在c#中，这在UITableViewCell中为我工作。

        UILabel myLabel = new UILabel();
        myLabel.Font = UIFont.SystemFontOfSize(16);
        myLabel.Lines = 0;
        myLabel.TextAlignment = UITextAlignment.Left;
        myLabel.LineBreakMode = UILineBreakMode.WordWrap;
        myLabel.MinimumScaleFactor = 1;
        myLabel.AdjustsFontSizeToFitWidth = true;

       myLabel.InvalidateIntrinsicContentSize();
       myLabel.Frame = new CoreGraphics.CGRect(20, mycell.ContentView.Frame.Y + 20, cell.ContentView.Frame.Size.Width - 40, mycell.ContentView.Frame.Size.Height);
       myCell.ContentView.AddSubview(myLabel);

我认为这里的重点是:-

            myLabel.TextAlignment = UITextAlignment.Left;
            myLabel.LineBreakMode = UILineBreakMode.WordWrap;
            myLabel.MinimumScaleFactor = 1;
            myLabel.AdjustsFontSizeToFitWidth = true;

你应该试试这个:

-(CGFloat)dynamicLblHeight:(UILabel *)lbl
{
    CGFloat lblWidth = lbl.frame.size.width;
    CGRect lblTextSize = [lbl.text boundingRectWithSize:CGSizeMake(lblWidth, MAXFLOAT)
                                               options:NSStringDrawingUsesLineFragmentOrigin
                                            attributes:@{NSFontAttributeName:lbl.font}
                                               context:nil];
    return lblTextSize.size.height;
}

textLabel.lineBreakMode = UILineBreakModeWordWrap;
textLabel.numberOfLines = 0;

上面的解决方案对我的情况不起作用。我是这样做的:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // ...

    CGSize size = [str sizeWithFont:[UIFont fontWithName:@"Georgia-Bold" size:18.0] constrainedToSize:CGSizeMake(240.0, 480.0) lineBreakMode:UILineBreakModeWordWrap];
    return size.height + 20;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil)
    {
        // ...
        cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;
        cell.textLabel.numberOfLines = 0;
        cell.textLabel.font = [UIFont fontWithName:@"Georgia-Bold" size:18.0];
    }

    // ...

    UILabel *textLabel = [cell textLabel];
    CGSize size = [text sizeWithFont:[UIFont fontWithName:@"Georgia-Bold" size:18.0]
                                        constrainedToSize:CGSizeMake(240.0, 480.0)
                                            lineBreakMode:UILineBreakModeWordWrap];

    cell.textLabel.frame = CGRectMake(0, 0, size.width + 20, size.height + 20);

    //...
}

如果你必须使用:

myLabel.numberOfLines = 0;

属性，也可以在代码中使用标准换行符(“\n”)强制换行。

哦，在2021年，我被一个标签文本困住了，一个小时都不能换行，然后意识到我忘记设置标签的宽度，WTF。

let stepLabel: UILabel = {
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    label.textAlignment = .center
    label.lineBreakMode = .byWordWrapping
    label.numberOfLines = 0
    label.text = "Put your device and computer under same Wi-Fi network."
    
    return label
}()

override func viewDidLoad() {
    super.viewDidLoad()
    
    view.backgroundColor = .white
    view.addSubview(stepLabel)

    NSLayoutConstraint.activate([
        stepLabel.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        stepLabel.centerYAnchor.constraint(equalTo: view.centerYAnchor),
        stepLabel.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.7)
    ])
}

在下面的代码或故事板本身中设置

Label.lineBreakMode = NSLineBreakByWordWrapping; 标签行数 = 0;

请不要忘记为标签设置左、右、上、下约束，否则它将无法工作。