A tool to understand constraints warnings, only adding it as a dependency.
Without ConstraintsMonitor:
[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:0x600003220d20 h=--& v=--& ConstraintsMonitor_Example.MyView:0x7fcdaff03e10.height == 896 (active)>", "<NSLayoutConstraint:0x600003220a50 UIView:0x7fcdaff031e0.height == 200 (active)>", "<NSLayoutConstraint:0x600003220410 V:|-(0)-[UIView:0x7fcdaff031e0] (active, names: '|':ConstraintsMonitor_Example.MyView:0x7fcdaff03e10 )>", "<NSLayoutConstraint:0x600003220aa0 V:[UIView:0x7fcdaff031e0]-(0)-[UIView:0x7fcdaff03fc0] (active)>", "<NSLayoutConstraint:0x600003220b90 UIView:0x7fcdaff03fc0.bottom == ConstraintsMonitor_Example.MyView:0x7fcdaff03e10.bottom (active)>", "<NSLayoutConstraint:0x600003220be0 UIView:0x7fcdaff03fc0.height == 0.2*ConstraintsMonitor_Example.MyView:0x7fcdaff03e10.height (active)>" ) Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600003220a50 UIView:0x7fcdaff031e0.height == 200 (active)> With ConstraintsMonitor:
[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) ( "UIViewControllerWrapperView.MyView.height == 896.0 (Did you set translatesAutoresizingMaskIntoConstraints = false?)", "MyView.UIView.height == 200.0 ", "MyView.UIView.top == UIViewControllerWrapperView.MyView.top (constant: 0.0)", "MyView.UIView.top == UIView.bottom (constant: 0.0)", "MyView.UIView.bottom == UIViewControllerWrapperView.MyView.bottom (constant: 0.0)", "MyView.UIView.height == UIViewControllerWrapperView.MyView.height (multiplier: 0.200)" ) Will attempt to recover by breaking constraint MyView.UIView.height == 200.0 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. I was tired of looking for constraints issues and realizing what was really the issue, so I created this mini tool for printing nicer constraints
pod 'ConstraintsMonitor'dependencies: [ .package(url: "https://github.com/FranDepascuali/ConstraintsMonitor.git", from: "1.0.1") ]Just by including this lib in your project, you will see nicer constraints warnings
- Use an identifier for the constraint if supplied.
- Use the view identifier or the class name if the view is a subclass of UIView.
- Show the parent view, so it's easier to know where to locate the issue.
By overriding the description property of the NSLayoutConstraint involved, we have a nicer way of viewing constraints.
You can check my blog at https://deep-thought.netlify.com/ or @FranDepascuali in twitter.
ConstraintsMonitor is available under the MIT license. See the LICENSE file for more info.