing multiple subviews. I've got an image view and two labels at the top with fixed heights. Then there is a UITextView and another ImageView (see pictures).
I add the text to the text view programmatically so it should have a dynamic height and the ImageView should move to the bottom so you can scroll. I don't want the TextView to be scrollable in itself but I want all the subviews to move as well.
I know I should be able to solve this issue using constraints. But I feel like I've tried everything and nothing worked yet. It worked when I disabled auto layout and moved the views manually. I'm wondering if there is a better way though.
As you can see I pinned the TextView to the ImageView above with a 1,000 priority and to the ImageView below with a 1,000 priority. The height constraint can not be deleted so I set it to the lowest possible priority. The ImageView on the bottom is pinned to the bottom of the superview with an absolute height. Its height constraint also has low priority. (I can post an image of the ImageView's constraints, if it helps)
I also tried adapting the frame programmatically but this is not working well in combination with auto layout. (If it helps I can of course post the code)
What am I doing wrong? Shall I just disable auto layout and do it manually? This seems unclean to me. Is it even possible to do?
I really appreciate your help :)
Greets,
Jan
Make sure the Scrolling Enabled attribute on the UITextView is unchecked in Interface Builder. I believe that the Auto Layout system takes that into account when it calculates the intrinsic content size.
If somebody is struggling with a similar problem: This is what I ended up doing:
Remove all subviews from the ScrollView in IB
Programmatically add a single UIView to the ScrollView.
Add all the views to the UIView as subviews (move them using setFrame)
Set the Frame of the UIView appropriately to the subviews
Set the ScrollView's contentSize to the size of the UIView.
A little more work but it finally works. This follows Apple's mixed approach guidelines that can be seen here (look for UIScrollView): http://developer.apple.com/library/ios/#releasenotes/General/RN-iOSSDK-6_0/index.html
The problem is the height setting. You somehow have to try to delete it. If you have added other constraints that are "sufficient", it should become deletable.
At the moment you have one user constraint for the height that is "Greater or equal" and an "Equals" constraint as well. Clearly, those are not working well together.
Maybe there is a conceptual error as well. The lower image view should not be fixed in position, so the distance to the lower image view will not be a "sufficient" constraint to let you delete the fixed height.
I think it should work if
the lower image view has a fixed height and
a fixed distance to the text view above, and
the text view has a minimum height as well as
a fixed distance to the image view above
(which should be fixed in relation to the superview).
I have one UIView and inside that, N UILabels which are laid out relative to each other.
The containing UIView has a background color, I want to extend the UIView to be high enough to cover all labels inside it, so the background color is behind them all.
(I'm embedding them in a UIView so I can have the labels inset from the view edges.)
Is there away to make the UIView's height expand to fill its content? I can't figure it from the constraint options, it seems like its all relative to superviews.
Normally I'd just work out the frame sizes programatically in viewDidAppear but those are getting reset by the constraints system, AFAIK.
I think I actually worked it out though.
I had the labels height set manually from when I drag-dropped and resized it. Deleting the height constraint on the UILabel made it size to fit content, which causes its superview to resize too. At least I think that's the case, I'm new to constraints.
Will leave the question up since it will probably bite someone else too.