AutoLayout: removeFromSuperview / removeConstraints создает исключение и аварийно завершает работу

мы используем ограничения автоматической компоновки выборочно, в первую очередь для размещения меток по отношению к редактируемым элементам поля (UITextView, UITextField, как правило). Однако с момента реализации автоматического макета для этих полей мы видим неприятное исключение и сбой при выгрузке представлений, освобождении и т. д. Исключения происходят, когда он пытается удалить ограничения из представления перед его выгрузкой.

наша иерархия представления/контроллера выглядит следующим образом такие:

UITableViewController (plain style, but with cell appearance to mimic grouped style)

--> UITableViewCell

----> UIViewController (container for editable form)

------> UICollectionViewController (editable form)

--------> UICollectionViewCell

-----------> UIViewController (editable field)

--------------> UILabel (field label)                   **HAS CONSTRAINTS**

--------------> UITextView / UITextField (field value)  **HAS CONSTRAINTS**

много раз, когда ячейки таблицы верхнего уровня освобождаются/заменяются/перезагружаются, мы видим огромное исключение, а затем сбой, когда он пытается освободить/выгрузить иерархию представления внутри.

Я попытался смягчить сбой, поймав исключение (без помощи) , а также принудительно удалив все ограничения на затронутое представление и все подвиды до освобождения / выгрузки (в viewWillDisappear:) и это, кажется, не помогает. Я даже пробовал чтобы удалить эти ограничения один за другим, чтобы увидеть, если есть один в частности, что вызывает проблемы, но все они взрываются, когда мы называем removeConstraint: или removeConstraints: на контейнере в процессе подготовки к исчезновению.

Я сбит с толку! Вот фрагмент нашего исключения-примерно около 3000 строк были вырезаны из него, так что если вам нужно больше, просто спросите.

Exception while deallocating view: { Rows:

    0x18911270.posErrorMarker == 4 + 1*0x18911270.negError + 1*0x189112f0.marker + -1*0x189113f0.negError + 1*0x189113f0.posErrorMarker + 1*0x18911a60.marker + -0.5*0x1892dae0.negError + 0.5*0x1892dae0.posErrorMarker + 1*0x18951520.negError + -1*0x18951520.posErrorMarker + -0.5*0x18958090.negError + 0.5*0x18958090.posErrorMarker

    0x189112b0.negError == 12 + 1*0x189112b0.posErrorMarker + -1*0x189112f0.marker + 1*0x189113f0.negError + -1*0x189113f0.posErrorMarker + -1*0x18911a60.marker + 1*0x18925530.marker + 0.5*0x1892dae0.negError + -0.5*0x1892dae0.posErrorMarker + 1*0x1893e080.marker + 0.5*0x18958090.negError + -0.5*0x18958090.posErrorMarker + 1*0x18963640.marker

    0x18911370.negError == 9 + -1*0x189112f0.marker + 1*0x18911370.posErrorMarker + 1*0x18925530.marker + 1*0x1892dae0.negError + -1*0x1892dae0.posErrorMarker + 1*0x1893e080.marker + 1*0x18963640.marker

    0x189113b0.slackMarker == 2 + -1*0x189107d0.marker + 1*0x18910b90.negError + -1*0x18910b90.posErrorMarker + 



      ........ EXPLETIVES DELETED .........



   UITableView:0xca2b000.contentHeight == 36 + 1*0xc221c00.marker

   UITableView:0xca2b000.contentWidth == 704 + 1*0xc239470.marker

   UITableView:0xca2b000.minX == 0 + 1*0xc2a23f0.marker + -0.5*0xc2a2590.marker

   UITableView:0xca2b000.minY == 0 + 1*0xc2a25d0.marker + -0.5*0xc2a2630.marker

   UITableViewCellContentView:0x18ab13d0.Height == 174 + 1*0x18abd4f0.marker

   UITableViewCellContentView:0x18ab13d0.Width == 704 + 1*0x18abd470.marker



      ........ EXPLETIVES DELETED .........



    <NSAutoresizingMaskLayoutConstraint:0x18988bc0 h=-&- v=-&- UIView:0x18911e50.midY == UIView:0x1892d0c0.midY>        Marker:0x18988bc0.marker

    <NSAutoresizingMaskLayoutConstraint:0x18994b40 h=-&- v=-&- UIView:0xc4a6fb0.midX == UIView:0xc4b4990.midX>      Marker:0x18994b40.marker

    <NSAutoresizingMaskLayoutConstraint:0x18998480 h=-&- v=-&- UIView:0x18915180.width == UIView:0xc4c5970.width>       Marker:0x18998480.marker

    <NSAutoresizingMaskLayoutConstraint:0x18aae320 h=--& v=--& TapSectionalTableViewCell:0x18a3d270.midX == + 352>      Marker:0x18aae320.marker

    <NSAutoresizingMaskLayoutConstraint:0x18aae410 h=--& v=--& H:[TapSectionalTableViewCell:0x18a3d270(704)]>       Marker:0x18aae410.marker

    <NSAutoresizingMaskLayoutConstraint:0x18aae450 h=--& v=--& TapSectionalTableViewCell:0x18a3d270.midY == + 144>      Marker:0x18aae450.marker



      ........ EXPLETIVES DELETED .........



    <NSAutoresizingMaskLayoutConstraint:0xc2de2f0 h=--& v=--& TapGenericCollectionCell:0xc2ac500.midX == + 499>     Marker:0xc2de2f0.marker

    <NSAutoresizingMaskLayoutConstraint:0xc2de3b0 h=--& v=--& V:[TapGenericCollectionCell:0xc2ac500(34)]>       Marker:0xc2de3b0.marker

    <NSAutoresizingMaskLayoutConstraint:0xc2de430 h=-&- v=-&- UIView:0x18953f80.height == UIView:0xc2acb20.height>      Marker:0xc2de430.marker

    <NSAutoresizingMaskLayoutConstraint:0xc2de520 h=-&- v=-&- UIView:0x18923af0.height == UIView:0xc2ae570.height>      Marker:0xc2de520.marker

    <NSAutoresizingMaskLayoutConstraint:0xc2de560 h=--& v=--& H:[TapGenericCollectionCell:0xc2ac500(280)]>      Marker:0xc2de560.marker



      ........ EXPLETIVES DELETED .........



    <NSContentSizeLayoutConstraint:0xc2f5730 H:[_UIBaselineLayoutStrut:0x18994a30(0)] Hug:250 CompressionResistance:750>        Marker:0xc2f5730.posErrorMarker

    <NSContentSizeLayoutConstraint:0xc2f5730 H:[_UIBaselineLayoutStrut:0x18994a30(0)] Hug:250 CompressionResistance:750>        Marker:0xc2f5730.posErrorMarker

    <NSContentSizeLayoutConstraint:0xc2f5770 V:[_UIBaselineLayoutStrut:0x18994a30(18)] Hug:250 CompressionResistance:750>       Marker:0xc2f5770.posErrorMarker



internal error.  Cannot find an outgoing row head for incoming head UIView:0x189712b0.Width, which should never happen.'

/**** BEGIN Individual Field Controller - This code is from the base individual field controller used in our editable form collection *****/



- (void)viewDidLoad {

    [super viewDidLoad];

    self.view.clipsToBounds = YES;

    self.view.opaque = YES;



    CGRect viewFrame = self.view.frame;

    viewFrame.size = [self defaultFieldSize];

    self.view.frame = viewFrame;



    if (self.backgroundColor) {

        self.view.backgroundColor = self.backgroundColor;

    }

    else {

        self.view.backgroundColor = [UIColor whiteColor];

    }

    [self createLabelAndField];



    [self setLabelAndFieldContraints];



    [self.view addConstraints:self.labelValueConstraints];

    [self.view setNeedsUpdateConstraints];

}



- (void)createLabelAndField {

    [self removeLabelAndField];



    UILabel *label = [[UILabel alloc] init];

    label.font = self.labelFont;

    label.textColor = self.labelColor;

    label.lineBreakMode = NSLineBreakByWordWrapping;

    label.textAlignment = NSTextAlignmentLeft;

    label.adjustsFontSizeToFitWidth = NO;

    label.numberOfLines = 0;



    if (self.backgroundColor) {

        label.backgroundColor = self.backgroundColor;

    }

    else {

        label.backgroundColor = [UIColor whiteColor];

    }



    [self.view addSubview:label];



    self.label = label;





    /// EXAMPLE valueView initialization from a subclass that handles long text



    TapEditableTextView *textView = [[TapEditableTextView alloc] init];

    if (self.hasLabelOverValue) {

        textView.shouldMimicTextField = NO;

    }

    else {

        textView.shouldMimicTextField = YES;

    }

    textView.delegate = self;

    textView.keyboardType = UIKeyboardTypeDefault;

    textView.font = self.valueFont;

    textView.textColor = self.valueColor;

    textView.textAlignment = NSTextAlignmentLeft;

    textView.normalBackgroundColor = self.backgroundColor;

    textView.editable = NO;

    textView.textLines = self.textLines;



    self.valueTextView = textView;

    self.valueView = textView;

    [self.view addSubview:textView];

}



- (void)removeLabelAndField {

    [self clearConstraints];



    if (self.label) {

        [self.label removeFromSuperview];

        self.label = nil;

    }

    if (self.valueView) {

        [self.valueView removeFromSuperview];

        self.valueView = nil;

    }

}



- (void)clearConstraints {

    if (self.isViewLoaded && self.labelValueConstraints) {

        [self.view removeConstraints:self.labelValueConstraints];

    }

    self.labelValueConstraints = nil;

    self.labelToValueHorizConstraint = nil;

    self.valueWidthConstraint = nil;

}



// This is called in our field's viewDidLoad, after we've created our label and valueView (UITextField, UITextView, etc)

- (void)setLabelAndFieldContraints {

    [self clearConstraints];



    self.labelValueConstraints = [NSMutableArray array];



    self.label.translatesAutoresizingMaskIntoConstraints = NO;

    self.valueView.translatesAutoresizingMaskIntoConstraints = NO;



    NSLayoutConstraint *constraint = nil;



    constraint = [NSLayoutConstraint

                  constraintWithItem:self.label attribute:NSLayoutAttributeLeft

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.view attribute:NSLayoutAttributeLeft

                  multiplier:1.0f constant:self.labelValueGap];

    constraint.priority = UILayoutPriorityRequired;

    [self.labelValueConstraints addObject:constraint];





    constraint = [NSLayoutConstraint

                  constraintWithItem:self.label attribute:NSLayoutAttributeTop

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.view attribute:NSLayoutAttributeTop

                  multiplier:1.0f constant:0];

    constraint.priority = 550;

    [self.labelValueConstraints addObject:constraint];





    constraint = [NSLayoutConstraint

                  constraintWithItem:self.label attribute:NSLayoutAttributeBottom

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.view attribute:NSLayoutAttributeBottom

                  multiplier:1.0f constant:0];

    constraint.priority = 400;

    [self.labelValueConstraints addObject:constraint];





    constraint = [NSLayoutConstraint

                  constraintWithItem:self.valueView attribute:NSLayoutAttributeTop

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.view attribute:NSLayoutAttributeTop

                  multiplier:1.0f constant:0];

    constraint.priority = UILayoutPriorityRequired;

    [self.labelValueConstraints addObject:constraint];





    constraint = [NSLayoutConstraint

                  constraintWithItem:self.valueView attribute:NSLayoutAttributeBottom

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.view attribute:NSLayoutAttributeBottom

                  multiplier:1.0f constant:0];

    constraint.priority = 499;

    [self.labelValueConstraints addObject:constraint];





     constraint = [NSLayoutConstraint

                  constraintWithItem:self.valueView attribute:NSLayoutAttributeRight

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.view attribute:NSLayoutAttributeRight

                  multiplier:1.0f constant: -(kDisclosureWidth + self.labelValueGap) ];

     constraint.priority = 901;

     [self.labelValueConstraints addObject:constraint];





    constraint = [NSLayoutConstraint

                  constraintWithItem:self.valueView attribute:NSLayoutAttributeLeading

                  relatedBy:NSLayoutRelationGreaterThanOrEqual

                  toItem:self.label attribute:NSLayoutAttributeTrailing

                  multiplier:1.0f constant:self.labelValueGap];

    constraint.priority = UILayoutPriorityDefaultHigh + 1;

    [self.labelValueConstraints addObject:constraint];

    self.labelToValueHorizConstraint = constraint;





    constraint = [NSLayoutConstraint

                  constraintWithItem:self.label attribute:NSLayoutAttributeBaseline

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.valueView attribute:NSLayoutAttributeBaseline

                  multiplier:1.0f constant:0.f];

    constraint.priority = 600;

    [self.labelValueConstraints addObject:constraint];





    constraint = [NSLayoutConstraint

                  constraintWithItem:self.valueView attribute:NSLayoutAttributeWidth

                  relatedBy:NSLayoutRelationEqual

                  toItem:self.view attribute:NSLayoutAttributeWidth

                  multiplier:(1.f - self.labelWidthPercentage) constant:0];

    constraint.priority = 305;

    [self.labelValueConstraints addObject:constraint];

    self.valueWidthConstraint = constraint;





    [self setCompressionAndHuggingForLabelView:self.label];

    [self setCompressionAndHuggingForValueView:self.valueView];

}



- (void)setCompressionAndHuggingForLabelView:(UILabel *)labelView {

    if (!labelView) {

        return;

    }

    [labelView setContentCompressionResistancePriority:510 forAxis:UILayoutConstraintAxisHorizontal];

    [labelView setContentCompressionResistancePriority:UILayoutPriorityDefaultHigh forAxis:UILayoutConstraintAxisVertical];

    [labelView setContentHuggingPriority:450 forAxis:UILayoutConstraintAxisHorizontal];

    [labelView setContentHuggingPriority:UILayoutPriorityDefaultHigh forAxis:UILayoutConstraintAxisVertical];

}



- (void)setCompressionAndHuggingForValueView:(UIView *)valueView {

    if (!valueView) {

        return;

    }

    [valueView setContentCompressionResistancePriority:509 forAxis:UILayoutConstraintAxisHorizontal];

    [valueView setContentCompressionResistancePriority:UILayoutPriorityDefaultHigh forAxis:UILayoutConstraintAxisVertical];

    [valueView setContentHuggingPriority:300 forAxis:UILayoutConstraintAxisHorizontal];

    [valueView setContentHuggingPriority:650 forAxis:UILayoutConstraintAxisVertical];

}



/****** END Individual Field Controller ******/