AutoLayout, Unable to simultaneously satisfy constraints

Question

Just started learning iOS AutoLayout, Interface builder very straight forward, but when I try to archive the same thing on the code

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(==2)-[_nextKeyboardButton]-(==2)-[_numPadButton]-(==2)-[_spaceButton]-(==2)-[_returnButton]-(==2)-|" options:0 metrics:0 views:NSDictionaryOfVariableBindings(_nextKeyboardButton,_numPadButton,_spaceButton,_returnButton)]]; 

it raises an exception,

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:0x6000000966c0 H:|-(2)-[UIButton:0x7fe4f1d1c760'Next']   (Names: '|':UIInputView:0x7fe4f1f04d00 )>",  "<NSLayoutConstraint:0x600000096710 H:[UIButton:0x7fe4f1d1c760'Next']-(2)-[UIButton:0x7fe4f1d1d1d0'123']>",  "<NSLayoutConstraint:0x600000096760 H:[UIButton:0x7fe4f1d1d1d0'123']-(2)-[UIButton:0x7fe4f1d1d6f0'Space']>",  "<NSLayoutConstraint:0x6000000967b0 H:[UIButton:0x7fe4f1d1d6f0'Space']-(2)-[UIButton:0x7fe4f1d1d8d0'Return']>",  "<NSLayoutConstraint:0x600000096800 H:[UIButton:0x7fe4f1d1d8d0'Return']-(2)-|   (Names: '|':UIInputView:0x7fe4f1f04d00 )>",  "<NSLayoutConstraint:0x600000096e40 'UIView-Encapsulated-Layout-Width' H:[UIInputView:0x7fe4f1f04d00(0)]>"  )  Will attempt to recover by breaking constraint <NSLayoutConstraint:0x6000000967b0 H:[UIButton:0x7fe4f1d1d6f0'Space']-(2)-[UIButton:0x7fe4f1d1d8d0'Return']> 

All 4 buttons .translatesAutoresizingMaskIntoConstraints = NO;

I wonder what is wrong ? help is really appreciated :)

FYI: I work on iOS8 SDK

Answer 1

The easiest way how to find unsatisfiable constraints:

• set unique identifier for every constraint in your view:

• create simple extension for NSLayoutConstraint:

SWIFT:

extension NSLayoutConstraint {      override public var description: String {         let id = identifier ?? ""         return "id: \(id), constant: \(constant)" //you may print whatever you want here     } } 

OBJECTIVE-C

@interface NSLayoutConstraint (Description)  @end  @implementation NSLayoutConstraint (Description)  -(NSString *)description {     return [NSString stringWithFormat:@"id: %@, constant: %f", self.identifier, self.constant]; }  @end 

• build it once again, and now you have more readable output for you:

• once you got your id you can simple tap it in your Find Navigator:

• and quickly find it:

HOW TO SIMPLE FIX THAT CASE?

• try to change priority to 999 for broken constraint.

See the related answer here: Unable to simultaneously satisfy constraints, will attempt to recover by breaking constraint