UITableViewCell子类的奇怪布局约束

时间：2015-02-23 16:33:20

标签： ios objective-c iphone uitableview autolayout

我刚刚遇到一个关于奇怪的UITableViewCell子类布局的奇怪问题。 我在代码中配置了所有这些东西的UITableViewCell子类。

  • iPhone 5s及以下完美工作

enter image description here

  • iPhone 6或以上 错误：（

enter image description here

我确信这是子类问题。 

(lldb) po _tableView
<UITableView: 0x7fa5db054c00; frame = (0 0; 375 618); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x7fa5d96649e0>; layer = <CALayer: 0x7fa5d96632a0>; contentOffset: {0, 0}; contentSize: {375, 15552}>

代码： 

@interface ColorCell : UITableViewCell

@end 

@implementation ColorCell

- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
    self.background  = [UIView new];
    self.top         = [UIView new];
    self.bottom      = [UIView new];

    self.contentView.translatesAutoresizingMaskIntoConstraints = NO;
    self.background.translatesAutoresizingMaskIntoConstraints  = NO;
    self.top.       translatesAutoresizingMaskIntoConstraints  = NO;
    self.bottom.    translatesAutoresizingMaskIntoConstraints  = NO;

    [self.contentView addSubview:self.background];
    [self.background addSubview:self.top];
    [self.background addSubview:self.bottom];

    self.top.backgroundColor        = [UIColor purpleColor];
    self.bottom.backgroundColor     = [UIColor blackColor];

  }
  return self;
}

- (void)updateConstraints
{
    [super updateConstraints];
    if (!self.didSetupConstraints) {

    NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(_firstColor,_secondColor,_thirdColor,_fourthColor,_fifthColor,_background,_top,_bottom,_title,_stars,_favourites);

    NSString *format;
    NSArray *constraintsArray;
    NSDictionary *metrics = @{@"topHeight":@100.0, @"bottomHeight":@50};

    format = @"V:|[_background]|";
    constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:NSLayoutFormatAlignAllCenterX metrics:nil views:viewsDictionary];
    [self.contentView addConstraints:constraintsArray];

    format = @"H:|[_background]|";
    constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:NSLayoutFormatAlignAllCenterX metrics:nil views:viewsDictionary];
    [self.contentView addConstraints:constraintsArray];

    format = @"V:|[_top(topHeight)][_bottom(bottomHeight)]|";
    constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:0 metrics:metrics views:viewsDictionary];
    [_background addConstraints:constraintsArray];

    format = @"H:|[_bottom]|";
    constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
    [_background addConstraints:constraintsArray];

    format = @"H:|[_top]|";
    constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
    [_background addConstraints:constraintsArray];

    self.didSetupConstraints = YES;
  }
}

感谢。

修改 

(lldb) po [[UIWindow keyWindow] recursiveDescription]
<UIWindow: 0x7fa91341ce00; frame = (0 0; 375 667); gestureRecognizers = <NSArray: 0x7fa91341b290>; layer = <UIWindowLayer: 0x7fa91341c610>>
| <UILayoutContainerView: 0x7fa913703e70; frame = (0 0; 375 667); autoresize = W+H; gestureRecognizers = <NSArray: 0x7fa91343f400>; layer = <CALayer: 0x7fa913702480>>
|    | <UINavigationTransitionView: 0x7fa913621e80; frame = (0 0; 375 667); clipsToBounds = YES; autoresize = W+H; layer = <CALayer: 0x7fa91361d7e0>>
|    |    | <UIViewControllerWrapperView: 0x7fa9159678d0; frame = (0 0; 375 667); autoresize = W+H; layer = <CALayer: 0x7fa91343f150>>
|    |    |    | <UIView: 0x7fa913441190; frame = (0 0; 375 667); autoresize = W+H; layer = <CALayer: 0x7fa913443820>>
|    |    |    |    | <UITableView: 0x7fa913841400; frame = (0 0; 375 618); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x7fa91342f520>; layer = <CALayer: 0x7fa913435060>; contentOffset: {0, 0}; contentSize: {375, 15582}>
|    |    |    |    |    | <UITableViewWrapperView: 0x7fa913445200; frame = (0 0; 375 618); gestureRecognizers = <NSArray: 0x7fa913440320>; layer = <CALayer: 0x7fa9134319d0>; contentOffset: {0, 0}; contentSize: {375, 618}>
|    |    |    |    |    |    | <ColorCell: 0x7fa913637230; baseClass = UITableViewCell; frame = (0 600; 375 150); autoresize = W; layer = <CALayer: 0x7fa9136375b0>>
|    |    |    |    |    |    |    | <UITableViewCellContentView: 0x7fa913637630; frame = (0 0; 375 150); gestureRecognizers = <NSArray: 0x7fa913637960>; layer = <CALayer: 0x7fa913637700>>
|    |    |    |    |    |    |    |    | <UIView: 0x7fa9136379c0; frame = (0 0; 324 150); layer = <CALayer: 0x7fa913637a90>>
|    |    |    |    |    |    |    |    |    | <UIView: 0x7fa913638730; frame = (0 0; 324 100); layer = <CALayer: 0x7fa913638800>>
|    |    |    |    |    |    |    |    |    |    | <UIView: 0x7fa913637ab0; frame = (0 0; 0 0); layer = <CALayer: 0x7fa913637b80>>
|    |    |    |    |    |    |    |    |    |    | <UIView: 0x7fa913637ba0; frame = (0 0; 0 0); layer = <CALayer: 0x7fa913637c70>>
|    |    |    |    |    |    |    |    |    |    | <UIView: 0x7fa913637c90; frame = (0 0; 0 0); layer = <CALayer: 0x7fa913637d60>>
|    |    |    |    |    |    |    |    |    |    | <UIView: 0x7fa913637d80; frame = (0 0; 0 0); layer = <CALayer: 0x7fa913637e50>>
|    |    |    |    |    |    |    |    |    |    | <UIView: 0x7fa913637e70; frame = (0 0; 0 0); layer = <CALayer: 0x7fa913637f40>>
|    |    |    |    |    |    |    |    |    | <UIView: 0x7fa913638820; frame = (0 100; 324 50); layer = <CALayer: 0x7fa9136388f0>>
|    |    |    |    |    |    |    |    |    |    | <UILabel: 0x7fa913637f60; frame = (8 8; 240 34); userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7fa913636920>>
|    |    |    |    |    |    |    |    |    |    |    | <_UILabelContentLayer: 0x7fa9135b5ba0> (layer)
|    |    |    |    |    |    |    |    |    |    | <UIImageView: 0x7fa913638290; frame = (256 25; 17 0); userInteractionEnabled = NO; layer = <CALayer: 0x7fa913638390>>
|    |    |    |    |    |    |    |    |    |    | <UILabel: 0x7fa9136383b0; frame = (281 -100; 35 0); clipsToBounds = YES; userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7fa913638510>>

奇怪点： 如果我删除了self.contentView.translatesAutoresizingMaskIntoConstraints = NO，那就完美了。但奇怪的问题是对提出的限制的警告。 

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. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
  "<NSLayoutConstraint:0x7fad5b9764e0 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x7fad5b971a20(44)]>",
  "<NSLayoutConstraint:0x7fad5b976fb0 V:|-(0)-[UIView:0x7fad5b971db0]   (Names: '|':UITableViewCellContentView:0x7fad5b971a20 )>",
  "<NSLayoutConstraint:0x7fad5b976db0 V:[UIView:0x7fad5b971db0]-(0)-|   (Names: '|':UITableViewCellContentView:0x7fad5b971a20 )>",
  "<NSLayoutConstraint:0x7fad5b9763c0 V:|-(0)-[UIView:0x7fad5b972b70]   (Names: '|':UIView:0x7fad5b971db0 )>",
  "<NSLayoutConstraint:0x7fad5b977730 V:[UIView:0x7fad5b972b70(100)]>",
  "<NSLayoutConstraint:0x7fad5b976410 V:[UIView:0x7fad5b972b70]-(0)-[UIView:0x7fad5b972c60]>",
  "<NSLayoutConstraint:0x7fad5b9777b0 V:[UIView:0x7fad5b972c60(50)]>",
  "<NSLayoutConstraint:0x7fad5b977800 V:[UIView:0x7fad5b972c60]-(0)-|   (Names: '|':UIView:0x7fad5b971db0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7fad5b976410 V:[UIView:0x7fad5b972b70]-(0)-[UIView:0x7fad5b972c60]>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

2 个答案:

答案 0 :(得分：4)

您不应该self.contentView.translatesAutoresizingMaskIntoConstraints = NO;，因为这不是以编程方式创建的。此外，您需要在覆盖的END处调用[super updateConstraints]，而不是在开头。

编辑包含错误（来自下面的评论）：这里发生的是UIView-Encapsulated-Layout-Height是为自定义单元格创建的iOS 8约束。创建单元格后，如果修改了约束，您将收到此错误。有几种方法可以管理它;在这种情况下，我还是要提一下，因为你只需要一次添加约束，尝试添加不在updateConstraints中但在initWithStyle中的约束：reuseIdentifier。

问题更加微妙，iOS 8出现了一个新问题：在某些时候你的tableView认为行高是44，所以它创建了一个约束，设置单元格高度为44.然后你添加这些约束，但是tableView不会重新计算高度，因此您会收到错误。如果像@Rob上面提到的那样，你将把高度设置为44就可以了。它不会解决你的问题是一些约束告诉tableView高度应该是44，但无论你怎么能将estimatedRowHeight设置为150，因为这看起来像一个安全的估计，或者如果它们肯定都将是150只将rowHeight设置为该值。

答案 1 :(得分：1)

我终于找出了约束警告的原因。

我删除了- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath委托方法，警告消失了。

所以答案很明确：我不应该对heightForRowAtIndexPath中的约束更新做些什么。相反，我只返回rowHeight，然后修复了问题。

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