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)
    ])
}

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);

    //...
}

使用它在UILabel中有多行文本:

textLabel.lineBreakMode = NSLineBreakByWordWrapping;
textLabel.numberOfLines = 0;

迅速:

textLabel.lineBreakMode = .byWordWrapping
textLabel.numberOfLines = 0

在这个函数中，传递你想在label中赋值的字符串，并传递字体大小来代替self。activityFont和传递标签宽度的地方235，现在你得到标签高度根据你的字符串。 它会工作得很好。

-(float)calculateLabelStringHeight:(NSString *)answer
{
    CGRect textRect = [answer boundingRectWithSize: CGSizeMake(235, 10000000) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:self.activityFont} context:nil];
    return textRect.size.height;

}

我找到的最好的解决方案(解决一个本来应该在框架中解决的令人沮丧的问题)与vaychick的类似。

只需在IB或代码中将行数设置为0即可

myLabel.numberOfLines = 0;

这将显示所需的行，但将重新定位标签，使其水平居中(以便1行和3行标签在水平位置对齐)。要解决这个问题，添加:

CGRect currentFrame = myLabel.frame;
CGSize max = CGSizeMake(myLabel.frame.size.width, 500);
CGSize expected = [myString sizeWithFont:myLabel.font constrainedToSize:max lineBreakMode:myLabel.lineBreakMode]; 
currentFrame.size.height = expected.height;
myLabel.frame = currentFrame;

UILabel *textLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 150, 30)];
[textLabel sizeToFit];
textLabel.numberOfLines = 0;
textLabel.text = @"Your String...";