I followed Apple website's guide for Swift
https://developer.apple.com/library/content/referencelibrary/GettingStarted/DevelopiOSAppsSwift/BuildABasicUI.html#//apple_ref/doc/uid/TP40015214-CH5-SW1
After I placed the 3 objects on the drawing board and stacked them, it aligned with the left margin nicely but after I set the constraints for adaptive interface, it aligns with the very edge of the screen. Any help?
https://i.imgur.com/eRH9Wor.png
but after I set the constraints for adaptive interface, it aligns with the very edge of the screen. Any help?
You just haven't configured the constraints properly. It's hard to say exactly what you've done wrong without seeing how your constraints are set up, but I can give an example of what they should look like. Here's a button in a view, constrained so that the button is inset 20 pixels from the top and leading edges of the view. With the button selected in Interface Builder, we can see the constraints:
And looking at the constraints in the Size inspector:
(The button looks a little different from what you might expect because this happens to be a macOS project, but the constraints work exactly the same way as they do in iOS.)
Related
I am extremely bad at creating layouts for multiple screen orientations. All along I've been using suggested constraints on Auto-Layout but sometimes they don't work as desired. I've been trying to learn how set up my layouts properly by reading and watching tutorials, but I still cannot understand how exactly constraints work!
What I am trying to do is to make the button widths equally like so in iPhone 7:
But on other devices such as iPhone 4S, the second button width shrinks, which is not what I wanted:
Can someone please explain to me how constraints work in layman terms? I do not understand things like:
Leading/Trailing Space
Constrain to margins
Equal Widths and Heights
Top, Bottom, Baseline etc. (What do they even mean?)
Here's how to make two equal-width buttons:
Create two buttons
Add a vertical position constraint to each button. For example, you could position them in the center of the parent view using the "Align->Vertically in Container" function (in the lower-lefthand corner of the interface builder window)
Select both buttons. Add an equal width constraint between them using "Add New Constraints->Equal Widths"
Constrain the left edge of the left button to the leading edge of the parent view
Constrain the right edge of the left button to the left edge of the right button. Add space between the buttons using the "Constant" property of the constraint you created.
Constrain the right edge of the right button to the right edge of the parent view
Hope that helps! 😀
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.)
Hey, I'd like to obtain what you see in the pictures: in Compact Height mode (landscape iphone) both the red and the blue view have to take all screen vertically and half the screen horizontally. In Compact Width mode (portrait iphone)they have to take all the screen horizontally and half the screen vertically. Space between views should be same size in both modes.
I used to think I have to use size classes and auto-layout constraints, but everything I tried failed miserably.
Maybe I have to use a UICollectionView and change flow direction based on orientation (if that is even possible)?
A collection view is probably overkill, because you don't want scrolling and that's the whole point of a collection view--by the time you do the sizing to stop it you'll have done all the work necessary to set a non-scrolling layout.
This is possible with Size Classes in IB. First, In general you will probably find it helpful to name the views in the Document Outline on the left in IB. You will also want to use this outline rather than try to grab the tiny constraint H-lines.
Set up all the constraints except 1) constraints linking the
OrangeView and BlueView to each other, 2) the constraints linking
the OrangeView to the top and left(leading), and 3) The constraints
linking the BlueView to the bottom and right (trailing).
Change the size class setting at the bottom to w-Compact and
h-Any in the funky box system. Now we're designing for a compact width, so views on top of each other.
Create a constraints for vertical space for BlueView.bottom to
OrangeView.Top. Also create constraint for OrangeView to
superview.leading (or ledaing,margin) and BlueView to
superview.trailing.margin. If you select any one of these constraints and look at the Size Inspector on the right (the ruler) you should see an "installed" checkbox not selected, and below that a w-Compact h-Any and another installed box, this one selected.
Now, while keeping the constraint selected just to see what happens, change the sizeClass selector at the bottom to w-Regular h-Any. Notice that in the Document Outline to the left, it should get grayed out.
Now we are designing for regular, so side-to-side. Add constraints linking the views for horizontal space, BlueView.trailing to OrangeView.leading. Also link OrangeView.top to the superview.top or top aligned to BlueView.top, and same for bottoms. You can manually edit the frame first; if not, IB will automatically fill in the wrong values, so edit these after you create them, and verify they are w-Regular and h-Any. With the ViewController selected, select "update frames" and the views should snap to their expected shape for the size class.
Let us know if this works for you or if it was unclear. Good luck!
I’m having bit of a tough time getting my head around auto layout, constraints, priorities, compression and content hugging.
I think I understand it but getting it to play nicely seems to be impossible.
I have this simple view, with 3 buttons and a label.
I want them to be able to adjust to fit the screen when the user orients the screen.
All the buttons are pinned to the leading and trailing superview.
The top label’s top is pinned to the super view. The bottom button’s bottom is pinned to the superview.
There are vertical space constraints between the buttons.
I have tried varying priority levels for the compression of the buttons to get them to squeeze vertically for the horizontal view, but everything disappears off the screen.
Or one of the lower buttons appears above the upper buttons.
I am sure I am doing something quite simple to make these errors.
Would someone be able to offer me their 2 cents on how to fix this?
Many thanks for any help!
Merry xmas!
Adam
UPDATE - after "update all frames"
It seems button 01 disappears when the view is rotated
**UPDATE #02 - almost working but not sure how **
Guys I seem to have managed to get it to work, but i'm not really sure how.
And it's not reliable - if I adjust the constraints between the label and the first button then the oriented view ends up scaling off out of the bounds of the screen.
I would assume that I could adjust that vertical constraint to be able to change that space, but it just makes a mess.
Pin the bottom button to the view controller's bottomLayoutGuide, not the superview. Do this by control-dragging from the bottom button to the Bottom Layout Guide in the scene's Document Outline.
Also, your interface objects are misaligned; that is, the frames don't match the constraints (or the constraints don't match the frames). That's why you see the dashed rectangular outlines. Go to the floating tool bar in the lower-right corner of the storyboard canvas and click on the "Resolve Auto Layout Issues". From there, either select "Update All Frames…" or "Update All Constraints".
I think the default values for compression resistance and content hugging priorities are adequate.
I am trying to learn to use layout constraints in interface builder but I am running across an issue...
I've got two views, one UILabel and one UIImageView, and I'd like a layout as follows:
the label should be centered in the superview
the imageview should be a set distance to the left of the label
Seems pretty simple, but I can't figure out how to impose a constraint for the second condition (the first is done automatically). Anyone know how to do this?
Thanks!
Click on both views while holding the command key so they're both highlighted. Then click on the pin button in the bottom right hand corner of IB (the middle button). Select horizontal spacing and the constraint should now be added. You should be able to adjust it as needed from there.