无法使用UILabel进行自动换行

Question

我已经使用Interface Builder来获取UILabelViews进行自动换行，但这是我第一次尝试以编程方式进行。我认为问题是，虽然我设置：

label.lineBreakMode = .byWordWrapping 
label.numberOfLines = 0 

我设置行高可能与这些属性相冲突？

override func layoutSubviews() { 
    super.layoutSubviews() 
    imageViewContent.frame = CGRect(x: 0, y: 0, width: frame.size.width, height: frame.size.height) 
    imageViewContent.loadImageWithURL(imageName!) 

    label.frame = CGRect(x: 0, y: 0, width: frame.size.width-10, height: 21) 
    label.center = imageViewContent.center 
    label.textAlignment = .center 
    label.clipsToBounds = true 
    label.layer.cornerRadius = 10.0 
    label.textColor = .white 
    label.font = UIFont(name: "AvenirNext-DemiBold", size: 15) 
    label.backgroundColor = UIColor.black.withAlphaComponent(0.5) 
    label.lineBreakMode = .byWordWrapping 
    label.numberOfLines = 0 
    label.text = photoName 
} 

Answer 1

正如我怀疑，硬编码标签的高度阻止它的文字包装。我创建了一个labelHeight变量，并在该类的底部添加了一个函数，以根据我设置的内容，字体大小和labelWidth计算labelHeight。代码现在正常工作：

class NTWaterfallViewCell :UICollectionViewCell, NTTansitionWaterfallGridViewProtocol{ 

     var photoName = "" 
     var imageName : String? 
     var labelHeight: CGFloat = 0.0 

     var imageViewContent : UIImageView = UIImageView() 
     var label = UILabel() 

     required init?(coder aDecoder: NSCoder) { 
      fatalError("init(coder:) has not been implemented") 
     } 
     override init(frame: CGRect) { 
      super.init(frame: frame) 
      backgroundColor = UIColor.lightGray 
      contentView.addSubview(imageViewContent) 
      contentView.addSubview(label) 
     } 
     override func layoutSubviews() { 
      super.layoutSubviews() 
      imageViewContent.frame = CGRect(x: 0, y: 0, width: frame.size.width, height: frame.size.height) 
      imageViewContent.loadImageWithURL(imageName!) 

      label.text = photoName 
      labelHeight = heightForText(photoName, width: frame.size.width-10) 
      label.frame = CGRect(x: 0, y: 0, width: frame.size.width-10, height: labelHeight) 

      label.center = imageViewContent.center 
      label.textAlignment = .center 
      label.clipsToBounds = true 
      label.layer.cornerRadius = 10.0 
      label.textColor = .white 
      label.font = UIFont(name: "AvenirNext-DemiBold", size: 15) 
      label.backgroundColor = UIColor.black.withAlphaComponent(0.5) 
      label.lineBreakMode = .byWordWrapping 
      label.numberOfLines = 0 
      } 

     func heightForText(_ text: String, width: CGFloat) -> CGFloat { 
      let font = UIFont(name: "AvenirNext-DemiBold", size: 15) 
      let rect = NSString(string: text).boundingRect(with: CGSize(width: width, height: CGFloat(MAXFLOAT)), options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil) 
      return ceil(rect.height) 
     } 
}