CODEWITHSUNDEEP
iosobjective-cautolayoutnslayoutconstraint
Ferran Maylinch
Ferran Maylinch

Reputation: 11529

Any way to check and get NSLayoutConstraint conflicts programmatically?

EDIT: I updated the question so it is more clear.

Is there a way to check the constraints and get an NSArray of conflicting ones?

I'm working on an Autolayout helper class and I would like to print a pretty log when there are conflicts or errors.

By default, when there are layout conflicts you get a log that shows the conflicting constraints like this:

"<NSLayoutConstraint:0x7fe110638610 UILabel:0x7fe11062bb80'green'.leading == UIView:0x7fe11070de50.leadingMargin>",
"<NSLayoutConstraint:0x7fe1106386b0 H:[UILabel:0x7fe11062bb80'green'(20)]>",
"<NSLayoutConstraint:0x7fe110638660 UIView:0x7fe11070de50.trailingMargin == UILabel:0x7fe11062bb80'green'.trailing>",
"<NSLayoutConstraint:0x7fe11063fbe0 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7fe11070de50(375)]>"

I would like to get those constraints to display them in a prettier way (by view key for example). Any idea on how to do it?

Thanks!

Upvotes: 0

Views: 417

Answers (1)

matt
matt

Reputation: 535306

My book provides a couple of utility methods (implemented in a category on NSLayoutConstraint) that I like to use to log constraints when I'm debugging or exploring them:

extension NSLayoutConstraint {
    class func reportAmbiguity (var v:UIView?) {
        if v == nil {
            v = UIApplication.sharedApplication().keyWindow
        }
        for vv in v!.subviews as! [UIView] {
            println("\(vv) \(vv.hasAmbiguousLayout())")
            if vv.subviews.count > 0 {
                self.reportAmbiguity(vv)
            }
        }
    }
    class func listConstraints (var v:UIView?) {
        if v == nil {
            v = UIApplication.sharedApplication().keyWindow
        }
        for vv in v!.subviews as! [UIView] {
            let arr1 = vv.constraintsAffectingLayoutForAxis(.Horizontal)
            let arr2 = vv.constraintsAffectingLayoutForAxis(.Vertical)
            NSLog("\n\n%@\nH: %@\nV:%@", vv, arr1, arr2);
            if vv.subviews.count > 0 {
                self.listConstraints(vv)
            }
        }
    }
}

Upvotes: 1

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