I have:
application, that should work in landscape and portrait mode.
view with full-size scroll view on top.
some view inside scroll view with fixed width and height. (with added H and W constraints)
set to view inside scroll view as horizontal centered in container. (added according constraint)
I have warning in interface builder "Has ambiguous scrollable content width".
The only way to fix this problem, that I know - is set trailing and leading constraints.
But for different iPhones (5.5", 4.7", 4") I need to set different trailing and leading constraints.
How can I eliminate this warning and still have centered horizontally view with fixed W and H for all iPhone sizes?
I create Github repo to illustrate this problem: ScrollViewAmbigous
This is not duplicate of UIScrollView Scrollable Content Size Ambiguity
, but it similar (and not answered although), but this question especially related to different sizes of iPhones.
In the morning with a fresh cup of coffee I figured out workaround for this issue!
So, here is the initial state for simplest case:
scrollView with 0 constraints to all edges
Button centered Horizontal and Vertical with fixed Width and Height
And, of course Has ambiguous scrollable content width and Has ambiguous scrollable content height annoying warnings.
All, that we have to do is:
Add 2 additional constraints, for example "0" for trailing and/or bottom space for our view (in my case - UIButton)
Important: you have to add trailing and/or bottom constraints. Not "leading and top" - it's not works!
You can check it in my example project, that demonstrating how to fix this issue: ScrollViewAmbigous
P.S.
I don't know why it works and how Xcode detect which constraint is more prioritised (because I'm not set priority for these constraints explicity), but I'll be thankful if someone explain, why it works in comments below.
Problem :
The warning is telling us that the the content size of the
scrollview depends on its subviews.
while your subview don't have any strict rule of position and size (no fixed constraints) it will confuse nib generated scrollview
content size.
Solution :
Make only one subview as a 'contentView' for scrollview.
Add strict (fixed) constraints to that 'contentView'.
Best practice : equal width and height to its scroll view.
Add all other subviews and constraints to your 'contentView'.
There seems to be a lot of confusion on this issue. My take is that a UIScrollView must have TWO trailing space constraints, an 'inner' one connecting it to one of it's subviews (so it can know its content width), and another 'outer' one connecting it to a sibling or superview so it knows its frame width.
Same principle applies for height, i.e. two bottom space constraints.
Related
Simple goal, but it demonstrates situations where Auto Layout gives me a headache. I want to have a stack view with a width of 256pt and a dynamic height based on layout (I shouldn't have to manually specify the height).
Inside it should be an image view sized 64pt x 64pt, which should also be centered horizontally as well as constrained 8pt from the superview's top. Note that the image view isn't the only child, hence why the stack view's height must be sized dynamically.
Auto Layout now tells me there's a conflict between the 256pt width constraint of the stack view and the 64pt width constraint of the image, as well as some mysterious "leading = Image.leading" and "trailing = Image.trailing" conflict which I can't even delete nor find.
Am I missing out something here regarding Auto Layout? I expect all logic to be contained in the interface builder, so no code should be required.
Running Xcode 9.1
Layout image
There is nothing to confuse. iOS clearly telling you the issue.
StackViews take size based on the size of child components (this is called implicit size) unless its been overriden manually as in your case which is 256pt.
Because stackView is just a container for multiple childViews stacked either horizontally or vertically, now because you have added only one imageView to it, it adds the leading and trailing constraint to it which makes absolute sense because you added a single view to the stack of view's , now what should stackView do? stretch childView (in your case imageView) to its own size.
But then you did not allow it because you added width constraint to imageView now when it tries to increase the imageView's width imageView's constraint wont allow it.
Hence it is complaining that there are too many conflicting constraints. Thats all :)
some mysterious "leading = Image.leading" and "trailing =
Image.trailing" conflict which I can't even delete nor find.
You cant delete them because, imageView is the only view inside stackView. Because there is only one child view to stack, stackView will start from left side (leading) to right side (trailing). Because now stackView has its own width it tries to change the width of imageView to reflect the same! But images width constraint prevents it from happening.
What are you trying to achieve with imageView added to stackView. If there is only one view in stackView, adding stackView does not make any sense. Reconsider what you are doing.
Finally, when you have only one childView in stack view, adding horizontal center does not make any sense (no matter vertical/horizontal stackView).
I am making a note taking app in xcode8 for iOS 10.2. The note is consist of a textfield, textview and imageview. I am adding textview and imageview in separate scrollviews (to provide the facility of zooming and adjusting image). Then I have added both scroll views in a stackview to ensure that imageview and textview stands side by side in a landscape mode. To do that, I have added variation to axis property of stackview( width=any, height= compact and Gamut=any, and set that to the horizontal, as shown in right corner of screenshot to see view hierarchy without any constraints).
I have tried many constraints but, every time it fails to adopt. Let's take an example, I am adjusting size of the scrollviews on the size of content(by setting top,bottom,leading and trailing constraint), the stack view is adjusted to the main view. Now, the only thing that needs to be adjusted is text view and imageview with respect of stack view. But, here is the tricky part If I include a fixed trailing constraint of text view to the stack view; it will work in portrait mode.As soon I turn into landscape mode that constraint will not work(the trailing constraint which have 0 distance from stackview) because the edge will be side to the imageview not to the stackview(because I am putting image and text side by side as explained above) which will make textview larger than required, same goes for imageview's leading constraint to the stack view and vertical distance constraint betweem image view and textview.I think the root of the problem is I have made a variation to the axis of a stack view (in order to get text and image side by side in landscape mode) but, that was necessary part.Can anyone have solution for this? Do you think there can be other problem? Should I choose Intrinsic Size of scrollviews to placeholder option or let it be system default?
Thank you.
So I hope I understand the question and I will try to walk you through what I understand you hope to accomplish. I preface this by saying I just started using UIStackView because of backwards compatibility.
Note. To get the magic of ScrollView with AutoLayout I almost always embed them in another UIView. There are reasons to not but in this case you will see how valuable this is to AutoLayout.
Step 1) Drag your UIStackView and add Top,Bottom,Leading, and Trailing. Now add 2 UIViews and set the UIStackView to Fill Equally. It will now look like the image(Background colors to check your work).
Step 2) Now add a UIScrollView to each of these UIViews. Add Leading,Trailing,Top,and Bottom on each of these.
Step 3) Add a UITextView and UIImageView to the ScrollViews respectively. Now Autolayout is mad at us :( but we will fix that.
Step 4) Drag from the UIImageView to the View that is holding the UIScrollView(First Set of Views we added). See image
-Choose the option to add Equal Widths. See Image
Repeat the same step but add Equal Heights. Now add Top, Bottom, Leading, and Trailing to the ScrollView.
Step 5) Repeat exact Step 4 with UITextView
Your final view hierarchy should look like this.
Now you can rotate your UIStackView and do what you want I think.
And Horizontal
Side by Side Preview
I did add a <= 0.1 equal heights multiplier on the textfield at the top but I don't know if that was necessary.
Enjoy.
I am creating a UIScrollView from xib, in which 3 view are there 2 UIViews and in middle an UIImageView. when I am setting constraints Xcode asked to set Y position constrains. But the problem is Y position constraint is blocking Scrollview to scroll down and automatically adjusting the views which looks ugly in landscape mode.
when I am delete that constraint it ask to fix height of subview. I searched a lot but I am new in autolayout so not understanding many of solutions. any help would be great.
You have to set all the height constraints in the content view.
But you also want the height of the Content to be proportional to the screen size.
To do this assign the height constraint of the imageview [equal|proportional|a-computation-of] to the view containing the UISCrollView.
It seems weird to skip levels of herarchy when assigning constraints between two views whose are not direct ancestor/sibling of each other but within a scrollview (at least) it is perfectly acceptable.
You are basically telling the scrollview that it's content has a known size and at same time setting this content to adapt dinamically to the screen size (if the constraints of the root uiview are set correctly)
UIView1
|---UIScrollView
|---UIView2
|---UIImageView [heightConstr.constant=UIView1.height-UIView2.height-UIView3.height-margins]
|---UIView3
This is the basic idea, to be done programmatically, then you can explore other solutions.
Unfortunately the constraint system in ios pretty much sucks when it's up to more complex equations involving more views for a single constraint.
UIScrollViewcan be tricky when adding constraints. You should always add a subView that will behave as the content view for your UIScrollView and all your subsequent views will go inside this content view.
UIView1
|---UIScrollView
|---UIContentView
|---UIView2
|---UIImageView
Set your UIScrollViewconstraints as you would normally but set your content view to have leading, trailing, top and bottom to the UIScrollView but also add two more constraints which will be equal width and equal height to the viewController.view but will have a low priority (So that whichever direction your content will increase in, that constraint will break and automatically increase the content size of the scroll view by taking in the inferred height of the content view). Now go on and add constraints on all your subview as you normally would. Which i'm assuming would be:
Your topmost view will have top and leading and trailing to its superView and also a fixed height.
Your bottom view will have leading, trailing and bottom to its superView and also a fixed height.
Your UIImageViewwill have a leading, trailing and top to top most view and bottom to the bottom view.
Edit:
Here is the screenshot just in case (To show the view hierarchy with the content view's constraints in the inspector)
When I first learned Autolayout, things where not too bad as you only had 1 width to cope with. I am struggling to get a Scrollview to grow depending on device (width) and its content equally. The scrollview has paging on so a StackView is not possible I believe.
The current issue is the first view grows to the right width (I believe its down to the centerX), however the overall content size of the scrollview is not large enough (iPhone 6) and the secondView is only 320 wide.
I could do this in code but I am sure you don't need to.
I have tried quite a few options like saying greater than on the width
As i understood your question, you want autoresize for views inside scrollview. So, instead of creating width constraint, you should add 'equal width constraint' to your target view:
second step
if scrollview tells you, that it has ambiguous scrollable content, add bottom constraint for it.
Basically, if you need autolayout inside scroll view, you should provide contentView and setup it with trailing, leading, top, bottom contstaint to scroll view:
This trick allow you to add another object inside scrollview and use autolayout easily.
Hope this helps
I've got a scroll view contained directly inside the content view of a view controller, at full size in both dimensions. The top, bottom, leading and trailing space constraints from the scroll view to its superview (horizontal) and the layout guides (vertical) are all set to 0. The VC is eventually meant to be nested as a child view controller in one or two places. I'm using a Storyboard.
I've placed a number of elements inside the scroll view and constrained them to it, but I'm seeing various kinds of strange behavior. Below is a screenshot with all the subviews of the scroll view selected to display their constraints. The scroll view's four constraints to the top level view are not visible in it. The view controller has been set to Freeform size, with its top level view (and, accordingly, the scroll view's content view) 616 pts high, guaranteeing that scrolling will be necessary at runtime.
Before analyzing the screenshot, here's a list of things that I'm trying to achieve.
The vertical spacing between elements is set by the designer and fixed. (BTW, none of the vertical constraints, text styles etc. in this wireframe are final yet; the whole image is for illustrative purposes only.)
All the labels (except the topmost one) should start at their intrinsic size, expand up to the width of the scroll view (minus the standard HIG horizontal space of 20 pts on both sides).
Buttons are unlikely to be much bigger than this, but in case of localization surprises, we want them to behave just like the labels. (There's an extra vertical ≥ constraint on "Another Button"; it's irrelevant to this question.)
The web view has a fixed height, and its width should be determined by the width of the scroll view; standard 20 pt horizontal space on both sides.
The text views have a minimum height (67 pts here), but they should expand vertically if the contained text is too big to fit. None of them are editable or scrollable. Like the web view, they're horizontally spaced the standard 20 pts apart from the leading and trailing edges.
As you can see, none of the elements have explicit width constraints. The whole thing relies on the leading and trailing space constraints between the elements and the scroll view. The layout, in my mind, would somewhat gracefully work on hypothetical wider-than-320 pt iPhones of the future without changes to the constraints. It would also work after rotating to landscape orientation (it might look a bit silly, but it would work).
I'll go through the points step by step, referring to the screenshot where necessary.
1: This works, nothing out of the ordinary here.
2: The leading constraints of the labels are all simple Equal 20 pt standard spaces. The trailing constraints are Greater Than or Equal 20 pt standard, ostensibly to allow them to grow to be scrollView.frame.size.width-40 wide, but no wider.
3: Same as 2.
4 and 5: Here's where it gets interesting. The web view and the text views are all listed as Misplaced Views, with IB saying their frames will be different at runtime. The orange dashed borders denoting the correct frames only reach horizontally as far as the longest element with a Greater Than Or Equal trailing constraint; here, it's "A Button With A Long Title", whose right edge is where the dashed border edges end.
Constructing this set of views and their constraints, I expected to have some trouble. I knew it would be tricky to have UITextViews that grow vertically taller than the ≥ 67 height defined here, perhaps only possible through code. Getting the labels and buttons to work as specified above through IB alone seemed a bit iffy, too.
What I didn't expect was the web and text views' reported correct frame being only as wide as the widest label or button. It seems that with this setup, the scroll view won't actually be 320 pts wide, but rather only as wide as necessary to fit the longest element and its spacing, and the web and text views are expected to comply. Given that the scroll view is firmly constrained on all sides to the top level view, which is set to be 320 pts wide, I have no idea why this is. SOMETHING must obviously define the initial width of the scroll view, but why aren't the constraints I've made from the scroll view to the top level view doing that?
Given the specifications above for this set of views, what do I need to change to make it happen?
This case demonstrates the fact that I truly do not properly understand Auto Layout yet, and I hope that the answers will enlighten me about many of its crucial aspects.
With respect to Xcode's warnings about misplaced views, select the view controller in storyboard, tap the "Resolve Auto Layout Issues" button in the lower-right-hand corner of the canvas (it looks like a Tie Fighter from Star Wars), then select "Update All Frames in View Controller". This forces all of your views to reflect their constraints.
Using Auto Layout with UIScrollView is a different animal; so much so that Apple felt it necessary to release a Technical Note on the issue: https://developer.apple.com/library/ios/technotes/tn2154/_index.html
When you connect all those constraints between subviews and the inside walls of a scroll view, the result is probably not what you expect. When you pin a subview to the sides of a scroll view, you are not in fact determining the subview's position relative to the scroll view. Instead, you are determining the scroll view's contentSize. This is weird.
You are using Apple's so-called pure Auto Layout approach from the Technical Note. With this approach, the subviews' constraints must dictate the scroll view's contentSize.
Let's take just one of your subviews and ignore all the rest, say one of the text views. And let's only think about that text view along the horizontal axis. If you wanted the text view to be constrained by the width of the scroll view without any horizontal scrolling, you would need to install a fixed-width constraint on the text view that was exactly the width of the scroll view's bounds minus the spacers. After doing this, the content size width would be the sum of the left spacer, the width of the text view, and the right spacer.
Unfortunately, you cannot install a constraint that establishes a relationship between the width of the text view and the width of the scroll view's bounds. And that's really too bad.
I don't actually recommend installing a fixed-width constraint on the text view. Instead, I would start over and use Apple's "mixed approach" from the Technical Note.
With the mixed approach, the subviews' constraints don't determine the scroll view's contentSize. Instead, you must explicitly set the scroll view's contentSize and the frame of a container view (i.e., a UIView content view).
Let's go back to that UITextView and the horizontal axis. Using the mixed approach, you could leave the constraints for the text view as they are (i.e., no fixed-width constraint). You could explicitly set the width of the scroll view's contentSize and the width of content view's frame as early as viewDidLoad. You could explicitly set these values to self.view.bounds.size.width because your scroll view hugs the sides of the main view.
To implement the mixed approach, you will have to instantiate the content view (UIView) in code and not set its translatesAutoresizingMaskIntoConstraints property to NO. By extension, you'll probably need to create your constraints for all those subviews in code as well (I don't know of any way around this). The visual formatting strings are tedious and repetitive, but they're actually easier to work with than constraints created in IB when configuring complex layouts (your layout is sufficiently complex).
I used the mixed approach to solve a SO challenge here: https://stackoverflow.com/a/21770179/1239263. Unfortunately, the solution hasn't been vetted yet. It's always possible that I'm nuts and I don't know what I'm talking about.