UITableViewCell通过内容拥抱自动调整大小

Firstly, set the trailing constraint on your label to be >=20. This lets the label shrink.

Your real problem though is this method:

- (void)setBounds:(CGRect)bounds {
    [super setBounds:bounds];

    if (self.numberOfLines == 0 && bounds.size.width != self.preferredMaxLayoutWidth) {
        self.preferredMaxLayoutWidth = self.bounds.size.width;
        [self setNeedsUpdateConstraints];
    }
}

You would be better to set cell.theLabel.preferedMaxLayoutWidth when you create the cell in both heightForRowAtIndexPath and cellForRowAtIndexPath.

If you comment this code out completely it all seems to work.

You can also make your code work if you create a new prototype cell every time heightForRowAtIndexPath is called. This is what led me to the above function.

It seems that every time heightForRowAtIndexPath is called, the reuse of the prototype cell results in a combinatorial increase in height. You see this if you scroll down and back up.

So I would remove this method completely and let the constraints do the work for you. I see the cells shrink when one line to exact size and everything else compact.

Before you set the text in createCellForRowAtIndexPath add the following to make the layout width full screen minus your 20 margins:

cell.messageLabel.preferredMaxLayoutWidth=self.view.bounds.size.width-40;

and before you set the text in the prototype cells in heightForRowAtIndexPath:

prototypeCell.messageLabel.preferredMaxLayoutWidth=self.view.bounds.size.width-40;

设置preferredMaxLayoutWidth会导致旋转问题。设置每个单元格意味着每个单元格现在都具有特定于方向的约束。为了解决这个问题，您必须通过将以下内容添加到视图控制器中来在旋转时重新加载表：

- (void) willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
    [self.tableView reloadData];
}

最后结果：