Sequence of constraint activation/deactivation matters

gistfile1.txt

-(void)updateConstraints
{
    [super updateConstraints];
    if (self.binaryFiles.count > 0)
    {
        //deactivate first, then activate, then change constant
        [NSLayoutConstraint deactivateConstraints: @[self.attachmentButtonConstraintHeight]];
        [NSLayoutConstraint activateConstraints: @[self.attachmentButtonConstraintAspectRatio]];
//        self.attachmentButtonConstraintHeight.active = NO;
//        self.attachmentButtonConstraintAspectRatio.active = YES;
    }
    else
    {
        [NSLayoutConstraint deactivateConstraints: @[self.attachmentButtonConstraintAspectRatio]];
        [NSLayoutConstraint activateConstraints: @[self.attachmentButtonConstraintHeight]];
        //changing constraint constant will trigger recalculation of layout and constraints conflict warnings if there are any.
        self.attachmentButtonConstraintHeight.constant = 0;
    }
    
}