[英]Why do embedded UIStackView's, filled Proportionally, with spacing and Layout Margins causes constraint errors and how to fix?
This question comes off the back of the great question and answer at:这个问题来自伟大问答的背后:
Stackoverflow: Why does a UIStackView with a single view, fill Proportionally, and Layout Margins causes ambiguous constraint error? Stackoverflow:为什么单视图的UIStackView,按比例填充,和Layout Margins会导致模糊约束错误?
I am having similar issues but with embedded stackviews inside a scrollview.我有类似的问题,但在滚动视图中嵌入了堆栈视图。 I have modified the explanation code from the above question.
我已经修改了上述问题的解释代码。 In my working code, I have a parentVC that loads into a container view, a childVC that has the embedded scrollView and stackViews (outer stackview is vertical and then each of its subviews are a bunch of horizontal stackviews).
在我的工作代码中,我有一个加载到容器视图中的 parentVC,一个具有嵌入式 scrollView 和 stackViews 的 childVC(外部 stackview 是垂直的,然后它的每个子视图都是一堆水平的 stackviews)。 There are a range of options from fixed width label, icons and expanding labels.
有一系列选项,包括固定宽度 label、图标和扩展标签。
The problem is I either get UISV-spacing constraint errors or trailing errors for the expanding labels.问题是我得到 UISV 间距约束错误或扩展标签的尾随错误。 I understand from the above question that this has to do with the sequence of how the auto layout engine is calculating the proportional widths, spacing etc. but have no idea how to fix.
我从上述问题中了解到,这与自动布局引擎如何计算比例宽度、间距等的顺序有关,但不知道如何解决。 Any suggestions would be welcome.
欢迎大家提出意见。 I'm attaching the code I'm using:
我附上了我正在使用的代码:
class ParentVC: UIViewController {
override func viewDidLoad() {
let vcContainer = UIView()
view.addSubview(vcContainer)
vcContainer.backgroundColor = .systemYellow
vcContainer.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
vcContainer.topAnchor.constraint(equalTo: view.topAnchor, constant: 100),
vcContainer.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -150),
vcContainer.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 50),
vcContainer.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -50),
])
let vc = ChildVC()
addChild(vc)
vc.didMove(toParent: self)
vcContainer.addSubview(vc.view)
vc.view.frame = vcContainer.bounds
vc.view.heightAnchor.constraint(equalTo: vcContainer.heightAnchor).isActive = true
}
}
class ChildVC: UIViewController {
let outerStackView: UIStackView = {
let v = UIStackView()
v.translatesAutoresizingMaskIntoConstraints = false
v.axis = .vertical
v.spacing = 8
return v
}()
let scrollView: UIScrollView = {
let sv = UIScrollView()
sv.translatesAutoresizingMaskIntoConstraints = false
return sv
}()
override func viewDidLoad() {
super.viewDidLoad()
for _ in 1...7 {
let lbl = UILabel()
lbl.font = UIFont.systemFont(ofSize: 12.0, weight: .light)
lbl.numberOfLines = 0
lbl.textAlignment = .center
outerStackView.addArrangedSubview(lbl)
let sv = UIStackView()
sv.translatesAutoresizingMaskIntoConstraints = false
sv.axis = .horizontal
sv.distribution = .fillProportionally
sv.spacing = 10
outerStackView.addArrangedSubview(sv)
}
view.addSubview(scrollView)
scrollView.addSubview(outerStackView)
NSLayoutConstraint.activate([
scrollView.topAnchor.constraint(equalTo: view.topAnchor),
scrollView.widthAnchor.constraint(equalTo: view.widthAnchor),
scrollView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
scrollView.heightAnchor.constraint(equalTo: view.heightAnchor),
outerStackView.topAnchor.constraint(equalTo: scrollView.contentLayoutGuide.topAnchor),
outerStackView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
outerStackView.leadingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.leadingAnchor),
outerStackView.trailingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.trailingAnchor),
outerStackView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
])
// StackView 1
if let lbl = outerStackView.arrangedSubviews[0] as? UILabel,
let sv = outerStackView.arrangedSubviews[1] as? UIStackView {
let v = ExpandingLabel()
sv.addArrangedSubview(v)
lbl.text = "SV1: One view \n no layoutMargins"
}
// StackView 2
if let lbl = outerStackView.arrangedSubviews[2] as? UILabel,
let sv = outerStackView.arrangedSubviews[3] as? UIStackView {
let v = FixedLabel()
sv.addArrangedSubview(v)
let v2 = ExpandingLabel()
sv.addArrangedSubview(v2)
lbl.text = "SV2: Two views \n no layoutMargins"
}
// comment out this block to see the auto-layout error goes away
// StackView 3
if let lbl = outerStackView.arrangedSubviews[4] as? UILabel,
let sv = outerStackView.arrangedSubviews[5] as? UIStackView {
let v = ExpandingLabel()
sv.addArrangedSubview(v)
sv.isLayoutMarginsRelativeArrangement = true
sv.layoutMargins = .init(top: 0, left: 10, bottom: 0, right: 11)
lbl.text = "SV3: One view\nlayoutMargins left: \(sv.layoutMargins.left), right: \(sv.layoutMargins.right)"
}
// StackView 4
if let lbl = outerStackView.arrangedSubviews[6] as? UILabel,
let sv = outerStackView.arrangedSubviews[7] as? UIStackView {
let v = FixedLabel()
sv.addArrangedSubview(v)
let v2 = ExpandingLabel()
sv.addArrangedSubview(v2)
sv.isLayoutMarginsRelativeArrangement = true
sv.layoutMargins = .init(top: 0, left: 12, bottom: 0, right: 13)
lbl.text = "SV4: Two views\nlayoutMargins\n left: \(sv.layoutMargins.left), right: \(sv.layoutMargins.right)"
}
// StackView 5
if let lbl = outerStackView.arrangedSubviews[8] as? UILabel,
let sv = outerStackView.arrangedSubviews[9] as? UIStackView {
let v = FixedLabel()
sv.addArrangedSubview(v)
let v2 = ExpandingLabel()
sv.addArrangedSubview(v2)
sv.isLayoutMarginsRelativeArrangement = true
sv.layoutMargins = .init(top: 0, left: 101, bottom: 0, right: 0)
lbl.text = "SV5: Two views \nlayoutMargins left: \(sv.layoutMargins.left), right: \(sv.layoutMargins.right)"
}
// StackView 6
if let lbl = outerStackView.arrangedSubviews[10] as? UILabel,
let sv = outerStackView.arrangedSubviews[11] as? UIStackView {
let v = IconView()
sv.addArrangedSubview(v)
let v2 = ExpandingLabel()
v2.numberOfLines = 0
sv.addArrangedSubview(v2)
sv.isLayoutMarginsRelativeArrangement = true
sv.layoutMargins = .init(top: 0, left: 14, bottom: 0, right: 15)
lbl.text = "SV6: Two views\nlayoutMargins left: \(sv.layoutMargins.left), right: \(sv.layoutMargins.right)"
}
// StackView 7
if let lbl = outerStackView.arrangedSubviews[12] as? UILabel,
let sv = outerStackView.arrangedSubviews[13] as? UIStackView {
let v = ExpandingLabel()
sv.addArrangedSubview(v)
sv.isLayoutMarginsRelativeArrangement = true
sv.layoutMargins = .init(top: 0, left: 16, bottom: 0, right: 17)
let v2 = ExpandingLabel()
sv.addArrangedSubview(v2)
lbl.text = "SV7: One view\nlayoutMargins left: \(sv.layoutMargins.left), right: \(sv.layoutMargins.right)"
}
}
}
class IconView: UIImageView {
init() {
super.init(frame: .zero)
self.backgroundColor = UIColor.systemRed
self.tintColor = .white
image = UIImage(systemName: "square.and.arrow.up")?.applyingSymbolConfiguration(UIImage.SymbolConfiguration(textStyle: .body))
contentMode = .center
translatesAutoresizingMaskIntoConstraints = false
adjustsImageSizeForAccessibilityContentSizeCategory = true
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class FixedLabel : UILabel {
override init(frame: CGRect) {
super.init(frame: frame)
text = "fxd"
backgroundColor = .systemRed
translatesAutoresizingMaskIntoConstraints = false
setContentCompressionResistancePriority(.required, for: .horizontal)
setContentHuggingPriority(.required, for: .horizontal)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class ExpandingLabel: UILabel {
override init(frame: CGRect) {
super.init(frame: frame)
text = "expanding label"
backgroundColor = .systemGreen
numberOfLines = 3
font = UIFont.preferredFont(forTextStyle: .body)
adjustsFontForContentSizeCategory = true
translatesAutoresizingMaskIntoConstraints = false
setContentHuggingPriority(.defaultLow, for: .horizontal)
setContentCompressionResistancePriority(.defaultHigh, for: .vertical)
setContentCompressionResistancePriority(.defaultHigh, for: .horizontal)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
The above produces the desired result as per below:上述产生的预期结果如下:
The log errors are:日志错误是:
2021-03-16 10:01:22.815997+1100 stackviewsWithProportionalFill[8528:4745644] Sherlock initialised 2021-03-16 10:01:23.051125+1100 stackviewsWithProportionalFill[8528:4745644] [LayoutConstraints] Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (
"<NSLayoutConstraint:0x600003317e80 'UISV-canvas-connection' UIStackView:0x7feb0270f930.leading == stackviewsWithProportionalFill.FixedLabel:0x7feb02715f80.leading (active)>",
"<NSLayoutConstraint:0x600003317930 'UISV-canvas-connection' H:[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0270b710]-(0)-| (active, names: '|':UIStackView:0x7feb0270f930 )>",
"<NSLayoutConstraint:0x6000033172a0 'UISV-fill-proportionally' stackviewsWithProportionalFill.ExpandingLabel:0x7feb0270b710.width == UIStackView:0x7feb0270f930.width (active)>",
"<NSLayoutConstraint:0x6000033178e0 'UISV-spacing' H:[stackviewsWithProportionalFill.FixedLabel:0x7feb02715f80]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0270b710] (active)>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x6000033178e0 'UISV-spacing' H:[stackviewsWithProportionalFill.FixedLabel:0x7feb02715f80]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0270b710] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. 2021-03-16 10:01:23.057974+1100 stackviewsWithProportionalFill[8528:4745644] [LayoutConstraints] Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (
"<NSLayoutConstraint:0x60000332cb40 UIScrollView:0x7feb0381ea00.width == UIView:0x7feb0270aeb0.width (active)>",
"<NSLayoutConstraint:0x60000332d270 UIStackView:0x7feb02709160.width == UIScrollView:0x7feb0381ea00.width (active)>",
"<NSLayoutConstraint:0x600003370fa0 'UISV-alignment' UILabel:0x7feb0270b2a0.leading == UIStackView:0x7feb02711930.leading (active)>",
"<NSLayoutConstraint:0x6000033713b0 'UISV-alignment' UILabel:0x7feb0270b2a0.trailing == UIStackView:0x7feb02711930.trailing (active)>",
"<NSLayoutConstraint:0x600003310eb0 'UISV-canvas-connection' UILayoutGuide:0x6000029208c0'UIViewLayoutMarginsGuide'.leading == stackviewsWithProportionalFill.FixedLabel:0x7feb02717140.leading (active)>",
"<NSLayoutConstraint:0x6000033123f0 'UISV-canvas-connection' UILayoutGuide:0x6000029208c0'UIViewLayoutMarginsGuide'.trailing == stackviewsWithProportionalFill.ExpandingLabel:0x7feb02717530.trailing (active)>",
"<NSLayoutConstraint:0x600003370c80 'UISV-canvas-connection' UIStackView:0x7feb02709160.leading == UILabel:0x7feb0270b2a0.leading (active)>",
"<NSLayoutConstraint:0x600003370cd0 'UISV-canvas-connection' H:[UILabel:0x7feb0270b2a0]-(0)-| (active, names: '|':UIStackView:0x7feb02709160 )>",
"<NSLayoutConstraint:0x600003312530 'UISV-spacing' H:[stackviewsWithProportionalFill.FixedLabel:0x7feb02717140]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb02717530] (active)>",
"<NSLayoutConstraint:0x600003371540 'UIView-Encapsulated-Layout-Width' UIView:0x7feb0270aeb0.width == 0 (active)>",
"<NSLayoutConstraint:0x600003312300 'UIView-leftMargin-guide-constraint' H:|-(101)-[UILayoutGuide:0x6000029208c0'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':UIStackView:0x7feb02711930 )>",
"<NSLayoutConstraint:0x6000033123a0 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x6000029208c0'UIViewLayoutMarginsGuide']-(0)-|(LTR) (active, names: '|':UIStackView:0x7feb02711930 )>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600003312530 'UISV-spacing' H:[stackviewsWithProportionalFill.FixedLabel:0x7feb02717140]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb02717530] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. 2021-03-16 10:01:23.065566+1100 stackviewsWithProportionalFill[8528:4745644] [LayoutConstraints] Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (
"<NSLayoutConstraint:0x60000332cb40 UIScrollView:0x7feb0381ea00.width == UIView:0x7feb0270aeb0.width (active)>",
"<NSLayoutConstraint:0x60000332d270 UIStackView:0x7feb02709160.width == UIScrollView:0x7feb0381ea00.width (active)>",
"<NSLayoutConstraint:0x6000033710e0 'UISV-alignment' UILabel:0x7feb0270b2a0.leading == UIStackView:0x7feb02712730.leading (active)>",
"<NSLayoutConstraint:0x6000033714f0 'UISV-alignment' UILabel:0x7feb0270b2a0.trailing == UIStackView:0x7feb02712730.trailing (active)>",
"<NSLayoutConstraint:0x6000033138e0 'UISV-canvas-connection' UILayoutGuide:0x600002920a80'UIViewLayoutMarginsGuide'.leading == stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260e660.leading (active)>",
"<NSLayoutConstraint:0x600003313930 'UISV-canvas-connection' UILayoutGuide:0x600002920a80'UIViewLayoutMarginsGuide'.trailing == stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260ecd0.trailing (active)>",
"<NSLayoutConstraint:0x600003370c80 'UISV-canvas-connection' UIStackView:0x7feb02709160.leading == UILabel:0x7feb0270b2a0.leading (active)>",
"<NSLayoutConstraint:0x600003370cd0 'UISV-canvas-connection' H:[UILabel:0x7feb0270b2a0]-(0)-| (active, names: '|':UIStackView:0x7feb02709160 )>",
"<NSLayoutConstraint:0x600003370050 'UISV-spacing' H:[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260e660]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260ecd0] (active)>",
"<NSLayoutConstraint:0x600003371540 'UIView-Encapsulated-Layout-Width' UIView:0x7feb0270aeb0.width == 0 (active)>",
"<NSLayoutConstraint:0x6000033137f0 'UIView-leftMargin-guide-constraint' H:|-(16)-[UILayoutGuide:0x600002920a80'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':UIStackView:0x7feb02712730 )>",
"<NSLayoutConstraint:0x600003313890 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x600002920a80'UIViewLayoutMarginsGuide']-(17)-|(LTR) (active, names: '|':UIStackView:0x7feb02712730 )>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600003370050 'UISV-spacing' H:[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260e660]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260ecd0] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. 2021-03-16 10:01:23.066504+1100 stackviewsWithProportionalFill[8528:4745644] [LayoutConstraints] Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (
"<NSLayoutConstraint:0x60000332cb40 UIScrollView:0x7feb0381ea00.width == UIView:0x7feb0270aeb0.width (active)>",
"<NSLayoutConstraint:0x60000332d270 UIStackView:0x7feb02709160.width == UIScrollView:0x7feb0381ea00.width (active)>",
"<NSLayoutConstraint:0x600003371040 'UISV-alignment' UILabel:0x7feb0270b2a0.leading == UIStackView:0x7feb02712130.leading (active)>",
"<NSLayoutConstraint:0x600003371450 'UISV-alignment' UILabel:0x7feb0270b2a0.trailing == UIStackView:0x7feb02712130.trailing (active)>",
"<NSLayoutConstraint:0x600003312e90 'UISV-canvas-connection' UILayoutGuide:0x600002920b60'UIViewLayoutMarginsGuide'.leading == stackviewsWithProportionalFill.IconView:0x7feb027179a0.leading (active)>",
"<NSLayoutConstraint:0x600003312ee0 'UISV-canvas-connection' UILayoutGuide:0x600002920b60'UIViewLayoutMarginsGuide'.trailing == stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260e1f0.trailing (active)>",
"<NSLayoutConstraint:0x600003370c80 'UISV-canvas-connection' UIStackView:0x7feb02709160.leading == UILabel:0x7feb0270b2a0.leading (active)>",
"<NSLayoutConstraint:0x600003370cd0 'UISV-canvas-connection' H:[UILabel:0x7feb0270b2a0]-(0)-| (active, names: '|':UIStackView:0x7feb02709160 )>",
"<NSLayoutConstraint:0x600003313020 'UISV-spacing' H:[stackviewsWithProportionalFill.IconView:0x7feb027179a0]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260e1f0] (active)>",
"<NSLayoutConstraint:0x600003371540 'UIView-Encapsulated-Layout-Width' UIView:0x7feb0270aeb0.width == 0 (active)>",
"<NSLayoutConstraint:0x600003312da0 'UIView-leftMargin-guide-constraint' H:|-(14)-[UILayoutGuide:0x600002920b60'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':UIStackView:0x7feb02712130 )>",
"<NSLayoutConstraint:0x600003312e40 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x600002920b60'UIViewLayoutMarginsGuide']-(15)-|(LTR) (active, names: '|':UIStackView:0x7feb02712130 )>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600003313020 'UISV-spacing' H:[stackviewsWithProportionalFill.IconView:0x7feb027179a0]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb0260e1f0] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. 2021-03-16 10:01:23.067723+1100 stackviewsWithProportionalFill[8528:4745644] [LayoutConstraints] Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (
"<NSLayoutConstraint:0x60000332cb40 UIScrollView:0x7feb0381ea00.width == UIView:0x7feb0270aeb0.width (active)>",
"<NSLayoutConstraint:0x60000332d270 UIStackView:0x7feb02709160.width == UIScrollView:0x7feb0381ea00.width (active)>",
"<NSLayoutConstraint:0x600003370f00 'UISV-alignment' UILabel:0x7feb0270b2a0.leading == UIStackView:0x7feb02710b30.leading (active)>",
"<NSLayoutConstraint:0x600003371310 'UISV-alignment' UILabel:0x7feb0270b2a0.trailing == UIStackView:0x7feb02710b30.trailing (active)>",
"<NSLayoutConstraint:0x6000033118b0 'UISV-canvas-connection' UILayoutGuide:0x600002920380'UIViewLayoutMarginsGuide'.leading == stackviewsWithProportionalFill.FixedLabel:0x7feb02716a60.leading (active)>",
"<NSLayoutConstraint:0x600003311900 'UISV-canvas-connection' UILayoutGuide:0x600002920380'UIViewLayoutMarginsGuide'.trailing == stackviewsWithProportionalFill.ExpandingLabel:0x7feb02716cd0.trailing (active)>",
"<NSLayoutConstraint:0x600003370c80 'UISV-canvas-connection' UIStackView:0x7feb02709160.leading == UILabel:0x7feb0270b2a0.leading (active)>",
"<NSLayoutConstraint:0x600003370cd0 'UISV-canvas-connection' H:[UILabel:0x7feb0270b2a0]-(0)-| (active, names: '|':UIStackView:0x7feb02709160 )>",
"<NSLayoutConstraint:0x600003311a40 'UISV-spacing' H:[stackviewsWithProportionalFill.FixedLabel:0x7feb02716a60]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb02716cd0] (active)>",
"<NSLayoutConstraint:0x600003371540 'UIView-Encapsulated-Layout-Width' UIView:0x7feb0270aeb0.width == 0 (active)>",
"<NSLayoutConstraint:0x6000033117c0 'UIView-leftMargin-guide-constraint' H:|-(12)-[UILayoutGuide:0x600002920380'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':UIStackView:0x7feb02710b30 )>",
"<NSLayoutConstraint:0x600003311860 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x600002920380'UIViewLayoutMarginsGuide']-(13)-|(LTR) (active, names: '|':UIStackView:0x7feb02710b30 )>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600003311a40 'UISV-spacing' H:[stackviewsWithProportionalFill.FixedLabel:0x7feb02716a60]-(10)-[stackviewsWithProportionalFill.ExpandingLabel:0x7feb02716cd0] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. 2021-03-16 10:01:23.068649+1100 stackviewsWithProportionalFill[8528:4745644] [LayoutConstraints] Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (
"<NSLayoutConstraint:0x60000332cb40 UIScrollView:0x7feb0381ea00.width == UIView:0x7feb0270aeb0.width (active)>",
"<NSLayoutConstraint:0x60000332d270 UIStackView:0x7feb02709160.width == UIScrollView:0x7feb0381ea00.width (active)>",
"<NSLayoutConstraint:0x600003370e60 'UISV-alignment' UILabel:0x7feb0270b2a0.leading == UIStackView:0x7feb02710130.leading (active)>",
"<NSLayoutConstraint:0x600003371270 'UISV-alignment' UILabel:0x7feb0270b2a0.trailing == UIStackView:0x7feb02710130.trailing (active)>",
"<NSLayoutConstraint:0x600003316df0 'UISV-canvas-connection' UILayoutGuide:0x600002939880'UIViewLayoutMarginsGuide'.leading == stackviewsWithProportionalFill.ExpandingLabel:0x7feb027167f0.leading (active)>",
"<NSLayoutConstraint:0x600003316da0 'UISV-canvas-connection' UILayoutGuide:0x600002939880'UIViewLayoutMarginsGuide'.trailing == stackviewsWithProportionalFill.ExpandingLabel:0x7feb027167f0.trailing (active)>",
"<NSLayoutConstraint:0x600003370c80 'UISV-canvas-connection' UIStackView:0x7feb02709160.leading == UILabel:0x7feb0270b2a0.leading (active)>",
"<NSLayoutConstraint:0x600003370cd0 'UISV-canvas-connection' H:[UILabel:0x7feb0270b2a0]-(0)-| (active, names: '|':UIStackView:0x7feb02709160 )>",
"<NSLayoutConstraint:0x600003371540 'UIView-Encapsulated-Layout-Width' UIView:0x7feb0270aeb0.width == 0 (active)>",
"<NSLayoutConstraint:0x600003316ee0 'UIView-leftMargin-guide-constraint' H:|-(10)-[UILayoutGuide:0x600002939880'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':UIStackView:0x7feb02710130 )>",
"<NSLayoutConstraint:0x600003316e40 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x600002939880'UIViewLayoutMarginsGuide']-(11)-|(LTR) (active, names: '|':UIStackView:0x7feb02710130 )>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600003316da0 'UISV-canvas-connection' UILayoutGuide:0x600002939880'UIViewLayoutMarginsGuide'.trailing == stackviewsWithProportionalFill.ExpandingLabel:0x7feb027167f0.trailing (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. 2021-03-16 10:01:24.091972+1100 stackviewsWithProportionalFill[8528:4745811] [] nw_protocol_get_quic_image_block_invoke dlopen libquic failed
You have inadvertently presented one of the (many) reasons I tell people to *forget you ever heard of the .fillProportionally
Distribution property of a UIStackView
...您无意中提出了我告诉人们*忘记您听说过
UIStackView
的.fillProportionally
Distribution 属性的(许多)原因之一...
For your horizontal stack views, you have:对于您的水平堆栈视图,您有:
sv.distribution = .fillProportionally
So you just told auto-layout: "Stretch the widths of the arranged subviews proportionally to each other!"所以你只是告诉自动布局: “按比例拉伸排列的子视图的宽度!”
You then add a label as an arranged subview, and you set this property on the label:然后添加 label 作为排列的子视图,并在 label 上设置此属性:
setContentHuggingPriority(.required, for: .horizontal)
So you just told auto-layout: "Do NOT stretch the width of this label!"所以你只是告诉自动布局: “不要拉伸这个标签的宽度!”
Kinda tough for auto-layout to both stretch and not stretch the view at the same time:)自动布局很难同时拉伸和不拉伸视图:)
Unless you know exactly why you want .fillProportionally
(and in this case, that is not what you want), don't use it.除非您确切知道为什么要
.fillProportionally
(在这种情况下,这不是您想要的),否则不要使用它。 For your layout, you want the default .fill
.对于您的布局,您需要默认的
.fill
。
So, if we forget for a moment that you are loading ChildVC
as a, well, child VC ( grin ) and set ChildVC
as the "root" view controller, and leave sv.distribution =.fillProportionally
, you'll get layout errors.因此,如果我们暂时忘记了您将
ChildVC
作为子 VC ( grin ) 加载并将ChildVC
设置为“根”视图 controller 并离开sv.distribution =.fillProportionally
,您将收到布局错误。
If you change that to sv.distribution =.fill
, you won't get layout errors.如果将其更改为
sv.distribution =.fill
,则不会出现布局错误。
But, back to using that VC as a child ... even with .fill
you'll still get layout errors.但是,回到使用那个 VC 作为一个孩子......即使使用
.fill
你仍然会得到布局错误。 So...所以...
Change your "load the child" code in ParentVC
to this:将
ParentVC
中的“加载孩子”代码更改为:
class ParentVC: UIViewController {
override func viewDidLoad() {
let vcContainer = UIView()
view.addSubview(vcContainer)
vcContainer.backgroundColor = .systemYellow
vcContainer.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
vcContainer.topAnchor.constraint(equalTo: view.topAnchor, constant: 100),
vcContainer.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -150),
vcContainer.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 50),
vcContainer.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -50),
])
let vc = ChildVC()
addChild(vc)
vcContainer.addSubview(vc.view)
vc.view.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
vc.view.topAnchor.constraint(equalTo: vcContainer.topAnchor),
vc.view.leadingAnchor.constraint(equalTo: vcContainer.leadingAnchor),
vc.view.trailingAnchor.constraint(equalTo: vcContainer.trailingAnchor),
vc.view.bottomAnchor.constraint(equalTo: vcContainer.bottomAnchor),
])
vc.didMove(toParent: self)
}
}
That approach, combined with sv.distribution =.fill
, gets rid of the errors.这种方法与
sv.distribution =.fill
结合使用,可以消除错误。
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