UIView is behind translucent navigation bar with pragmatically created view constraints - ios

Question

I have a function that inserts a generic UIView into a view controller at the top of the view and I would like for the inserted view to be at the bottom of a navigation bar, or if there isn't one, at the bottom of the status bar.
I assumed that the view controllers top layout guide would update automatically when it's embedded in a navigation controller, but that doesn't seem to be the case.
Here's what I have so far:
init(in viewController: UIViewController) {
super.init(frame: CGRect(x: 0, y: 0,
width: viewController.view.frame.size.width, height: 50))
initializeSubviews()
viewController.view.addSubview(self)
self.topAnchor.constraint(equalTo: viewController.topLayoutGuide.bottomAnchor, constant: 0).isActive = true
self.leadingAnchor.constraint(equalTo: viewController.view.leadingAnchor, constant: 0).isActive = true
viewController.view.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: 0).isActive = true
self.addConstraint(NSLayoutConstraint(item: self, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 50))
self.setNeedsLayout()
}
I can achieve this in the interface builder using a placeholder view, so I tried to use the same constraint anchors as the ones used here:
The problem is that the view is always at Y position 0 and is behind the navigation bar. I cannot change the translucency setting of the navigation bar.
I get the following errors in the console when the view is loaded:
<MyApp.MyReusableView: 0x101f3b590; frame = (0 0; 0 0); layer = <CALayer: 0x17003e720>>
2017-01-09 17:07:21.347965 MyApp[2483:984880] [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.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x1742862c0 h=--& v=--& MyApp.MyReusableView:0x101f3b590.width == 0 (active)>",
"<NSLayoutConstraint:0x1702882f0 H:|-(0)-[MyApp.MyReusableView:0x101f3b590] (active, names: '|':UIView:0x101f29f00 )>",
"<NSLayoutConstraint:0x170288340 H:[MyApp.MyReusableView:0x101f3b590]-(0)-| (active, names: '|':UIView:0x101f29f00 )>",
"<NSLayoutConstraint:0x174286450 'UIView-Encapsulated-Layout-Width' UIView:0x101f29f00.width == 375 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x170288340 H:[MyApp.MyReusableView:0x101f3b590]-(0)-| (active, names: '|':UIView:0x101f29f00 )>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2017-01-09 17:07:21.350923 MyApp[2483:984880] [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.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x174280a50 h=-&- v=-&- UIView:0x102b38f70.width == MyApp.MyReusableView:0x101f3b590.width (active)>",
"<NSAutoresizingMaskLayoutConstraint:0x1742862c0 h=--& v=--& MyApp.MyReusableView:0x101f3b590.width == 0 (active)>",
"<NSLayoutConstraint:0x174286090 H:|-(16)-[UILabel:0x102b23d20'\Uf170'] (active, names: '|':UIControl:0x102b22d10 )>",
"<NSLayoutConstraint:0x174285ff0 H:[UILabel:0x102b23d20'\Uf170']-(8)-[UILabel:0x102b2efa0'Test Notification'] (active)>",
"<NSLayoutConstraint:0x174285f50 H:[UILabel:0x102b2efa0'Test Notification']-(0)-| (active, names: '|':UIControl:0x102b22d10 )>",
"<NSLayoutConstraint:0x174285cd0 H:|-(0)-[UIControl:0x102b22d10] (active, names: '|':UIView:0x102b38f70 )>",
"<NSLayoutConstraint:0x174285870 H:[UIButton:0x102b0d040'\Uf05e']-(0)-| (active, names: '|':UIView:0x102b38f70 )>",
"<NSLayoutConstraint:0x1742857d0 H:[UIControl:0x102b22d10]-(0)-[UIButton:0x102b0d040'\Uf05e'] (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x174285ff0 H:[UILabel:0x102b23d20'']-(8)-[UILabel:0x102b2efa0'Test Notification'] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2017-01-09 17:07:21.352456 MyApp[2483:984880] [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.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x174286360 h=--& v=--& MyApp.MyReusableView:0x101f3b590.height == 0 (active)>",
"<NSLayoutConstraint:0x170288390 MyApp.MyReusableView:0x101f3b590.height == 50 (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x170288390 MyApp.MyReusableView:0x101f3b590.height == 50 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2017-01-09 17:07:21.354622 MyApp[2483:984880] [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.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<_UILayoutSupportConstraint:0x1702877b0 _UILayoutGuide:0x101f3ae30.height == 64 (active)>",
"<_UILayoutSupportConstraint:0x17009d420 V:|-(0)-[_UILayoutGuide:0x101f3ae30] (active, names: '|':UIView:0x101f29f00 )>",
"<NSAutoresizingMaskLayoutConstraint:0x174286270 h=--& v=--& MyApp.MyReusableView:0x101f3b590.midY == 0 (active)>",
"<NSAutoresizingMaskLayoutConstraint:0x174286360 h=--& v=--& MyApp.MyReusableView:0x101f3b590.height == 0 (active)>",
"<NSLayoutConstraint:0x170287f30 V:[_UILayoutGuide:0x101f3ae30]-(0)-[MyApp.MyReusableView:0x101f3b590] (active)>",
"<NSAutoresizingMaskLayoutConstraint:0x174286540 h=-&- v=-&- 'UIView-Encapsulated-Layout-Top' UIView:0x101f29f00.minY == 0 (active, names: '|':UIViewControllerWrapperView:0x102b09100 )>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x170287f30 V:[_UILayoutGuide:0x101f3ae30]-(0)-[MyApp.MyReusableView:0x101f3b590] (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2017-01-09 17:07:21.356571 MyApp[2483:984880] [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.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x174280a50 h=-&- v=-&- UIView:0x102b38f70.width == MyApp.MyReusableView:0x101f3b590.width (active)>",
"<NSAutoresizingMaskLayoutConstraint:0x1742862c0 h=--& v=--& MyApp.MyReusableView:0x101f3b590.width == 0 (active)>",
"<NSLayoutConstraint:0x174285f00 UIButton:0x102b0d040'\Uf05e'.width == 50 (active)>",
"<NSLayoutConstraint:0x174285cd0 H:|-(0)-[UIControl:0x102b22d10] (active, names: '|':UIView:0x102b38f70 )>",
"<NSLayoutConstraint:0x174285870 H:[UIButton:0x102b0d040'\Uf05e']-(0)-| (active, names: '|':UIView:0x102b38f70 )>",
"<NSLayoutConstraint:0x1742857d0 H:[UIControl:0x102b22d10]-(0)-[UIButton:0x102b0d040'\Uf05e'] (active)>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x174285f00 UIButton:0x102b0d040''.width == 50 (active)>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
What am I doing wrong with this view constraint?

Answer 1

make sure that you have set translatesAutoresizingMaskIntoConstraints to false for the view and viewController.view