Unable to simultaneously satisfy constraints - No

Question

I have gone through and removed every single user constraint yet I am still getting the following error ONLY after I rotate the device. I have absolutely no clue why though. Does anyone have any ideas?

2013-01-14 21:30:31.363 myApp[35869:c07] 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:0x84543d0 h=--& v=--& V:[UIView:0xa330270(768)]>",
    "<NSLayoutConstraint:0xa338350 V:[UIView:0xa331260]-(-1)-|   (Names: '|':UIView:0xa330270 )>",
    "<NSLayoutConstraint:0xa338390 V:|-(841)-[UIView:0xa331260]   (Names: '|':UIView:0xa330270 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0xa338350 V:[UIView:0xa331260]-(-1)-|   (Names: '|':UIView:0xa330270 )>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

Answer 1

I had this problem and took me 2 days to figure out the source of the problem....

If you open a storyboard programmatically in you code just make sure you do it like this:

UIStoryboard *story = [UIStoryboard storyboardWithName:@"MovieMaker" bundle:nil];
    UIViewController *vc = [story instantiateInitialViewController];
    //this causes layout to break [self presentViewController:vc animated:YES completion:nil];
    [self showViewController:vc sender:nil];

I was using the commented line (using presentViewController) and the orientation bug has happening throwing constraints conflicts that weren't my constraints... changing to showViewController all constraints conflicts were gone and orientation works...... (I don't really know why it works with show and not present... still thinking it's... ALIENS...)

Answer 2

thanks to http://useYourLoaf.com for this complete solution:

http://useyourloaf.com/blog/using-identifiers-to-debug-autolayout.html

A quick tip I found buried in a WWDC 2015 session on Auto Layout that helps when debugging problems with constraints

If you have used Auto Layout you will be familiar with the log that Xcode spits out when you get something wrong. To create an example I modified my Stack View sample code and added a constraint to each of the images to give them a fixed width of 240 (not a good idea as we will see).

That works in regular width views such as the iPad but is too wide for a compact width view such as the iPhone in portrait. The console log at runtime is not fun to read. Skipping the boilerplate text you get a list of the problematic constraints:

"<NSLayoutConstraint:0x7fc1ab520360 H:[UIImageView:0x7fc1ab532650(240)]>",
"<NSLayoutConstraint:0x7fc1ab536ef0 H:[UIImageView:0x7fc1ab537380(240)]>",
"<NSLayoutConstraint:0x7fc1ab545cc0 UIView:0x7fc1ab53d870.trailingMargin == UIStackView:0x7fc1ab53dae0.trailing>",
"<NSLayoutConstraint:0x7fc1ab545d10 UIStackView:0x7fc1ab53dae0.leading == UIView:0x7fc1ab53d870.leadingMargin>",
"<NSLayoutConstraint:0x7fc1ab54e240 'UISV-alignment' UIStackView:0x7fc1ab53dc70.centerX == UIStackView:0x7fc1ab531a10.centerX>",
"<NSLayoutConstraint:0x7fc1ab5167c0 'UISV-canvas-connection' UIStackView:0x7fc1ab531a10.leading == UIImageView:0x7fc1ab532650.leading>",
"<NSLayoutConstraint:0x7fc1ab54ad80 'UISV-canvas-connection' H:[UIImageView:0x7fc1ab537380]-(0)-|   (Names: '|':UIStackView:0x7fc1ab531a10 )>",
"<NSLayoutConstraint:0x7fc1ab5397d0 'UISV-canvas-connection' UIStackView:0x7fc1ab53dae0.leading == _UILayoutSpacer:0x7fc1ab54c3c0'UISV-alignment-spanner'.leading>",
"<NSLayoutConstraint:0x7fc1ab54a4a0 'UISV-canvas-connection' UIStackView:0x7fc1ab53dae0.centerX == UIStackView:0x7fc1ab53dc70.centerX>",
"<NSLayoutConstraint:0x7fc1ab54b110 'UISV-spacing' H:[UIImageView:0x7fc1ab532650]-(16)-[UIImageView:0x7fc1ab537380]>",
"<NSLayoutConstraint:0x7fc1ab548210 'UISV-spanning-boundary' _UILayoutSpacer:0x7fc1ab54c3c0'UISV-alignment-spanner'.leading <= UIStackView:0x7fc1ab531a10.leading>",
"<NSLayoutConstraint:0x7fc1ab551690 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7fc1ab53d870(375)]>"

The log then tells you which of the above constraints it has decided to break:

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7fc1ab536ef0 H:[UIImageView:0x7fc1ab537380(240)]>

The log output uses the auto layout visual format language but it is hard to pick out my constraints from those created by the system. This is especially the case with stack views which are by design intended to create most of the constraints for you. In this trivial example I know the fixed width constraints that I just added broke things but it is hard to see that from the log and the more complex the view the harder it gets.

Adding an Identifier to a Constraint

The log gets a lot easier to understand if you add an identifier to each constraint (NSLayoutConstraint has had an identifier property since iOS 7). In Interface Builder find the constraint and add the identifier in the Attributes inspector (I am using $ as a prefix/suffix to make them stand out in the log):

Update 18-August-2015: As pointed out in the comments the identifier can only be edited in Interface Builder starting with Xcode 7. It is not visible in Xcode 6.4.

If adding the constraint in code:

constraint.identifier = "$HeartImageFixedWidth$"

It is trickier if you are using the visual format language which uses arrays of constraints. For example, consider the Swift code fragment to create a fixed width constraint for the heart image view:

let heartWidth = NSLayoutConstraint.constraintsWithVisualFormat("[heart(240)]", 
                 options:[], metrics:nil, views:viewsDictionary)

Since heartWidth is an array of type [NSLayoutConstraint] setting the identifier is a little more work:

for constraint in heartWidth {
  constraint.identifier = "$HeartImageFixedWidth$"
}
heartImage.addConstraints(heartWidth)

With identifies set for my constraints it is now much easier to find them in the log file (see the first four lines):

"<NSLayoutConstraint:0x7f92a305aeb0 '$ContainerStackViewLeading$' UIStackView:0x7f92a3053220.leading == UIView:0x7f92a3052fb0.leadingMargin + 32>",
"<NSLayoutConstraint:0x7f92a305b340 '$ContainerStackViewTrailing$' UIView:0x7f92a3052fb0.trailingMargin == UIStackView:0x7f92a3053220.trailing + 32>",
"<NSLayoutConstraint:0x7f92a301cf20 '$HeartImageFixedWidth$' H:[UIImageView:0x7f92a3047ef0(240)]>",
"<NSLayoutConstraint:0x7f92a3009be0 '$StarImageFixedWidth$' H:[UIImageView:0x7f92a304d190(240)]>",
"<NSLayoutConstraint:0x7f92a3060cc0 'UISV-alignment' UIStackView:0x7f92a30533b0.centerX == UIStackView:0x7f92a30472b0.centerX>",
"<NSLayoutConstraint:0x7f92a301c590 'UISV-canvas-connection' UIStackView:0x7f92a30472b0.leading == UIImageView:0x7f92a3047ef0.leading>",
"<NSLayoutConstraint:0x7f92a305f680 'UISV-canvas-connection' H:[UIImageView:0x7f92a304d190]-(0)-|   (Names: '|':UIStackView:0x7f92a30472b0 )>",
"<NSLayoutConstraint:0x7f92a3064190 'UISV-canvas-connection' UIStackView:0x7f92a3053220.leading == _UILayoutSpacer:0x7f92a30608a0'UISV-alignment-spanner'.leading>",
"<NSLayoutConstraint:0x7f92a30415d0 'UISV-canvas-connection' UIStackView:0x7f92a3053220.centerX == UIStackView:0x7f92a30533b0.centerX>",
"<NSLayoutConstraint:0x7f92a305fa10 'UISV-spacing' H:[UIImageView:0x7f92a3047ef0]-(16)-[UIImageView:0x7f92a304d190]>",
"<NSLayoutConstraint:0x7f92a30508c0 'UISV-spanning-boundary' _UILayoutSpacer:0x7f92a30608a0'UISV-alignment-spanner'.leading <= UIStackView:0x7f92a30472b0.leading>",
"<NSLayoutConstraint:0x7f92a3063240 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7f92a3052fb0(375)]>"

It also much clearer which of the constraints the system has chosen to break:

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7f92a3009be0 '$StarImageFixedWidth$' H:[UIImageView:0x7f92a304d190(240)]>

Adding identifiers to constraints is not without effort but it can pay off the next time you have to sort through the debug log of a complex layout.

Further Reading

• WWDC 2015 Session 219 Mysteries of Auto Layout, Part 2

Answer 3

YourConstraintView.translatesAutoresizingMaskIntoConstraints = NO;

Did it for me.

Answer 4

I guess this is not a common error, but I solved it somewhat in a layman way. I was getting cryptic messages like the one above. To make sense of it, I created dummy view classes and attached it to the views in my storyboard. For example, if I had a UIView, I created a class called AddressView and attached it to this view in story board. Its a bit time consuming, but it worked for me. After that instead of object-ids, I got class names which helped me zero in on the views that were causing the issue very easily. My error message now read,

2013-07-02 04:16:20.434 Myproject [2908:c07] 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) 
(
    "<NSLayoutConstraint:0x9edeae0 V:|-(0)-[AddressView:0x143ee020]   (Names: '|':MainView:0x129eb6a0 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x11e998c0 h=--& v=--& V:[MainView:0x129eb6a0(704)]>",
    "<NSLayoutConstraint:0x156720b0 V:[AddressView:0x143ee020]-(896)-|   (Names: '|':MainView:0x129eb6a0 )>"
)

Here you can see, the names of my views MainView and Address view are causing the issue.

To resolve it, I just moved my subview (in this case Address view) and repositioned it back. I think the issue began as I was using a mix of new Automatic Layour in Xcode 4.5 and old skills or manually positioning the views.

Anyways, not sure if it was more luck than diligence, but nevertheless this could be a different way of debugging. Maybe this helps someone!