I have a view with a UIButton on it. I've added two constraints:
Leading space to superview of 16
Top space to top layout of 265
Depending on which device I look, the button is in different locations. The only way that I can get it consistent is to center it. As a result, I've been building views off of a centered subview by setting vertical and horizontal distance.
I know that these constraints are actual number values and that the different iOS devices have different screen sizes. How can I set it up so that the button will appear in the same location, relative to each device's screen size? For instance, if I have a button positioned a quarter of the way down the screen, how can I ensure that the button shows up a quarter of the way down the screen on all devices?
I feel like entire books could be written about how to set up screens with auto constraints.
A solution, without code, could be to :
Put the button in an UIView. Set the height of that view to be equal to the height of the controller's using an equal height constraint. Set the multiplier of that constraint at 3/4. Also add leading, trailing and a bottom constraints to the view. Now put your label in the view and pin it in the view with leading, trailing, top and bottom constraints. Done. If you're targeting iOS 9, use a LayoutGuide rather than UIView.
A more appropriate solution could be done with code : create an IBOutlet of the top constraint of your button in your controller. Change the constant of that IBOutlet in ViewDidLoad: method to self.view.frame.height / 4.
Related
Basically I have one view with some height x
and 4 other views with same height y all these 5 views are vertically one after another with 10 px space
all these views have again some child views which depends on them.
For this scenario stackview is ideal but it support starts from iOS 9 unfortunately I have to support from iOS 6
so basically I fixed all the views with leading,trailing,top,bottom and height constraint...
it works good in iPhone 7s ... but in iphone 4s the view gets overlapped on each other
in iphone se the views are very much congested..
I was always thinking the height will change according to the screen size for iPHone 4s but that didn't happen
How can I work this out ?
There are two ways to solve the problem you are facing.
First:
Instead of giving a fixed height to any of your UIView you can use a proportional height constraint. Select your UIView and control + drag from your UIView to the main superview. Select equal height constraint. Now, double click the height constraint and set the multiplier to 0.15 or any value you seem nice. This will ensure the view thus created is always 0.15 times the entire view's height. Now you can create your other views either proportional to this view following the same steps or to the superview.
Second:
(I prefer this approach as for items as sometimes you need to create forms the above approach might still push elements off the screen).
This will use a UIScrollView. To your main view add a UIScrollView and add a leading, trailing, top and bottom constraint to your superview. Add a UIView to this UIScrollView and give it a leading, trailing, top and bottom as well. Additionally give it a equal height and width constraints to the superview of the UIScrollView with a low priority of like say 250. Now add all your elements inside this UIView however you seem fit. With fixed height, proportional height whatever and happily run it. But ensure you add a bottom of >= a minimum value for your bottom most view.
The screen will automatically become scrollable if the content will go off screen otherwise it won't be scrollable at all.
fixed all the views with leading,trailing,top,bottom and equal height constraint instead of only height(not give fixed height to any view)
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)
In my UIViewController I put a UIScrollView and attached constraints:
Then I added a view to this scroll view with following constraints:
and positioned it like this:
so as you can see it is quite long. When I run the app I can scroll it just for couple pixels instead of completely to the top of the screen. I want to make it possible to scroll it to the top so that it can cover everything what's under it. So what am I doing wrong here?
========= EDIT
for clarification - I want to achieve an effect that when user opens this screen, 10% of the screen is covered by the view. User can slide up this view and then it covers 90% of the view. And he can slide it down back to the 10%. Can you help me with adjusting constraints so that it looks good on every screen size?
Take a UIView inside the UIScrollView.
Set the constraint for scroll view as leading, trailing, top, bottom.
Select UIViewController in the story board and click size inspector then choose freeform then set the view height as bigger.
Then set constraint of UIView is leading , trailing , top , bottom as 0, so that the UIView will be same as ScrollView region. Now set height constraint something bigger so that you can design image view, label 1 and label 2. Then set constraint like the image view : top to UIView, leading , trailing and height.
For label 1: leading, trailing , vertical to UIImageView, height.
For label 2: leading, trailing , vertical to label 1, height and bottom to UIView (Important as based on this content view will be set).
After setting constraint You can select UIViewControl from story board and set the SizeInspector as fixed as it was before.
It will show the screen as you need (Image view, below label 1 and on scrolling label 2)
I have tested it in my demo project.
Hope it helps
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.
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.