I am developing a swift application which will fit 10 items on the screen. If I wanted to do this on a screen that would not change size i.e. the user doesn't change orientation or an iPad user does not use split screen, I would be able to detect the width by doing let size = bounds.width/19.
The problem is as the screen size is dynamic so therefor I need to do it with constraints. I would not like to use UICollectionView as that is too heavy and would also not like to use UIStackView if possible as I don't think it supports aspect ratio which I need for circles. I am trying to use UIViews.
Edit:
This is how I want them to look. This will be about 50 high and other information will be underneath.
UIStackView is the right tool for this job. In the future, I recommend more rigorously defining what you want to happen first, then dive into the documentation.
let sv = UIStackView()
sv.spacing = 10
// this means each arranged subview will take up the same amount of space
sv.distribution = .fillEqually
for _ in 0..<50 {
// omitting the rounded corners or any other styling because
// it's not the point of this question
let subview = UIView()
// The stack view will determine the width based on the screen size
// we just need to say that height == width
subview.widthAnchor.constraint(equalTo: subview.heightAnchor).isActive = true
sv.addArrangedSubview(subview)
}
// add your stackview to your view hierarchy and constrain it
Related
(Xcode 11, Swift)
Being a newbie to iOS and Autolayout, I'm struggling with implementing a fairly simple (IMHO) view which displays a [vertical] list of items. The only problem is that items are decided dynamically and each of them could be either text or image (where either of those could be fairly large so scrolling would be required). WebView is not an option, so it has to be implemented natively.
This is how I understand the process:
Make in IB a UIScrollView and size it to the size of the outer frame.
Make a container view as a subview of UIScrollView (again, in IB) and size it the same.
Set constraint on equal width of both
At runtime, populate container view with UILabels/UIImageViews and also set constraints programmatically to ensure proper layout.
"Tell" scrollview about the subview height in order to make it manage the scrolling thereof.
Is this the right approach? It doesn't seem to work for me (for a toy example of dynamically adding a very tall image to a container view - I cannot get the scrolling to work). What would be the proper way to do the last step in the process above - just force the contentSize of the scrollview to the size of the populated container view (it doesn't seem to work for me). Any help would be appreciated.
When adding multiple elements to a scroll view at run-time, you may find it much easier to use a UIStackView... when setup properly, it will automatically grow in height with each added object.
As a simple example...
1) Start by adding a UIScrollView (I gave it a blue background to make it easier to see). Constrain it to Zero on all 4 sides:
Note that we see the "red circle" indicating missing / conflicting constraints. Ignore that for now.
2) Add a UIView as a "content view" to the scroll view (I gave it a systemYellow background to make it easier to see). Constrain it to Zero on all 4 sides to the Content Layout Guide -- this will (eventually) define the scroll view's content size. Also constrain it equal width and equal height to the Frame Layout Guide:
Important Step: Select the Height constraint, and in the Size Inspector pane select the Placeholder - Remove at build time checkbox. This will satisfy auto-layout in IB during design time, but will allow the height of that view to shrink / grow as necessary.
3) Add a Vertical UIStackView to the "content view". Constrain it to Zero on all 4 sides. Configure its properties to Fill / Fill / 8 (as shown below):
4) Add an #IBOutlet connection to the stack view in your view controller class. Now, at run-time, as you add UI elements to the stack view, all of your "scrollability" will be handled by auto-layout.
Here is an example class:
class DynaScrollViewController: UIViewController {
#IBOutlet var theStackView: UIStackView!
override func viewDidLoad() {
super.viewDidLoad()
// local var so we can reuse it
var theLabel = UILabel()
var theImageView = UIImageView()
// create a new label
theLabel = UILabel()
// this gets set to false when the label is added to a stack view,
// but good to get in the habit of setting it
theLabel.translatesAutoresizingMaskIntoConstraints = false
// multi-line
theLabel.numberOfLines = 0
// cyan background to make it easy to see
theLabel.backgroundColor = .cyan
// add 9 lines of text to the label
theLabel.text = (1...9).map({ "Line \($0)" }).joined(separator: "\n")
// add it to the stack view
theStackView.addArrangedSubview(theLabel)
// add another label
theLabel = UILabel()
// multi-line
theLabel.numberOfLines = 0
// yellow background to make it easy to see
theLabel.backgroundColor = .yellow
// add 5 lines of text to the label
theLabel.text = (1...5).map({ "Line \($0)" }).joined(separator: "\n")
// add it to the stack view
theStackView.addArrangedSubview(theLabel)
// create a new UIImageView
theImageView = UIImageView()
// this gets set to false when the label is added to a stack view,
// but good to get in the habit of setting it
theImageView.translatesAutoresizingMaskIntoConstraints = false
// load an image for it - I have one named background
if let img = UIImage(named: "background") {
theImageView.image = img
}
// let's give the image view a 4:3 width:height ratio
theImageView.widthAnchor.constraint(equalTo: theImageView.heightAnchor, multiplier: 4.0/3.0).isActive = true
// add it to the stack view
theStackView.addArrangedSubview(theImageView)
// add another label
theLabel = UILabel()
// multi-line
theLabel.numberOfLines = 0
// yellow background to make it easy to see
theLabel.backgroundColor = .green
// add 2 lines of text to the label
theLabel.text = (1...2).map({ "Line \($0)" }).joined(separator: "\n")
// add it to the stack view
theStackView.addArrangedSubview(theLabel)
// add another UIImageView
theImageView = UIImageView()
// this gets set to false when the label is added to a stack view,
// but good to get in the habit of setting it
theImageView.translatesAutoresizingMaskIntoConstraints = false
// load a different image for it - I have one named AquariumBG
if let img = UIImage(named: "AquariumBG") {
theImageView.image = img
}
// let's give this image view a 1:1 width:height ratio
theImageView.heightAnchor.constraint(equalTo: theImageView.widthAnchor, multiplier: 1.0).isActive = true
// add it to the stack view
theStackView.addArrangedSubview(theImageView)
}
}
If the steps have been followed, you should get this output:
and, after scrolling to the bottom:
Alignment constraints (leading/trailing/top/bottom)
The alignment constraint between Scroll View and Content View defines the scrollable range of the content. For example,
If scrollView.bottom = contentView.bottom, it means Scroll View is
scrollable to the bottom of Content View.
If scrollView.bottom = contentView.bottom + 100, the scrollable
bottom end of Scroll View will exceed the end of Content View by 100
points.
If scrollView.bottom = contentView.bottom — 100, the bottom of
Content View will not be reached even the scrollView is scrolled to
the bottom end.
That is, the (bottom) anchor on Scroll View indicates the (bottom) edge of the outer frame, i.e., the visible part of Content View; the (bottom) anchor on Content View refers to the edge of the actual content, which will be hidden if not scrolled to.
Unlike normal use cases, alignment constraints between Scroll View and Content View have nothing to do with the actual size of Content View. They affect only “scrollable range of content view” but NOT “actual content size”. The actual size of Content View must be additionally defined.
Size constraints (width/height)
To actually size Content View, we may set the size of Content View to a specific length, like width/height of 500. If the width/height exceeds the width/height of Scroll View, there will be a scrollbar for users to scroll.
However, a more common case will be, we want Content View to have the same width (or height) as Scroll View. In this case, we will have
contentView.width = scrollView.width
The width of Content View refers to the actual full width of content. On the other hand, the width of Scroll View refers to the outer container frame width of Scroll View. Of course, it doesn’t have to be the same width, but can be other forms like a * scrollView.width + b.
And if we have Content View higher (or wider) than Scroll View, a scrollbar appears.
Content View can not only be a single view, but also multiple views, as long as they are appropriately constrained using alignment and size constraints to Scroll View.
For details, you may follow this article: Link.
I want my view to have the following properties (the numbers are arbitrarily chosen):
width is equal to height divided by 1.2
stays at the bottom right of the screen
height is 1/7 of the screen's height when in portrait
width and height does not change when the orientation changes
The first three requirements can be easily translated into UILayoutConstraints. I have done them with SnapKit just because it reads more clearly. You should see what I mean even if you have never used SnapKit before.
let myView = UIView(frame: .zero)
myView.backgroundColor = .green
view.addSubview(myView)
myView.snp.makeConstraints { (make) in
make.right.equalToSuperview().offset(-8)
make.bottom.equalToSuperview().offset(-8)
make.width.equalTo(myView.snp.height).dividedBy(1.2)
make.height.equalTo(view.snp.height).dividedBy(7) // *
}
The problem is the last bullet point. When I rotate the device from portrait to landscape, what was originally the width before the rotation, becomes the height after the rotation. This causes my view to become smaller as a result.
Basically, I want to replace the constraint marked with * with something like this:
make.height.equalTo(max(view.snp.height, view.snp.width)).dividedBy(7)
but I don't think max(a, b) is a thing in SnapKit or the UILayoutConstraint API.
Surely there is some other way of expressing "equal to whichever length is longer", right?
P.S. I didn't tag this with snapkit because I would also accept an answer that uses the UILayoutConstraint API.
Looks like you have 2 options:
Hardcode the height value.
Try to use nativeBounds:
This rectangle is based on the device in a portrait-up orientation. This value does not change as the device rotates.
In this case the height is always be for portrait mode.
myView.snp.makeConstraints { make in
make.right.bottom.equalToSuperview().offset(-8)
let screenHeight = UIScreen.main.nativeBounds.height / UIScreen.main.nativeScale
let height = screenHeight / 7
make.width.equalTo(height).dividedBy(1.2)
make.height.equalTo(height)
}
My original ViewController consists of only one scrollView like this:
Now I also have my own xib file (CheckBoxView) which mainly consists of one button, see this screenshot:
I dynamically create some UIStackViews and add them to the ScrollView Inside these UIStackViews I add multiple instances of my xib file.
What I want to achieve is, that the StackViews are just vertically stacked. And inside the StackViews the UIViews from my xib-file should also be vertically stacked.
At the moment it looks like this:
So the xib-Views are not in the whole view. Since I am using multi-os-engine I can't provide swift/obj-c code. But here is my Java-Code:
for (ItemConfiguration config : itemInstance.getConfigurations()) {
List<DLRadioButton> radioButtons = new ArrayList<DLRadioButton>();
UIStackView configView = UIStackView.alloc().initWithFrame(new CGRect(new CGPoint(0, barHeight), new CGSize(displayWidth, displayHeight - barHeight)));
configView.setAxis(UILayoutConstraintAxis.Vertical);
configView.setDistribution(UIStackViewDistribution.EqualSpacing);
configView.setAlignment(UIStackViewAlignment.Center);
configView.setSpacing(30);
for (ConfigurationOption option : config.getOptions()) {
UIView checkBox = instantiateFromNib("CheckBoxView");
for (UIView v : checkBox.subviews()) {
if (v instanceof DLRadioButton) {
((DLRadioButton) v).setTitleForState(option.getName(), UIControlState.Normal);
//((DLRadioButton) v).setIconSquare(true);
radioButtons.add((DLRadioButton) v);
}
}
configView.addArrangedSubview(checkBox);
}
// group radiobuttons
//groupRadioButtons(radioButtons);
configView.setTranslatesAutoresizingMaskIntoConstraints(false);
scrollView().addSubview(configView);
configView.centerXAnchor().constraintEqualToAnchor(scrollView().centerXAnchor()).setActive(true);
configView.centerYAnchor().constraintEqualToAnchor(scrollView().centerYAnchor()).setActive(true);
}
private UIView instantiateFromNib(String name) {
return (UIView) UINib.nibWithNibNameBundle(name, null).instantiateWithOwnerOptions(null, null).firstObject();
}
How do I need to set the Alignments etc. to Achieve what I want. It should look like this:
I don't know if there is a reason to not use UITableView, that i highly recommend for your case. In case it's not possible, below you can find some pieces of advice that should help.
If you use Auto Layout, you should set constraints for all views instantiated in your code. The constraints must be comprehensive for iOS to know each view's position and size.
Remove redundant constraints
configView.centerXAnchor().constraintEqualToAnchor(scrollView().centerXAnchor()).setActive(true);
configView.centerYAnchor().constraintEqualToAnchor(scrollView().centerYAnchor()).setActive(true);
These two constraint just doesn't make sense to me. You need the stackviews be stacked within you ScrollView, but not centered. If i understand you goal correctly, this should be removed
Set width/x-position constraints for UIStackViews
configView.setTranslatesAutoresizingMaskIntoConstraints(false);
scrollView().addSubview(configView);
Right after a stack view is added to the ScrollView, you need to set up constraints for it. I'll provide my code in swift, but it looks quite similar to what your Java code is doing, so hopefully you'll be able to transpile it without difficulties:
NSLayoutConstraint.activate([
configView.leadingAnchor.constraintEqualToAnchor(scrollView.leadingAnchor),
configView.trailingAnchor.constraintEqualToAnchor(scrollView.trailingAnchor)
]);
Set height constraints for UIStackViews
StackViews doesn't change their size whenever you add arranged view in it. So you need to calculate a desired stackview size yourself and specify it explicitly via constraints. It should be enough to accommodate items and spaces between them. I suppose that all items should be of the same size, let it be 32 points, then height should be:
let stackViewHeight = items.count * 32 + stackView.space * (items.count + 1)
And make new height constraint for the stack view:
configView.heightAnchor.constraint(equalToConstant: stackViewHeight).isActive = true
Set y-position for UIStackView
This is a little bit more challenging part, but the most important for the views to work properly in a scroll view.
1) Change loop to know the index of a UIStackView
A scroll view should always be aware of height of its content, so you need to understand which stack view is the top one, and which is the bottom. In order to do that, you need to change for each loop to be written as for(;;) loop:
for (int i = 0; i < itemInstance.getConfigurations().length; i++) {
ItemConfiguration config = itemInstance.getConfigurations()[i]
...
}
I'm not aware of which type your array is, so if it doesn't have subscript functionality, just replace it with corresponding method.
2) Set top anchor for stack views
For the first stack view in the array, top anchor should be equal to the scroll view top anchor, for others it should be bottom anchor of the previous stack view + spacing between them (say, 8 points in this example):
if i == 0 {
configView.topAnchor.constraintEqualToAnchor(scrollView.topAnchor, constant: 8).isActive = true
} else {
let previousConfigView = itemInstance.getConfigurations()[i - 1]
configView.topAnchor.constraintEqualToAnchor(previousConfigView.bottomAnchor, constant: 8).isActive = true
}
3) Set bottom anchor for the last stack view
As was said - for the Scroll View to be aware of content size, we need to specify corresponding constraints:
if i == itemInstance.getConfigurations() - 1 {
configView.bottomAnchor.constraintEqualToAnchor(scrollView.bottomAnchor, constant: 8).isActive = true
}
Note: please be advised, that all constraints should be set on views that are already added to the scroll view.
UIStackView is awesome, I love Equal Spacing Distribution.
But how to achieve the same space also outside of elements dynamically?
In my case all elements will have same ratio 1:1
You can add equal spacing using the story board as shown here:
Source: https://stackoverflow.com/a/32862693/3393964
#Declan has the right idea. Here's that answer programatically where you add extra views on either side so the stack view gives correct outside spacing with any number of buttons.
stackView.alignment = .center
stackView.axis = .horizontal
stackView.distribution = .equalCentering
// Then when I add the views...
let leftView = UIView()
stackView.addArrangedSubview(leftView)
content.buttons.forEach { (button) in
stackView.addArrangedSubview(button)
}
let rightView = UIView()
stackView.addArrangedSubview(rightView)
Here's what my view looks like with 2 items using equalSpacing
And here it is with equalCentering distribution, also a nice look.
I prefer to let the UIStackView handle the spacing. Create a UIStackView with equal spacing and add two 0px wide (0px high if using a vertical stackview) transparent views to the the far sides of your stack view.
You can use constraints and give then same height and width. So when you change the dimension of anyone of the component then all components are changed with same dimension.
I think what you want is to have the same spacing outside of the stack view with the spacing outside.
What I would do is the put stack view inside another view (GRAY VIEW) and set the leading and trailing constraint of the stack view to be equal to the spacing of the stack view.
Spacing of the Stack View
Constraints of the Stack View from its super view (Gray View)
I've a fairly difficult layout design that might be easier using nested stack views in iOS. BUT, I'm having problems controlling the size or distribution of stacks nested inside other stacks. One part of the layout, for example, looks OK-ish if I set Distribution to Fit Equally:
BUT, what I really want is the photo and container to be about 1/3 the width of the text field stack. If I set Distribution to Fit Proportionally, the stack with the image (which doesn't change size) and container spreadout and squash the text against the side of the display. Everything I read suggests to reduce the Content Compression Resistance Priority. I've tried this on the image, the container and on the stack view itself, but it doesn't do much.
Could someone please point me in the right direction to control the relative widths of stacks nested inside other stacks?
To answer your question: Could someone please point me in the right direction to control the relative widths of stacks nested inside other stacks?
...
The problem is that your top-level UIStackView is asking for the intrinsicContentSize of all its subviews when determining how to divy up extra space/squash things together, based on each of the subviews' returned intrinsicContentSize and their contentHuggingPriority/contentCompressionResistance. Unfortunately, UIStackView itself - ie your nested UIStackView - doesn't return anything useful for its own intrinsicContentSize (despite it having its own subviews, which do). So the top-level UIStackView just ploughs ahead and lays things out as though the nested one doesn't care, which is why your nested UIStackView is ending up wider than you'd like.
I've had good luck by using a simple UIStackView subclass for the nested one which returns a useful intrinsicContentSize based on its own contents' widths (for a vertical axis) or heights (for a horizonal axis), as follows:
#implementation NestedStackView
- (CGSize)intrinsicContentSize
{
CGSize size = [super intrinsicContentSize]; // returns {UIViewNoIntrinsicMetric,UIViewNoIntrinsicMetric}
for (UIView *view in self.arrangedSubviews)
if (!view.hidden) { // UIStackView ignores hidden subviews when doing its layout; so should we...
if (self.axis == UILayoutConstraintAxisVertical) {
size.width = MAX(view.intrinsicContentSize.width, size.width);
} else {
size.height = MAX(view.intrinsicContentSize.height, size.height);
}
}
return size;
}
#end
By doing so, the top-level UIStackView now takes the nested UIStackView's desired content width into account when allocating its space. [aside: I first attempted adding an explicit NSLayoutConstraint on the width of the nested UIStackView, but it was just ignored. Whereas returning an instrinsicContentSize.width worked]
I'd hope there might be a better answer, but the only effective method that I've found is to put the image into a view and pin it to the view's edges. The size of the view can then be controlled with constraints.
If anyone has a better approach, they can still answer as part of this more detailed question:
https://stackoverflow.com/questions/33875801/how-to-position-and-size-images-and-their-frames-in-nested-stack-views-in-ib-w
One easy way to do this is to use AutoLayout to set relative width constraints on your nested stack views. For example, if you want to have your left UIStackView to fill 2/3rds of the screen and your right UIStackViewto fill 1/3rd, you can use the code below.
let leftStackView = UIStackView(arrangedSubviews: [...])
leftStackView.axis = .vertical
let rightStackView = UIStackView(arrangedSubviews: [...])
rightStackView.axis = .vertical
let containerStackView = UIStackView(arrangedSubviews:
[leftStackView, rightStackView])
containerStackView.axis = .horizontal
containerStackView.distribution = .fillProportionally
containerStackView.translatesAutoresizingMaskIntoConstraints = false
addSubview(containerStackView)
//leftStackView will be twice as wide as the rightStackView, so
//the distribution is 2/3rds to 1/3rd
leftStackView.widthAnchor.constraint(equalTo:
rightStackView.widthAnchor, multiplier: 2.0).isActive = true