具有动态高度 UILabel 和 UIView（容器）的表格单元格内的自动布局问题

Question

我正在使用具有自动布局的动态高度表格单元格，在表格单元格内部，有 1 个动态高度 UILabel 和 1 个动态 UIView，其中包含多个 UIImageView。

这是布局： Storyboard screenshot

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
     tableView.estimatedRowHeight = 500;
    return UITableViewAutomaticDimension;
}

表格单元：

for(i=0; i<subviews.count; i++)

    UIImageView *imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"ic_image.png"]];

    [imgView setContentMode:UIViewContentModeScaleAspectFill];
    imgView.clipsToBounds = YES;

    [_viewAttaches addSubview:imgView];
    imgView.translatesAutoresizingMaskIntoConstraints = NO;

    if(i==0) {
        NSLayoutConstraint *top = [NSLayoutConstraint
                                       constraintWithItem:imgView
                                       attribute:NSLayoutAttributeTop
                                       relatedBy:NSLayoutRelationEqual
                                       toItem:_viewAttaches
                                       attribute:NSLayoutAttributeTop
                                       multiplier:1.0f
                                       constant:0.f];
        [_viewAttaches addConstraint:top];
     } else {
             UIImageView *prevView = subviews[i-1];
             NSLayoutConstraint *top = [NSLayoutConstraint
                                               constraintWithItem:imgView
                                               attribute:NSLayoutAttributeTop
                                               relatedBy:NSLayoutRelationEqual
                                               toItem:prevView
                                               attribute:NSLayoutAttributeBottom
                                               multiplier:1.0f
                                               constant:10.f];
              [_viewAttaches addConstraint:top];
           }

           NSLayoutConstraint *leading = [NSLayoutConstraint
                                               constraintWithItem:imgView
                                               attribute:NSLayoutAttributeLeading
                                               relatedBy:NSLayoutRelationEqual
                                               toItem:_viewAttaches
                                               attribute:NSLayoutAttributeLeading
                                               multiplier:1.0f
                                               constant:0.f];

            [_viewAttaches addConstraint:leading];

            NSLayoutConstraint *trailing = [NSLayoutConstraint
                                                constraintWithItem:imgView
                                                attribute:NSLayoutAttributeTrailing
                                                relatedBy:NSLayoutRelationEqual
                                                toItem:_viewAttaches
                                                attribute:NSLayoutAttributeTrailing
                                                multiplier:1.0f
                                                constant:0.f];

            [_viewAttaches addConstraint:trailing];


            NSLayoutConstraint *height = [NSLayoutConstraint constraintWithItem:imgView
                                                                              attribute:NSLayoutAttributeHeight
                                                                              relatedBy:NSLayoutRelationEqual
                                                                                 toItem:nil
                                                                              attribute:NSLayoutAttributeNotAnAttribute
                                                                             multiplier:1
                                                                               constant:160];
            [_viewAttaches addConstraint:height];


                if(i==nAttaches-1) {
                    NSLayoutConstraint *bottom = [NSLayoutConstraint
                                                  constraintWithItem:imgView
                                                  attribute:NSLayoutAttributeBottom
                                                  relatedBy:NSLayoutRelationEqual
                                                  toItem:_viewAttaches
                                                  attribute:NSLayoutAttributeBottom
                                                  multiplier:1.0f
                                                  constant:0.f];
                    [_viewAttaches addConstraint:bottom];
                }

                i++;
}

但是我收到了这个错误：

[LayoutConstraints] 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:0x174288390 UILabel:0x101157580'Daniel'.height == 21   (active)>,
"<NSLayoutConstraint:0x174288cf0 UILabel:0x101158cb0'0 comments'.height == 21   (active)>",
"<NSLayoutConstraint:0x174288e80 UILabel:0x101157580'Daniel'.top == UITableViewCellContentView:0x101157130.topMargin + 2   (active)>",
"<NSLayoutConstraint:0x174288fc0 V:[UILabel:0x101157580'Daniel']-(-1)-[UILabel:0x1011469b0'I am currently in a happy...']   (active)>",
"<NSLayoutConstraint:0x1742890b0 V:[UILabel:0x1011469b0'I am currently in a happy...']-(0)-[UIView:0x101158b10]   (active)>",
"<NSLayoutConstraint:0x174289240 V:[UIView:0x101158b10]-(-1)-[UILabel:0x101158cb0'0 comments']   (active)>",
"<NSLayoutConstraint:0x1742892e0 UITableViewCellContentView:0x101157130.bottomMargin == UILabel:0x101158cb0'0 comments'.bottom + 1   (active)>",
"<NSLayoutConstraint:0x170284ec0 UIView:0x101158b10.height == 330   (active)>",
"<NSLayoutConstraint:0x17428a640 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x101157130.height == 89   (active)>"


Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x170284ec0 UIView:0x101158b10.height == 330   (active)>

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.

请帮我解决我所缺少的。提前谢谢你。

Answer 1

您所做的工作几乎是正确的，请保持以下更改以解决此问题

1. 更改UITableviewCell 中的视图层次结构并在下面创建如下 .

-> Timeline TableView
  '-> postecell
     '-> content view
        '-> myView // I added this `UIview` & in this view add all you cell components
          '-> Img User
          '-> lbl Name
          :    :
          :    :

myView 约束：

1. 顶部、底部、前导、跟踪到超级视图。

   编辑 - 删除下面的行

   1. 身高与关系greater than equal to (≥)

注意：确保单元格中的每个组件都必须有上下关系和固定高度，关系=，动态标签关系≥。

2.你的身高代码是这样的

- (CGFloat)tableView:(UITableView *)tableView    estimatedHeightForRowAtIndexPath:(NSIndexPath *)indexPath {
     return 250; // it is the height of cell which is in the storyboard after creation of custom cell.
}   

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    return UITableViewAutomaticDimension; 
}

编辑

查看层次结构

故事板

输出：