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I am trying to debug+understand autolayout constraints and I notice that when debugging the view with xcode (using the cool layer thing) I noticed that on one element in the view the constraints look like this

enter image description here

and the view is indeed ignoring these constraints.

All constraints have the same priority (1000) since I want them all. All constraints were made with interface builder and not through code, and there are not warning or conflicts in IB.

But in runtime I do see this 

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:0x79684f10 V:[UIImageView:0x79686800(>=160)]>",
    "<NSLayoutConstraint:0x7968a310 V:[UIImageView:0x79686800]-(130.5)-|   (Names: '|':UIView:0x79686790 )>",
    "<NSLayoutConstraint:0x7968a340 V:|-(0)-[UIImageView:0x79686800]   (Names: '|':UIView:0x79686790 )>",
    "<NSLayoutConstraint:0x796997b0 'UIView-Encapsulated-Layout-Height' V:[CoverCell:0x79686570(192)]>",
    "<NSAutoresizingMaskLayoutConstraint:0x7969cd30 h=-&- v=-&- UIView:0x79686790.height == CoverCell:0x79686570.height>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x79684f10 V:[UIImageView:0x79686800(>=160)]>

So from this I understand that some rules conflict, but I'm not sure how to read this

the >=160 is a rule on the UIImageView so it would have height of atleast 160 and 130.5 is the bottom padding of the imageview (so when using systemLayoutSizeFittingSize:UILayoutFittingCompressedSize the height won't be 0. So the minimum height for the entire cell is 160+130.5)

The rest of the error I don't understand.

What is wrong with the constraints and why do constraint conflicts occur in runtime and not in IB?

Nick Ginanto
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2 Answers2

6

XCode 6 now supports different layouts. This greyed out constraints exist in Compact Width | Any Height layout, for example, but you currently editing Any Width | Any Height.

More detailed: Storyboard View Elements Greyed Out

Community
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orkenstein
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1

It depends. If you don't use size classes the grey ones are the removed ones. And you need to remove them second time. No matter how stupid it sounds.

If you use size classes, it means that your current size class is different than for greyed constraint. (however the first scenario is also possible...)

In your case it looks like this is the first case. You need to remove greyed constraints once again.

b.zdybowicz
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