AutoLayout constraint issue with unexpected NSAutoresizingMaskLayoutConstraint

Question

I'm using auto layout constraints programmatically and I am constantly seeing the same kind of error across my application usually related to a constraint that looks like this:

"<NSAutoresizingMaskLayoutConstraint:0x82da910 h=--& v=--& V:[UITableViewCellContentView:0x82d9fb0(99)]>"

I've put some sample code to reproduce at https://github.com/nicolasccit/AutoLayoutCellWarning

In this example, I am creating a very simple view with 2 UI elements: an image view called imageThumbnail and a label called labelName with some constraints:

"H:|-padding-[_imageThumbnail(==imageWidth)]-[_labelName]";
"V:|-padding-[_imageThumbnail(==imageHeight)]-padding-|";
"V:|-padding-[_labelName]";

On both elements I set the AutoresizingMaskIntoConstraints to NO.

And I am getting the following exception:

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:0xa6e4f90 V:[UIImageView:0xa6e4340]-(10)-|   (Names: '|':UITableViewCellContentView:0xa6e4150 )>",
    "<NSLayoutConstraint:0xa6e4f10 V:[UIImageView:0xa6e4340(80)]>",
    "<NSLayoutConstraint:0xa6e4ed0 V:|-(10)-[UIImageView:0xa6e4340]   (Names: '|':UITableViewCellContentView:0xa6e4150 )>",
    "<NSAutoresizingMaskLayoutConstraint:0xa6e4ac0 h=--& v=--& V:[UITableViewCellContentView:0xa6e4150(99)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0xa6e4f90 V:[UIImageView:0xa6e4340]-(10)-|   (Names: '|':UITableViewCellContentView:0xa6e4150 )>

I know the last constraint is related to the content view but I am unclear to properly remove it (Setting
AutoresizingMaskIntoConstraints to NO on the contentView raises an error and in the SO link below, it messes up the entire layout):

<NSAutoresizingMaskLayoutConstraint:0xa6e4ac0 h=--& v=--& V:[UITableViewCellContentView:0xa6e4150(99)]>

I've seen the answers at: Auto layout constraints issue on iOS7 in UITableViewCell but none of them seem to be working for me here.

I believe that the constraints I define are valid and pretty straightforward but can't seem to figure out what's going on. And I'm seeing the exception being raised both in iOS 6.1 and iOS 7.

Any idea what I am doing wrong here?

Thanks, Nicolas

Answer 1

You should read the exception description more thoroughly:

Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints

In short, this constraint you are seeing is due to some UIView having it's translatesAutoresizingMaskIntoConstraints set to YES. In this case I would suspect this is the content view of the cell, as hinted to by UITableViewCellContentView.

You can disable it by just setting the property to NO.

cell.contentView.translatesAutoresizingMaskIntoConstraints = NO

EDIT: Now, keep in mind that this is a temporary fix, most likely you have some other logic error with your constraints, for example constraining something in the contentView of the cell to the cell itself. Or by seemingly forcing the contentView to be larger than the cell is (and therefore larger than its' automatic sizing is).

For example, is your cell tall enough? i.e is it tall enough so that the contentView is 100pt tall? Note that the contentView has to be that tall, which might not necessarily match the height of the cell.