> Also, I suspect the reason you're specifying center-X alignment when creating the vertical constraints is because NSLayoutConstraint threw an exception when you tried to use the center-Y alignment option. That should be warning enough. ;-)
This is true - as I typed this block into my own project I naturally lined up the "V:" vfl string with the Y constant and the "H:" vfl string with the X constant ... and it complained. I then noticed that evgenyneu<https://github.com/evgenyneu/center-vfl> had flipped them. Thanks - it now feels like this is an anomaly at best. -Luther On Fri, Oct 4, 2013 at 11:03 PM, Kyle Sluder <k...@ksluder.com> wrote: > On Fri, Oct 4, 2013, at 08:22 PM, Luther Baker wrote: > > First of all ... very much appreciate you both so often! Thanks for > > commenting as much as you do. > > > > I too faced this issue and, like Kyle, read enough to assume it was > > generally not possible with VFL. But this afternoon, I came across this: > > https://github.com/evgenyneu/center-vfl and for my specific case, it > > works > > perfectly. Let me know what you think ... and if you see caveats. I'm > > successfully using this technique to center an ImageView populated with > > an > > image much larger than the iPhone's screen on a simple, standard plain > > old > > ViewController's view. > > This doesn't work on OS X, and I'm surprised it works on iOS. > > > UIView *superview = self.view; > > NSDictionary *variables = > > NSDictionaryOfVariableBindings(label, superview); > > NSArray *constraints = [NSLayoutConstraint > > constraintsWithVisualFormat:@"V:[superview]-(<=1)-[label]" > > options: > > NSLayoutFormatAlignAllCenterX > > metrics:nil > > views:variables]; > > [self.view > > addConstraints:constraints]; > > This specifies a relationship between the superview's bottom edge and > the label's top edge, yet the label is a subview of the superview. When > running on the Mac, I would expect NSLayoutConstraint to complain here , > but I can see why it might not if the "|-" syntax is treated as a simple > shortcut for whatever the superview happens to be. > > Indeed, if you try the equivalent on the Mac, you can see that this code > throws an exception because it tries to install a constraint relating a > view to another view upon that view itself: > > """ > Unable to install constraint on view. Does the constraint reference > something from outside the subtree of the view? That's illegal. > constraint:<NSLayoutConstraint:0x104406a00 > V:[NSView:0x10060da80]-(<=1)-[NSTextField:0x10012ac00]> view:<NSView: > 0x10060da80> > """ > > I've forked the project you linked to and uploaded my demo: > <https://github.com/kylesluder/center-vfl/> > > Also, I suspect the reason you're specifying center-X alignment when > creating the vertical constraints is because NSLayoutConstraint threw an > exception when you tried to use the center-Y alignment option. That > should be warning enough. ;-) > > --Kyle Sluder > _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
