Re: Autolayout warnings
Re: Autolayout warnings
- Subject: Re: Autolayout warnings
- From: Doug Hill <email@hidden>
- Date: Wed, 14 Dec 2016 14:52:33 -0800
Gary,
Thanks for the reply.
I tried moving the container rather than resizing to 0 because there's a table inside this view and it will relayout when resizing. For an animation, I guess it depends on what effect you want: either seeing the view move or resize to 0.
Oddly, when I put my code to activate/deactivate constraints inside a [UIView animateWithDuration…] I get no animation. :(
Doug Hill
> On Dec 14, 2016, at 2:49 PM, Gary L. Wade <email@hidden> wrote:
>
> If I understand you correctly, you might prefer the approach I chose to do. Rather than activating and deactivating constraints (BTW, you should always deactivate before having multiple actives), set your constraints up to always be active but change the width for the one you’re hiding to 0 and the other to be the extra size needed to fill the gap. I also chose to animate the constant values, so the size-change is smooth to the user.
> --
> Gary L. Wade
> http://www.garywade.com/ <http://www.garywade.com/>
>> On Dec 14, 2016, at 2:19 PM, Doug Hill <email@hidden <mailto:email@hidden>> wrote:
>>
>> I'm seeing warnings in the console when I dynamically make autolayout constraints active/inactive at runtime.
>>
>> I have two constraints that align a container view leading or trailing edge with another view's edge. This is to move the container onscreen or offscreen. I have another view whose trailing edge aligns with the leading edge of the first container view so it moves with it as autolayout constraints change.
>>
>> At runtime, I make one of these constraints active and the other inactive, like so:
>>
>> - (IBAction)toggleCommentsVisibility:(id)sender
>> {
>> self.commentsAreHidden ? [self showComments:self] : [self hideComments:self];
>> }
>>
>> - (IBAction)showComments:(id)sender
>> {
>> self.showCommentsConstraint.active = YES;
>> self.hideCommentsContainerConstraint.active = NO;
>>
>> self.commentsAreHidden = NO;
>> }
>>
>> - (IBAction)hideComments:(id)sender
>> {
>> self.showCommentsConstraint.active = NO;
>> self.hideCommentsContainerConstraint.active = YES;
>>
>> self.commentsAreHidden = YES;
>> }
>>
>> When I call showComments, I get the following warning in the console:
>>
>> =====
>>
>> 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.
>> (
>> "<NSLayoutConstraint:0x7f91426a3ef0 'CommentContainerProportionalWidth' UIView:0x7f91426d9db0.width == 0.33*UIView:0x7f91426def30.width>",
>> "<NSLayoutConstraint:0x7f91426c91e0 'Hide Comments Constraint' H:[UIView:0x7f91426d7f00]-(0)-[UIView:0x7f91426d9db0]>",
>> "<NSLayoutConstraint:0x7f91426e2990 'ShowComments' UIView:0x7f91426d9db0.trailing == UIView:0x7f91426d7f00.trailing>",
>> "<NSLayoutConstraint:0x7f91427e43c0 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7f91426def30(768)]>"
>> )
>>
>> Will attempt to recover by breaking constraint
>> <NSLayoutConstraint:0x7f91426c91e0 'Hide Comments Constraint' H:[UIView:0x7f91426d7f00]-(0)-[UIView:0x7f91426d9db0]>
>>
>> Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
>>
>> =====
>>
>> This is puzzling because IB doesn't give me any autolayout errors/warning when I manually activate/deactivate these constraints. Also, I don't get this runtime warning when calling hideComments, only the 'show' case. Finally, things actually work at runtime because it's nice enough to "break" the constraint that I deactivated in code. But I would like to not have these warnings.
>>
>> Any ideas on what's going on how I might go about debugging this?
>>
>> Doug Hill
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