I am trying to display a UILabel that may take up multiple lines but I'm having problem with how the height is resized.
Here is what it looks when I have text over a single line, displaying correctly:
When the text spans multiple lines however this happens:
Here's the interface builder settings I'm using:
Ideally I'd like the text view to remain at athe top of the screen and just take up as much space as it needs to diaplay the text but I really can't tell where I am going wrong.
The text view is a bit tricky to handle with automatic layout. If possible use an UILabel. If not then there are several issues with the text view and the most manageable solution is to add the height constraint which is then manipulated in the code.
The height of the text view content can be determined as:
let height = textView.sizeThatFits(textView.frame.size).height
It is also possible to use
let height = textView.contentSize.height
But the results are sometimes incorrect.
You do need to then set the delegate for the text view so that on change you will refresh the size of the text view.
Well you did give it permission to do so based on your constraints. Any height > 0 as long as it's 20 from the top margin. Since you don't have any other views to base your height off of you can hook up an outlet to your label and use this:
#IBOutlet weak var label: UILabel!
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
label.sizeToFit()
}
Uncheck the "Preferred Width" explicit checkbox(In Size Inspector)
Remove the height constraint on you UILabel.
It will definitely work.
Related
TD;DR
It seems that in some cases systemLayoutSizeFitting does not return the correct height to correctly show / position all subviews of a view. Am I using systemLayoutSizeFitting wrong or is there some other way to avoid this?
Long story:
The XIB file of a UIViewController does not only contain the main view but also a number of other views which are added to the view controllers view at runtime. All these additional views should get the same height when they are added to the view controllers view.
The views might look like this: A simple container view holding some subviews which are stacked on top of each other.
Since the height of the container view should be flexible, the vertical spacing between the bottom button and the lable above it, uses a grater-than constraint.
To give all views the same height, I tried to measure the necessary height of each view using systemLayoutSizeFitting:
#IBOutlet var pageViews: [UIView]!
override func viewDidLoad() {
super.viewDidLoad()
var maxHeight: CGFloat = 0
for pageView in pageViews {
// Add pageView somewhere on view and give it leading, trailing and top
// constraint, but no height constraint yet.
addToView(pageView)
maxHeight = max(maxHeight, pageView.systemLayoutSizeFitting(CGSize(width: view.frame.width, height: UIView.layoutFittingCompressedSize.height), withHorizontalFittingPriority: .required, verticalFittingPriority: .fittingSizeLevel).height)
}
for pageView in pageViews {
// Give all pageViews the same height
pageView.heightAnchor.constraint(equalToConstant: maxHeight).isActive = true
}
}
This does not work, when the label text becomes to long:
In the right example the height is not large enough and thus the button is squeezed. I can counter act this by raising the vertical compression resistance of the button, however in this case the other controls (e.g. the title label) is squeezed...
Why is this? Why does not systemLayoutSizeFitting return a height which is sufficent to show all controls without any squeezing?
Its actually smash button's height when label text is getting bigger . You are setting top and bottom constraints but button height is not declared so when label getting bigger , view basically say "I can reduce button height before updating my height , I have space.Bottom and top constraints are still same , didn't effect."
Giving the constant height constraints of button might be fix your issue.
If you want your view to resist to compression you should use the defaultHigh priority as a verticalFittingPriority instead of fittingSizeLevel.
I have a textview within which is a label. The label gets texts of varying lengths from the server.
Now the texts from the server are displayed like so on my label (which is in a textview)
In order to increase the textview height as per the text in the label, I did this...
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
incidentTextView.translatesAutoresizingMaskIntoConstraints = true
incidentTextView.sizeToFit()
actionTextView.translatesAutoresizingMaskIntoConstraints = true
actionTextView.sizeToFit()
submitByTextView.translatesAutoresizingMaskIntoConstraints = true
submitByTextView.sizeToFit()
}
But this gives me the result as shown below..
How can I align the fields like the first image and yet have the height of the textview increased dynamically as per the text in the label..?
EDIT 1: I cannot see the scrolling option also for UIView..
You could use UILabel instead UITextView and just set numberOfLines = 0.
Make sure you used correct constraints to align UILable proper.
I'm trying to get a rounded UIImageView but it seems to render differently on different devices;
Looks like this on an iPhone Xr:
Looks like this on an iPhone 7:
I have a height constraint of 60 and the following code:
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
self.userAvatar.layer.cornerRadius = self.userAvatar.frame.height / 2
self.userAvatar.layer.masksToBounds = false
self.userAvatar.clipsToBounds = true
self.userAvatar.layer.borderWidth = 0
}
Any ideas?
It seems to me that you have given the image leading and trailing constraints instead of a fixed width.
To achieve a circle give image view width equal to height.
This happens due to different widths of devices.
If you're managing this view using Interface Builder (i.e. Storyboard or XIB), you can enforce a square shape (which becomes a circle when combined with the rounded corners you already have) for the view directly from there by defining a constraint for its Aspect Ratio. No need to code anything.
Control-drag (like you do to create Outlets, Actions, etc.) from the image view to itself, and the following popup will appear.
Select Aspect Ratio, which will create a constraint matching whatever the view's current ratio is (in this example, it's 15:8). If the view was already square, the constraint created should already be correct.
If not, you can find that constraint by clicking the following icon (for the Size inspector):
From there, you can double-click on that constraint to edit it, and change the Multiplier to 1:1:
In fact, an even easier option is, once you've Control-dragged from the view to itself, hold down Alt/Opt and the option displayed in the popup will change to Aspect Ratio (1:1), meaning you can set it directly from there without even having to edit the constraint.
Constrain the height equal to the width.
And, create a simple UIImageView subclass:
class RoundedImageView: UIImageView {
override func layoutSubviews() {
super.layoutSubviews()
layer.cornerRadius = bounds.height / 2
}
}
The frame can (and will) change based on view lifecycle. By updating the cornerRadius in layoutSubviews() it will keep it "round".
I am going through the Stanford Winter 2015 Swift/iOS course and while doing the assignments I run into a behavior I'd like to change.
I use Autolayout as described in the videos (making the display pin to leading and trailing view edges) and the Calculator app "Display" UILabel is fine with an initial value of 0 and whenever the value used to set it (a String) is non-nil and non "".
If it is either nil or "", the entire UILabel disappears. What I am trying to do is to "clear" the display whenever there is no value to display or an incorrect calculation resulted in nil.
Any tips on who to deal with this in general? "Clearing" a UILabel without changing it's on-screen dimensions?
Edit (thanks Rob)
The UILabel has the following constraints
1. Option-click drag-left to containing UIView, selected "leading" something (on commute to work can't check yet for exact wording.
2. Same method as (1) except that the drag is to the right edge and selecting "trailing"
3. Option click-drag up to top of view, select "vertical" menu option.
4. Same as (3) except that drag is to a UIButton underneath the UILabel on the GUI.
With those settings, the label when it contains a number is always visible and (if understand, will color it to verify) stretches across the screen even if the text doesn't.
The layout looks correct in profile and landscape as long as content of UILabel is not empty. If empty, it seems to "shrink to fit" so much that the buttons below get moved up towards the top.
I'm a C++ dev since mid 90s but I have little UI experience and no more than a couple weeks experience in iOS/Swift development.
Thanks!
You can always give the UILabel a min width and min height or constraints that holds the left and right side of the label. That should keep the label from changing it's dimensions to zero.
Use a custom UILabel class assigned in Interface Builder >> Identity inspector >> Custom Class >> Class to override UILabel intrinsic content size.
No need to create any superfluous auto-layout constraints.
Swift:
class UILabelNonCompressible: UILabel
{
private static let NonCompressibleInvisibleContent = " "
override var intrinsicContentSize: CGSize
{
if /* zero-width */ text == nil ? true : text!.isEmpty
{
// prefer mirror-and-calculate over modify-calculate-restore due to KVO
let doppelganger = createCopy()
// calculate for any non-zero -height content
doppelganger.text = UILabelNonCompressible.NonCompressibleInvisibleContent
// override
return doppelganger.intrinsicContentSize
}
else
{
return super.intrinsicContentSize
}
}
}
You will also need "How do copy for UILabel?":
extension UILabel
{
func createCopy() -> UILabel
{
let archivedData = NSKeyedArchiver.archivedData(withRootObject: self)
return NSKeyedUnarchiver.unarchiveObject(with: archivedData) as! UILabel
}
}
Suppose I have three labels that are laid out below each other in a column. The uppermost label's top edge is pinned to the superview's top edge. All following labels' top edges are pinned to the preceding label's bottom edge. The leading and trailing edges of all labels are pinned to the leading and trailing edge of the superview. Here's what it looks like in Interface Builder (I added a blue background on every label to visualize its extent).
In the simulator the result looks like this.
All labels are connected to outlets in a view controller.
#IBOutlet weak var label1: UILabel!
#IBOutlet weak var label2: UILabel!
#IBOutlet weak var label3: UILabel!
When I set the text of label2 to nil
label2.text = nil
the label itself collapses.
However, the top and bottom spaces around the label do not collapse. This is evident by the fact that there is no blue background on the middle label in the last screenshot. As a result, the space between label1 and label3 is double the space of the layout in the first screenshot.
My question is - on iOS8 - what is the easiest way to collapse either the middle label's top or bottom space so that the two remaining labels still use the vertical spacing defined in the original layout? To be clear, this is the result I want to achieve.
Options I've found so far:
Bottom/Top Spacing Constraint Outlet
Define an outlet for the middle label's top or bottom spacing constraint.
#IBOutlet weak var spacingConstraint: NSLayoutConstraint!
Store the constraint's initial constant into a variable (e.g. in awakeFromNib or viewDidLoad).
private var initialSpacing: CGFloat!
override func viewDidLoad() {
initialSpacing = spacingConstraint.constant
...
Set the constraint's constant to zero whenever the text is set to nil or back to its initial value when the text is not nil.
spacingConstraint.constant = label2.text == nil ? 0 : initialSpacing
This approach feels a bit clumsy since it requires two additional variables.
Height Constraint Outlet
Set the vertical spacing around the middle label to zero and increase its height by the same amount. Define an outlet for the height constraint and proceed as above, setting the height to zero when the text is nil and back to it's initial value when the height is not nil.
This is still as clumsy as the previous approach. In addition, you have to hardcode the spacing and cannot use the built-in default spacings (blank fields in Interface builder).
UIStackView
This is not an option since UIStackView is only available on iOS 9 and above.
I'm using this UIView category for this purpose.
It extends UIView by adding two more property named fd_collapsed and fd_collapsibleConstraints using objective-c runtime framework. You simply drag constraints that you want to be disabled when fd_collapsed property set to YES. Behind the scene, it captures the initial value of these constraints, then set to zero whenever fd_collapsed is YES. Reset to initial values when fd_collapsed is NO.
There is also another property called fd_autocollapsed
Not every view needs to add a width or height constraint, views like UILabel, UIImageView have their Intrinsic content size when they have content in it. For these views, we provide a Auto collapse property, when its content is gone, selected constraints will collapse automatically.
This property automatically sets fd_collapsed property to YES whenever specified view has content to display.
It's really simple to use. It's kinda shame that there is no builtin solution like that.
Your solutions are good enough for me and I'd do Bottom/Top Spacing Constraint Outlet solution but since you want something different. You can use this third party: https://github.com/orta/ORStackView It has iOS7+ support and do exactly what you need.
This is low-key a pain all perfectionist devs learn about when trying to stack a bunch of labels. Solutions can get too verbose, annoying to folow, and really annoying to implement (ie. keeping a reference to the top constraint... gets annoying once you do it multiple times, or just change the order of the labels)
Hopefully my code below puts an end to this:
class MyLabel: UILabel {
var topPadding: CGFloat = 0
override func drawText(in rect: CGRect) {
var newRect = rect
newRect.origin.y += topPadding/2
super.drawText(in: newRect)
}
override var intrinsicContentSize: CGSize {
var newIntrisicSize = super.intrinsicContentSize
guard newIntrisicSize != .zero else {
return .zero
}
newIntrisicSize.height += topPadding
return newIntrisicSize
}
}
Usage:
let label = MyLabel()
label.topPadding = 10
// then use autolayout to stack your labels with 0 offset
Granted, its only for top padding, but that should be the only thing you need to layout your labels properly. It works great with or without autolayout. Also its a big plus not needing to do any extra mental gymnastics just to do something so simple. Enjoy!