iOS 8.3 'UIView-Encapsulated-Layout-Width' in Custom Keyboard

Question

I have implemented a custom keyboard. It works fine on a device which runs iOS 8.2.

However, when I run the same code on a device with iOS 8.3 I get the following warnings and the height of the keyboard is not set properly:

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:0x15dd1da0 h=-&- v=-&- Keyboard:0x15db2b00.width == UIView:0x15da7b90.width - 320>",
    "<NSLayoutConstraint:0x15dd2520 'UIView-Encapsulated-Layout-Width' H:[UIView:0x15da7b90(0)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x15dd2520 'UIView-Encapsulated-Layout-Width' H:[UIView:0x15da7b90(0)]>

I have no idea what this means. Please help me figure it out.

Answer 1

    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:0x15dd1da0 h=-&- v=-&- Keyboard:0x15db2b00.width == UIView:0x15da7b90.width - 320>",
    "<NSLayoutConstraint:0x15dd2520 'UIView-Encapsulated-Layout-Width' H:[UIView:0x15da7b90(0)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x15dd2520 'UIView-Encapsulated-Layout-Width' H:[UIView:0x15da7b90(0)]>

It is telling you that it can't satisfy all constraints at once.

You have a constraint <NSAutoresizingMaskLayoutConstraint:0x15dd1da0 h=-&- v=-&- Keyboard:0x15db2b00.width == UIView:0x15da7b90.width - 320>, which dictates the width of the keyboard equals the width of the UIView at 0x15da7b90 minus 320 (check the debugger which one this is, I usually look at the GUI debugger if I know what UIViews might be causing the problem).

The other conflicting constraint is <NSLayoutConstraint:0x15dd2520 'UIView-Encapsulated-Layout-Width' H:[UIView:0x15da7b90(0)]>, which dictates the width of the UIView at 0x15da7b90 (same one) to be 0. It cannot satisfy both this one and the one above, so it breaks this one.

I see that your first constraint is one of the type NSAutoresizingMaskLayoutConstraint, so you can try to set setTranslatesAutoresizingMaskIntoConstraints to false on your view, which will probably remove the first constraint, thus removing the conflict.

Other helpful documentation:

• Visual Format Language, the format that Xcode uses in the log, helps to know this language to debug them better.
• View Debugging in Xcode, helps to identify which views are where and at what address.