I have pretty straightforward requirements where two labels must be centered horizontally. So, I have selected them and chose Editor->align->center horizontally. Then added top space to container constraint to both of them. I also need the labels to shrink/grow regarding content size. However, IB shows errors and several warnings. I could make the labels shrink/grow just by adding pin between them (horizontal space) but they will not be centered in that case. Here are the screenshots:
here are the errors and warnings:
UPDATE theraven gave an interesting suggestion to use dummy view for centering it horizontally and pinning two labels to it. I have removed all existing constraints, added this dummy view and center X + center Y constraints to it. Then pined two labels to it (added horizontal space constraints). However, I still get a bunch of errors and warnings:
UPDATE2 Just updating the question, but still no valid answer found. #Theraven workaround works for iPhone4, iPhone4S, iPhone5 and iPhone5S, however it's not real centering but rather a workaround. Therefore for iPhone6 and iPhone6 Plus it doesn't work as leading and trailing spaces will be fixed and won't automatically resize for larger width.
What you could do is add both labels to another view, like a container view. Then you need to center this one horizontally and add the necessary constraints.
To add the containing UIView, you can select both labels, go to Editor -> Embed In -> View.
Then you would need to add constraints to make the containing view fit the two labels. So something like this:
First Label (left one):
Leading Space to Superview
Top and bottom Space to Superview
Horizontal spacing to the next Label
Second Label:
Trailing space to superview
Top and Bottom to superview (or align top with the first one)
Then the containing view should resize as to fit both labels. Then all you need to do is add the top offset constraint for this container view and a horizontal alignment it in the parent view.
This way, the containing view will grow as much as it needs to fit both labels and the space between them and will always be centered in the parent view.
I took a screenshot of my test constraints in case it helps you more.
Hope this was what you were looking for.
To solve this use a blank UIView in between your two labels and center it horizontally. Then pin the two labels either side of the centered blank view. It is common convention to use spacer views like this in auto-layout.
I really don't like the idea of adding another view just for sake of estethic.
Another alternative is to horizontally-center the left view, and horizzontally space the right view of an amout X with the left one.
Then to give the horizontally-align contraint of the first view a negative value equal to the first view width plus half the views distance. Or use multipliers as said in a previous comment.
But this only works with fixed width views i guess.
Use centered UIStackView as a container for two labels with a spacing required.
I didn't really understand what you wish to do.
The error you get (in the first screen shot) is that you are missing constraint for the x position of the labels.
For UILabel you must have constraint both for y and for x position regarding to the container view, when you selected them both and chose Editor->align->center horizontally, you just say that label1.center.x = label2.center.x.
You still need to say where they will be in the container view, you added the top space to container, so you do have the y position, but you didn't say where the x position should be.
You said
I have pretty straightforward requirements where two labels must be centered horizontally
But where they should be in respect to their container?
thanks
Using spacer views is the best possible solution I could figure out, even though it looks ugly for the developer. The user wouldn't even know what's going on behind the scenes and once you have the spacer UIView, you can always reuse it.
Related
I am trying to create three containers (UI Views) as in the following example:
As you can see, in my case the TopContainer (the orange one) and the BottomContainer (the red one) have different dimensions. Also, I have a MiddleContainer (the white one) which is NOT located in the middle of the screen or in the center. In fact, the BottomContainer is a bit larger than the TopContainer.
Question: how can I keep them constrained no matter which phone my user has?
I tried to constraint the three components to the margins and between each others but it's not enough because, in that case, XCode argues that for each component the height and the width are ambiguous. Therefore I tried to maintain also the Aspect Ratio for all the three components and it seems to work, but with iPhone X (like iPhone XS) I get a ugly bottom line, so the bottomContainer doesn't fill the whole screen.
I know that there should be a "Bottom Space to" to set up for my BottomContainer in order to solve this issue but apparently I have it not, as you can see on the right side of the following screenshot:
Do you have an idea of what I am doing wrong? Do you have an alternative way to proceed?
I would solve it with a UIStackView with two UIView (orange and red). The UIStackView is set to distribute Fill Proportionally.
The orange view is the size of your orange view plus the size of the white view.
Then I'd add the white view as a child to the orange view and constrain it to the bottom of that view and with a fixed height.
To get rid of the bottom gap, set the bottom constraint to Superview instead of Safe Area.
See the screenshot for details:
As per your comment, I think this is what you can do!
Align the "middleComponent" to the center vertically, to its superview.
Set the height to it, as you want to have a fixes height there.
Then pin the "topComponent"'s bottom to the top of "middleComponent".
Pin the top of your "topComponent" to the top of the superview.
Pin the top of your "bottomComponent" to the bottom of the "middleComponent"
Pin the bottom of your "bottomComponent" to the bottom of your superview.
All these views will have have their left and right pinned to the superview's left and right.
Hope this helps
I don't really understand constraints and have tried many different suggestions found online. All they seem to do is bunch everything up on top of one another or do nothing at all.
I have the following IPad application but I want it to work on any size device, mainly a IPod touch.
The page is simply two buttons that I want to remain the same no matter what screen they're on.
Any help on this appreciated.
It helps to think about points of reference that won't change with different screen sizes. Sometimes you want things on, say the top left corner so you just do constraints to the top and the left.
I'll give you two suggestions
Suggestion One
For your case, it seems like you might want to do constraints off centerY since you want them to be in the middle despite the screen size.
So I would make a constraint to "Center Vertically in Container" and then tap on the constraint and adjust it's value to negative or positive, so that way it's always X pixels above or below the centerY.
Now that's not going to be enough. it knows it's Y position but it doesn't know its height, width, or X position. So you need to add enough constraints to satisfy those.
A few examples:
X/Width: Two constraints to leading and trailing on each button OR Center horizontally and fixed width constraint. (again be careful with fixed width constraints since screen sizes can change, sometimes it's what you want though)
Height: Yeah just give it a height constraint in this case.
Note that this means no matter the screen size they'll always have the same gap between them (and maybe different gaps to the other edges).
Suggestion Two
Use a container view, either a stack view (fill, equal spacing, vertical alignment, a spacing value for gap between) or normal view.
You can make the view a fixed height based off the height and spacing between the buttons you want. Then simply center that container view horizontally and vertically on the super view.
Nonsuggestion
There are certainly other ways (like using buffer views with equal heights constraints. So you'd have an invisible view on top, a view in between and a view on bottom. and you'd give those equal heights constraints and align the buttons to the edges of the invisible views surrounding them. As long as you gave the buttons a fixed height this would work for vertical constraints) but I think these two would probably be the best.
I understand the old Struts and Springs method of aligning, sizing and distributing views in Interface Builder. However, I cannot seem to figure out how to evenly distribute views using auto layout with Xcode 5. There was a way to do it using Xcode 4, but that option is gone.
I have 7 buttons arranged in a vertical stack. On a 3.5" layout, it looks great. When I preview the screen in the 4" layout, all of the buttons remain tightly packed and there is a large amount of space below the last button.
I want them to stay the same height, but I want the space between them to be able flex so they can spread out across the screen.
I've been able to get the height of the buttons to flex and fill the space, but that is not my desired behavior. I would like to learn how to use Auto Layout to replace my old Springs behavior, but I can't seem to find any way to do it through Interface Builder.
I'm ok with the top button either being a fixed space from the top edge or a proportional space from the top edge, likewise for the bottom button and the bottom edge. Those are less important to me, I'm good with either.
But I really need to figure out how to evenly distribute the extra space between each of the items in the view.
EDIT Note that in iOS 9 this technique will become unnecessary, because a UIStackView will perform distribution automatically. I'll add another answer explaining how that works.
How to Perform Even Distribution Using Autolayout
The simplest way to do this in Interface Builder alone (rather than constructing constraints in code) is to use "spacer" views:
Position the top and bottom buttons absolutely.
Place spacer views between all the buttons. Use constraints to position them horizontally (centering them horizontally is simplest) and to set their widths.
Make constraints between each button and the spacer view above and below it, with a Constant of 0.
Now select all the spacer views and set their heights to be equal.
The first screen shot shows me setting this up in IB:
I have deliberately not corrected for the "misplaced views" because I want you to see what it looks like while I'm designing the constraints. Here's the result on both a 4 inch and a 3.5 inch screen:
I have left the spacer views black, just to show you how this technique works, but of course in real life you would make them transparent and hence invisible! So the user sees just your buttons, evenly distributed on either height of screen.
The reason for the use of this technique is that although the notion of equality performs the distribution of values you are asking for, constraints can apply equality only between aspects of views; thus we need the extra views (the spacer views) so that we have things we can make equal to other things (here, the heights of the spacer views).
Other Approaches
Obviously, a more flexible approach is to assign the constraints in code. This may sound daunting, but there's a lot of third-party code out there to help you, such as this sort of thing.
For example, if we have a (possibly invisible) superview whose height acts as a boundary to dictate maximum vertical distribution of our four buttons, we can pin their tops to the vertical center of that superview with a constant of 0 but a multiplier of 0.000001, 0.666667, 1.33333, and 2.0 respectively (if we have four buttons); now the buttons will stay vertically distributed even as the superview changes size in response to screen height or whatever. [In Xcode 5.1, it will be possible to set that up in Interface Builder, but in earlier versions of Xcode it is not possible.]
In iOS 9 / Xcode 7 this problem will be trivially solved in IB. Simply select the buttons (or whatever it is you want to distribute vertically) and choose Editor > Embed In > Stack View. Then you simply configure the stack view:
Provide constraints that position and size the stack view itself. For example, pin the four edges of the stack view to the four edges of its superview.
Set the stack view's attributes. In this case we want Vertical axis, Fill alignment, Equal Spacing distribution.
That's all! However, you may be curious about how this works, because it is still possible to do the same thing manually in code. A stack view performs distribution, not by inserting spacer views, but by inserting spacer guides. A guide (a UILayoutGuide) is a lightweight object that behaves like a view for purposes of layout constraints, but is not a view and therefore doesn't have to be made invisible and doesn't carry any of the overhead of a view.
To illustrate, I'll do in code what the stack view is doing. Presume we have four views to distribute vertically. We assign them constraints for everything but their distribution:
They all have absolute height constraints
Their left is pinned to the superview's left, and their right is pinned to the superview's right
The top view's top is pinned to the superview's top, and the bottom view's bottom is pinned to the superview's bottom
Now, presume we have references to the four views as views, an array. Then:
let guides = [UILayoutGuide(), UILayoutGuide(), UILayoutGuide()]
for guide in guides {
self.view.addLayoutGuide(guide)
}
NSLayoutConstraint.activateConstraints([
// guide heights are equal
guides[1].heightAnchor.constraintEqualToAnchor(guides[0].heightAnchor),
guides[2].heightAnchor.constraintEqualToAnchor(guides[0].heightAnchor),
// guide widths are arbitrary, let's say 10
guides[0].widthAnchor.constraintEqualToConstant(10),
guides[1].widthAnchor.constraintEqualToConstant(10),
guides[2].widthAnchor.constraintEqualToConstant(10),
// guide left is arbitrary, let's say superview margin
guides[0].leftAnchor.constraintEqualToAnchor(self.view.leftAnchor),
guides[1].leftAnchor.constraintEqualToAnchor(self.view.leftAnchor),
guides[2].leftAnchor.constraintEqualToAnchor(self.view.leftAnchor),
// bottom of each view is top of following guide
views[0].bottomAnchor.constraintEqualToAnchor(guides[0].topAnchor),
views[1].bottomAnchor.constraintEqualToAnchor(guides[1].topAnchor),
views[2].bottomAnchor.constraintEqualToAnchor(guides[2].topAnchor),
// top of each view is bottom of preceding guide
views[1].topAnchor.constraintEqualToAnchor(guides[0].bottomAnchor),
views[2].topAnchor.constraintEqualToAnchor(guides[1].bottomAnchor),
views[3].topAnchor.constraintEqualToAnchor(guides[2].bottomAnchor)
])
(Obviously I could make that code cuter and shorter using loops, but I have deliberately unrolled the loops for clarity, so that you can see the pattern and the technique.)
I implemented a viewcontroller similar to the one in this question:
iOS two views cover exactly half of parent view
I get the desired result. The problem is that when I add a UIImageView into those two containers, the result get resized and ruins the symmetry. How do I prevent Imageviews from changing the size of their containers? I need to use AspectFill for these images.
I don't think the containers' sizes are changed. You just need to set their clipsToBounds property to true to avoid overflow.
If you use Reveal you should see the containers' sizes are not changed even if pictures inside them are bigger than themselves.
I'm unsure I understand what you mean about adding UIImageView into those controllers causing the views to resize, so forgive me if I'm getting this all wrong...
It sounds as though you've created two views of equal height that, together, consume the entire vertical space of the screen. After having done that, you want to add one or more UIImageView's to each of the original two views. Unfortunately, when you add the UIImageView, the enclosing view is resized.
Assuming I have that correct...
Are you doing this with Interface Builder either in an XIB or Storyboard file? If so, you ought to be able to achieve this with the proper set of constraints.
In the following image, I've laid out what I describe above.
As you can see, I have a red view on the top half of the window and a green view on the bottom half. The red view contains a UIImageView that is 75% of the width and height of red view, with its origin at (20, 20) within the red view.
The scene is configured as shown below:
The constraints on "Upper View" are:
You can see from this that Upper View is flush with the left, right, and top of its superview, and that its space to Bottom View is 0. You'll have to trust me that Bottom View is set up the same way.
The height of the Upper and Lower views is "Proportional" as shown in this constraint:
To achieve this "Proportional" setting, you first make the height of Upper View equal to the height of the superview, and then edit the constraint, changing "Multiplier" from "1" to "0.5."
The height (and width) of the Image View is proportional to that of the Upper view, as shown here:
If you set it up this way, you ought to be able to accomplish what (I think) you are looking to accomplish.
If my original assumption of what you are trying to achieve is incorrect, please post images of what you've got and how it's not working.
I am creating a view within IB and and attempting to have 3 UILabels evenly space horizontally across the view. I came across this on SO, https://stackoverflow.com/a/30249550/4597666. I have three UILabels, each have the height and width constrained. Here is what the IB looks like:
I constrained each centered horizontally, and the first UILabel I have the multiplier 3:1, second, 3:3, third 3:5 like the post states.
When I run on my emulator, I don't get the result that I was expecting. It appears all three UILabels are centered horizontally, and the first and third are not offset.
Is there another setting that I'm missing, or another way to properly space the views evenly?
you need to make only one change.
Constraint you set is 3.CenterX to Superview.CenterX all you need to do is interchange the value so that you constraint should look like in below image.
Alternative solution. If you want to set constraints currently you have set then change the ratio from "3:5" to "5:3" and similar for all the labels.
Result:
Hope it helps you solving your problem.