How to trap on UIViewAlertForUnsatisfiableConstraints

Question

I m seeing an error appear in my debugger log   Will attempt to recover by breaking constraint   lt NSLayoutConstraint 0x191f0920 H  MPKnockoutButton 0x17a876b0 - 34 - MPDetailSlider 0x17a8bc50  LTR  gt   Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger  The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in  lt UIKit UIView h gt  may also be helpful    How do I trap on that call  It does not appear anywhere in my code

User · Accepted Answer

This post helped me A LOT  I added UIViewAlertForUnsatisfiableConstraints symbolic breakpoint with suggested action  Obj-C project po   UIWindow keyWindow   autolayoutTrace    Swift project expr -l objc   -O --   UIWindow keyWindow   autolayoutTrace    With this hint  the log became more detailed  and It was easier for me identify which view had the constraint broken  UIWindow 0x7f88a8e4a4a0     UILayoutContainerView 0x7f88a8f23b70         UINavigationTransitionView 0x7f88a8ca1970             UIViewControllerWrapperView 0x7f88a8f2aab0                    UIView 0x7f88a8ca2880                      UIView 0x7f88a8ca2a10                          UIButton 0x7f88a8c98820 Archived                              UIButtonLabel 0x7f88a8cb0e30 Archived                           UIButton 0x7f88a8ca22d0 Download                              UIButtonLabel 0x7f88a8cb04e0 Download                           UIButton 0x7f88a8ca1580 Deleted                              UIButtonLabel 0x7f88a8caf100 Deleted                       UIView 0x7f88a8ca33e0                       UILayoutGuide 0x7f88a8ca35b0                       UILayoutGuide 0x7f88a8ca4090                      UIPageViewControllerContentView 0x7f88a8f1a390                          UIQueuingScrollView 0x7f88aa031c00                             UIView 0x7f88a8f38070                             UIView 0x7f88a8f381e0                                    UIView 0x7f88a8f39fa0  MISSING HOST CONSTRAINTS                                      UIButton 0x7f88a8cb9bf0 Retrieve data - AMBIGUOUS LAYOUT for UIButton 0x7f88a8cb9bf0 Retrieve data  minX id  170   UIButton 0x7f88a8cb9bf0 Retrieve data  minY id  171                                       UIImageView 0x7f88a8f3ad80- AMBIGUOUS LAYOUT for UIImageView 0x7f88a8f3ad80 minX id  172   UIImageView 0x7f88a8f3ad80 minY id  173                                       App RecordInfoView 0x7f88a8cbe530- AMBIGUOUS LAYOUT for App RecordInfoView 0x7f88a8cbe530 minX id  174   App RecordInfoView 0x7f88a8cbe530 minY id  175   App RecordInfoView 0x7f88a8cbe530 Width id  176   App RecordInfoView 0x7f88a8cbe530 Height id  177                                           UIView 0x7f88a8cc1d30- AMBIGUOUS LAYOUT for UIView 0x7f88a8cc1d30 minX id  178   UIView 0x7f88a8cc1d30 minY id  179   UIView 0x7f88a8cc1d30 Width id  180   UIView 0x7f88a8cc1d30 Height id  181                                               UIView 0x7f88a8cc1ec0- AMBIGUOUS LAYOUT for UIView 0x7f88a8cc1ec0 minX id  153   UIView 0x7f88a8cc1ec0 minY id  151   UIView 0x7f88a8cc1ec0 Width id  154   UIView 0x7f88a8cc1ec0 Height id  165                                                   UIView 0x7f88a8e68e10- AMBIGUOUS LAYOUT for UIView 0x7f88a8e68e10 minX id  155   UIView 0x7f88a8e68e10 minY id  150   UIView 0x7f88a8e68e10 Width id  156                                                   UIImageView 0x7f88a8e65de0- AMBIGUOUS LAYOUT for UIImageView 0x7f88a8e65de0 minX id  159   UIImageView 0x7f88a8e65de0 minY id  182                                                   UILabel 0x7f88a8e69080 8-6-2015 - AMBIGUOUS LAYOUT for UILabel 0x7f88a8e69080 8-6-2015  minX id  183   UILabel 0x7f88a8e69080 8-6-2015  minY id  184   UILabel 0x7f88a8e69080 8-6-2015  Width id  185                                                   UILabel 0x7f88a8cc0690 16 34 - AMBIGUOUS LAYOUT for UILabel 0x7f88a8cc0690 16 34  minX id  186   UILabel 0x7f88a8cc0690 16 34  minY id  187   UILabel 0x7f88a8cc0690 16 34  Width id  188   UILabel 0x7f88a8cc0690 16 34  Height id  189                                                   UIView 0x7f88a8cc2050- AMBIGUOUS LAYOUT for UIView 0x7f88a8cc2050 minX id  161   UIView 0x7f88a8cc2050 minY id  166   UIView 0x7f88a8cc2050 Width id  163                                                   UIImageView 0x7f88a8e69d90- AMBIGUOUS LAYOUT for UIImageView 0x7f88a8e69d90 minX id  190   UIImageView 0x7f88a8e69d90 minY id  191   UIImageView 0x7f88a8e69d90 Width id  192   UIImageView 0x7f88a8e69d90 Height id  193                                               UIView 0x7f88a8f3cc00                                                  UIView 0x7f88a8e618d0                                                  UIImageView 0x7f88a8e5ba10                                                  UIView 0x7f88a8f3cd70                                                  UIImageView 0x7f88a8e58e10                                                  UIImageView 0x7f88a8e5e7a0                                                  UIView 0x7f88a8f3cee0                                              UIView 0x7f88a8f3dc70                                                  UIView 0x7f88a8e64dd0                                                  UILabel 0x7f88a8e65290 Average flow rate                                                   UILabel 0x7f88a8e712d0 177 0 ml s                                                   UILabel 0x7f88a8c97150 1299 4                                                   UIView 0x7f88a8f3dde0                                                  UILabel 0x7f88a8f3df50 Maximum flow rate                                                   UILabel 0x7f88a8cbfdb0 371 6 ml s                                                   UILabel 0x7f88a8cc0230 873 5                                                   UIView 0x7f88a8f3e2a0                                                  UILabel 0x7f88a8f3e410 Total volume                                                   UILabel 0x7f88a8cc0f20 371 6 ml                                                   UIView 0x7f88a8f3e870                                                  UILabel 0x7f88a8f3ea00 Time do max  flow                                                   UILabel 0x7f88a8cc0ac0 3 6 s                                                   UIView 0x7f88a8f3ee10                                                  UILabel 0x7f88a8f3efa0 Flow time                                                   UILabel 0x7f88a8cbf980 2 1 s                                                   UIView 0x7f88a8f3f3e0                                                  UILabel 0x7f88a8f3f570 Voiding time                                                   UILabel 0x7f88a8cc17e0 3 5 s                                                   UIView 0x7f88a8f3f9a0                                                  UILabel 0x7f88a8f3fb30 Voiding delay                                                   UILabel 0x7f88a8cc1380 1 0 s                                                   UIView 0x7f88a8e65000                                                  UIButton 0x7f88a8e52f20 Show                                                   UIImageView 0x7f88a8e6e1d0                                                  UIButton 0x7f88a8e52c90 Send                                                   UIImageView 0x7f88a8e61bb0                                                  UIButton 0x7f88a8e528e0 Delete                                                   UIImageView 0x7f88a8e6b3f0                                                  UIView 0x7f88a8f3ff60                                      UIActivityIndicatorView 0x7f88a8cba080                                         UIImageView 0x7f88a8cba700                                       UILayoutGuide 0x7f88a8cc3150                                       UILayoutGuide 0x7f88a8cc3b10                             UIView 0x7f88a8f339c0         UINavigationBar 0x7f88a8c96810              UINavigationBarBackground 0x7f88a8e45c00                 UIImageView 0x7f88a8e46410             UINavigationItemView 0x7f88a8c97520 App                  UILabel 0x7f88a8c97cc0 App              UINavigationButton 0x7f88a8e3e850                 UIImageView 0x7f88a8e445b0              UINavigationBarBackIndicatorView 0x7f88a8f2b530  Legend        - is laid out with auto layout       - is laid out manually  but is represented in the layout engine because translatesAutoresizingMaskIntoConstraints   YES         - layout engine host  Then I paused execution    and I changed problematic view s background color with the command  replacing 0x7f88a8cc2050 with the memory address of your object of course     Obj-C expr   UIView   0x7f88a8cc2050  backgroundColor    UIColor redColor   Swift 3 0 expr -l Swift -- import UIKit expr -l Swift -- unsafeBitCast 0x7f88a8cc2050  to  UIView self  backgroundColor   UIColor red      and the result It was awesome   Simply amazing  Hope It helps

User · Answer

This usually appears when you want to use UIActivityViewController in iPad.

Add below, before you present the controller to mark the arrow.

activityViewController.popoverPresentationController?.sourceRect = senderView.frame // senderView can be your button/view you tapped to call this VC

I assume you already have below, if not, add together:

activityViewController.popoverPresentationController?.sourceView = self.view

User · Answer

You ll want to add a Symbolic Breakpoint   Apple provides an excellent guide on how to do this      Open the Breakpoint Navigator cmd 7  cmd 8 in Xcode 9  Click the Add button in the lower left Select Add Symbolic Breakpoint    Where it says Symbol just type in UIViewAlertForUnsatisfiableConstraints   You can also treat it like any other breakpoint  turning it on and off  adding actions  or log messages

User · Answer

Followed Stephen s advice and tried to debug the code and whoa  it worked  The answer lies in the debug message itself   Will attempt to recover by breaking constraint  NSLayoutConstraint 0x191f0920 H  MPKnockoutButton 0x17a876b0 - 34 - MPDetailSlider 0x17a8bc50  LTR  gt   The line above tells you that the runtime worked by removing this constraint  May be you don t need Horizontal Spacing on your button  MPKnockoutButton   Once you clear this constraint  it won t complain at runtime  amp  you would get the desired behaviour

User · Answer

Whenever I attempt to remove the constraints that the system had to break  my constraints are no longer enough to satisfy the IB  ie  missing constraints  shows in the IB  which means they re incomplete and won t be used   I actually got around this by setting the constraint it wants to break to low priority  which  and this is an assumption  allows the system to break the constraint gracefully  It s probably not the best solution  but it solved my problem and the resulting constraints worked perfectly

[ios] How to trap on UIViewAlertForUnsatisfiableConstraints?

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