I am a little stuck with the ScrollView in Swift and Xcode 11.
My goal is a simple ScrollView with Labels and Textfields. Each label describes what the textfields are used for. For example there is a Label "Name", so you have to enter your name in the textfield under the label. For this I need a ScrollView because the App I am coding requires a few more information. When I am trying to put this in a ScrollView I am constantly getting the following error:
"Scrollable content size is ambiguous to ScrollView".
In order to find help I searched the internet and for example found this question: UIScrollView Scrollable Content Size Ambiguity.
Unfortunatly it didn't solve my problem. So I decided to create a small test project with the following:
- I created a project as a Single View Application
- I added a ScrollView to the ViewController
- I clicked on the constrains-Button at the canvas
- I selected 0,0,0,0 for leading/top/trailing/bottom.
- I clicked on "add 4 Constrains
- Now the warning appeared. Also the ScrollView was not resized to the ViewController... I don't know why.
- I added a UIView inside the ScrollView and set the same constrains, this time according to the ScrollView.
- The UIView (Content view) got an extra constrain: Equal width with the root view
- Now I added two Buttons, one with the text "Hello" and the other one with "world" on it.
- The "hello"-Button received the following constrains: 16 to leading, trailing and top, as well as a fixed height of 30.
- The "world"-Button got the following constrains: 16 to bottom, leading, trailing and over a 1000 so you can scroll through the ScrollView.
After all these steps the error is still there and if I run the app the "hello"-Button is at the top of the screen and the "world"-Button is at the bottom and I can't scroll.
Can maybe anyone help me fixing this issue. I am looking forward to every answer! Thank you for your help in advance!
Here is the trick that worked for me:
Add a ScrollView to your wished ViewController.
Select it in the Outline and open its size inspector.
Uncheck there the option "Content Layout Guides".
Now set leading/top/trailing and bottom constrains to 0 of the ScrollView.
Add in a UIView and constrain its leading/top/trailing and bottom also to 0.
Add an equal width constrain to the UIView. (The width needs to be equal the width of the view from the ViewController, with this way you are disabeling horizontal scrolling).
The warning will disappear if every element inside the UIView is chained vertically. This means, that the top element has a constrain to the top of the view and to the element under it and so on. The last element needs a constrain to the bottom of the view.
If you followed this steps you should be fine with ScrollViews. This way you also can add as many content as you want to the bottom and the ScrollView will extend dynamically.
I hope I explained it well enough.
It sounds like you're on the right track, and really close.
The first part is absolutely right - you add your ScrollView and pin it to zero for the top, trailing, bottom, and leading constraints. That makes it take up your whole screen.
Then you drop a plain old UIView into the ScrollView, and pin its top, trailing, bottom, and leading constraints to the ScrollView (all as zero again). Then you set the UIView to have an equal width to the ScrollView. The last thing is to set the UIView's height as equal to the ScrollView's height, but you change one thing: you set the priority of this constraint to be low (250). That's basically what allows the UIView to exceed the size of the ScrollView, so you can then scroll.
All you do then is add your buttons, etc inside the UIView, so you place them in relation to it rather than the ScrollView, and pin or align them as you wish.
Add a total of 9 constraints
1 - 4: ScrollView to Superview (leading, top, trailing & bottom)
5 - 8: Content view to Content Layout guide (leading, top, trailing & bottom)
9: Content view Width equals width to Frame Layout Guide.
But when you do this (right-click drag and drop) 7 & 8 constrains (trailing & bottom constrains to Content Layout guide) will have constant values. (check image below).
Just make them zero. Now it worked.
Related
I have a view hierarchy that looks like this (based on other answers and Apple's advanced AutoLayout guide for working with UIScrollView):
The 2 steps required for ScrollView are:
Set up constraints for position and size (frame) of ScrollView: The same way you do it with any other view.
Set up constraints for content size: By making sure that there are constraints from the ScrollView's subviews touching all edges (leading, trailing, top, bottom) of the ScrollView, if you're doing this in interface builder and not programmatically.
Step 1 worked fine at first and this was the result:
No problems with position and size as expected. I just need to define the content size (content height and content width) now in Interface Builder with Step 2.
Now I add the constraints touching all 4 edges of the ScrollView like so:
Suddenly, the ScrollView doesn't know it's position and size (frame) anymore.
I've looked at other answers and followed the various steps, but can't seem to resolve this issue. Sorry I'm not able to post Storyboard screenshots because of privacy issues
Set the scroll view's top, bottom, leading, trailing constraints to its superview to 0.
Set the view that is inside the scroll view and set its top, bottom, leading, trailing constraints to its superview to 0.
Select the view that is inside the scroll view, go to the size inspector and set the "Intrinsic size" to "Placeholder".
Scroll views can be a little tricky at first. You really have 3 parts:
Actual frame of the scroll view
Actual frame of the subview(s) contained in the scroll view
The contentSize of the scroll view - that is, how far it should scroll in either direction
So, 1. is pretty straight-forward.
The second part also seems straight-forward, except that we tend to "pin" subviews to the inside edges of their superviews. In the case of scroll view subviews, those constraints are what defines the contentSize. You also have to make sure the subviews have a "size".
Starting with just one subview, you would:
set the scroll view's constraints as "normal".
set the size of the subview - just for demo purposes, set it to 100 x 100
pin all four edges of the subview to the four edges of the scroll view
Run the app. Assuming you set background colors so you know what you're looking at, you should see the scroll view positioned and sized as you'd expect... you should see the subview of 100 x 100 sitting somewhere inside the scroll view... and you will likely not be able to do any actual scrolling.
If you go back and change the subview to, say, 100 x 800, and still have its bottom constraint pinned to the bottom of the scroll view (the subview's superview), and run the app again... You should be able to scroll up and down for the full 800 pt height of the subview.
The way to think about it is: the scroll view's content - whether it's one or many subviews - has to define its own size, which will define the scrollable area (the scroll view's contentSize).
Hope that makes sense!
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)
My problem is slightly different from other's 'Swift UIScrollView' problems when using auto layout:
Problem:
Unlike others, when I run my app, it scrolls. My problem is that the scroll cuts off the bottom 20-30% of the content. I can pull to see the buttons did build and are down there, but when I let it go the scroll snaps back to a false bottom which cuts off my content!!! I've been trying, for days, to fix it to scroll the entire height but it continues to cut off!!
Description of app:
I used auto layout to layout 6 buttons and labels. Each button a rectangular image, with a label directly beneath it. (sorry, the site won't let me post pictures!)
I have my views arranged like this:
MainView > ScrollView > ContentView > Buttons & Labels
I have my contentView pinned to my ScrollView and my ScrollView pinned to my MainView. My buttons and labels all have constraints that are building correctly, to create a list that looks like:
Rectangular button
Label beneath it
Spacing
Rectangular button
Label beneath it
Spacing
Etc.
Can anyone tell me why I can't scroll the full length of the view?
Your description of how your items are constrained is vague, so I'm going to list all of the constraints you need to make this work. Then you can compare what you have to what you need and adjust accordingly.
Your ScrollView should be pinned on all 4 sides to the MainView. (This isn't absolutely necessary. You can constrain your ScrollView however you want, but make sure it can grow as the device and/or orientation changes).
Your ContentView should be pinned on all 4 sides to the ScrollView with offsets of 0.
Since you want your ScrollView to scroll vertically only, constrain the width of the ContentView to the width of the ScrollView using an Equal Widths constraint. To do this, in the Document Outline view, Control-drag from your ContentView to your ScrollView and select Equal Widths from the pop up.
The height of ContentView will be set by the sum total height of everything in it. In order for this to work, your topmost button needs to be pinned to the top of the ContentView, all of your buttons and labels should be pinned to their nearest neighbors, and the bottommost label should be pinned to the bottom of the ContentView. In addition, all of your buttons and labels should have constraints for their widths and heights. I would suggest setting an explicit width constraint and explicit height constraint for your buttons and centering them horizontally in the ContentView. For your labels, set an explicit height constraint and pin the left and right edges to the ContentView.
If you have these constraints and no other ones, your ContentView will be properly sized.
Using contentView, like you said, usually fixes the issue. So chances are you need to take a second look at your contraints. Maybe try this solution in a clean/new project to see that it works. (it does work). My guess would be that some of your constraints conflict each other.
Otherwise I think it would be a good idea to setContentSize of your scrollView in your viewDidLoad.
Another hack would be to place 2 UI objects with their alphas set to zero on the right top corner and left bottom corner. This would hint scrollView to set its contentSize.
Hi I am developing small IOS application in which I am using scrollview with auto-layout.Inside scroll I am adding two more views. I am using IB and auto-layout constraints. I am adding two views in side one after another in vertical manner. I have added outer constraints like trailing, leading, top, bottom space. I also added height constraints for both views. Till this everything is working fine.
But my view1 has some dynamic content. For that reason I want to make height constraint greater than equal to instead of equal to.
So how to resolve this problem. Need some help. Thank you.
You should follow the approach below.
First of all, here are some important things about scroll Views which are important for auto layout:
UIScrollView changes its bounds automatically.
UIScrollView needs a content View(in UI) for getting content size for scrolling which works smoothly for auto layout.
UIScrollView's top and bottom constraint should connected to top and bottom layout guide (For most of the cases, not all).
As per your problem:
First Approach: You have UIScrollView, so just insert one UIView inside it and consider it as Content View. After that put your two UIViews inside the UIView (Content View).
So the Hierarchy is: MainView --> UIScollView --> UIView (ContentView) --> firstView & Second View. Now we are going to give constraints to all of them.
For UIScrollView, connect TOP and BOTTOM constraints to TOP & Bottom Layout Guide and LEADING and TRAILING to the Main View.
For UIView (Content View) it is very important to give constraints LEADING, TRAILING, TOP, BOTTOM to the UIScrollView and to give the explicit height (normal height constraint) to your contentView which is appropriate for scrolling (e.g 1200). Also make it horizontally center in container.
Now give constraints to your first view: LEADING, TRAILING, TOP to ContentView and give explicit height (normal height constraint). Don't try to modify it in greater than equal right now - we will do this later. Then, give constraint to second view Leading, Trailing to ContentView, Top to FirstView, Bottom to Content View and Explicit Height (what ever you want). Now, try to modify the Height constraint of first view from equal -> greater than equal - it will definitely work.
Second Approach (Easy and Simple): After giving constraint as per first point, for changing height of first View dynamically you can create an IBOutlet of height constraint of first view to your class and as per your requirement you can change the constraint's constant value (as per you want the height of first view) in any method or button action so it will change in run time. You can also consider it is a fine trick when you want to hide your views so just change their Height constraint's constant to 0 so it will hide and at the time of unhide, again set the constant value of same to desired value so you can also easily play with hide and unhide functionality of view which is little bit difficult in auto layout from other ways.
I would make this constraint as type equals and give it low priority. Then, during adding dynamic content, you may just add another constraint with higher priority.
If you load this UIView from xib just make sure you provide constraint with higher priority.
I've created a simple view setup in interface builder. Here's how it looks:
The view hierarchy is simply:
view
- scrollView
-- label
The scroll view is shown with grey background anchored to its super view top, leading, trailing, and bottom with constraints of 0.
The label is shown with yellow background and has constraints as shown. Additionally, the label has content hugging priority of 1000 for both horizontal and vertical, and it has content compression resistance priority of 1000 for both horizontal and vertical.
In portrait orientation, the label is sized correctly:
In landscape orientation, however, the label is not sized correctly horizontally (I intended for the label to fill the width of the screen, less constraint insets as shown):
How can I get this label to size correctly horizontally in landscape orientation?
There is one solution for you.
1. Add your UIScrollView to container (UIView) with zero constraints:
2. Add constraints for Label: top, bottom, leading, trailing spaces = 20.
3. Add constraint: label.width = container.width - 40
For this, select label in the view structure tree, tap ctrl and pull
to container. And select Equal Widths.
Then select the created constraint and go to its Utilities and set
the constant value to 40.
You should get the following components:
Run the app, go to landscape and it works!
Hope it is clear. Best Regards.
It's hard to tell which constraint(s) to add/remove in order to get what you want because iOS reserve the right to adjust your constraints whenever it becomes impossible for it to satisfy all your constraints.
I make a blank project with the same view you have (UILabel as subview of UIScrollView) and make some constraints to get the UILabel resized properly on landscape.
A must check though:
Make sure you set the vertical/horizontal spacing constraints from the pin option, as shown below and try to remove unneeded constraints manually.