Question

UITableViewCell包含UIImageView，其高度为UITableViewAutomaticDimension。

我想根据图像大小调整图像视图的大小。然后，图像视图应调整表格视图单元格的高度。

Interface Builder中图像视图的垂直布局约束是：

imageView.topAnchor = cell.contentView.topAnchor
imageView.bottomAnchor＆lt; = cell.contentView.bottomAnchor + 10
imageView.heightAnchor = 100

我已将布局约束设置为图像视图的高度锚点的IBOutlet。一旦我改变其常量，布局就会中断并忽略约束。表格视图单元格的高度不适应其大小，似乎打破了约束。

约束常量在：

处更改

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier) as! MyCell
    cell.image = image
    cell.updateConstraint()
    return cell
}

class MyCell {

    func updateConstraint() {
        imageViewHeightConstraint.constant = image.size.height // This line already throws the UIViewAlertForUnsatisfiableConstraints exception
        imageImageView.setNeedsLayout()
    }
}

如何正确完成？

更新错误日志打破了＆＃34; width = height＆＃34;约束因为布局实际上比上面描述的要复杂一点：widthAnchors＆＃39;常量被更改，图像视图的widthAnchor = heightAnchor。

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:0x7f98be1a22b0 H:[UIImageView:0x7f98be7d36e0(96)]>",
    "<NSLayoutConstraint:0x7f98be158470 UIImageView:0x7f98be7d36e0.width == UIImageView:0x7f98be7d36e0.height>",
    "<NSLayoutConstraint:0x7f98be1273e0 V:|-(5)-[UIImageView:0x7f98be7d36e0]   (Names: '|':UIView:0x7f98be12d860 )>",
    "<NSLayoutConstraint:0x7f98be133040 V:[UIImageView:0x7f98be7d36e0]-(5)-|   (Names: '|':UIView:0x7f98be12d860 )>",
    "<NSLayoutConstraint:0x7f98be1929e0 V:|-(5)-[UIView:0x7f98be12d860]   (Names: '|':UITableViewCellContentView:0x7f98be1582f0 )>",
    "<NSLayoutConstraint:0x7f98be12dd10 V:[UIView:0x7f98be12d860]-(>=10)-|   (Names: '|':UITableViewCellContentView:0x7f98be1582f0 )>",
    "<NSLayoutConstraint:0x7f98be7d66a0 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x7f98be1582f0(89)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7f98be158470 UIImageView:0x7f98be7d36e0.width == UIImageView:0x7f98be7d36e0.height>

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.

如何在动态高度的UITableViewCell中更新NSLayoutConstraint？

0 个答案: