找出基于Swift中的String的UILabel的大小

我正在尝试根据不同的string长度来计算UILabel的高度。

func calculateContentHeight() -> CGFloat{ var maxLabelSize: CGSize = CGSizeMake(frame.size.width - 48, CGFloat(9999)) var contentNSString = contentText as NSString var expectedLabelSize = contentNSString.boundingRectWithSize(maxLabelSize, options: NSStringDrawingOptions.UsesLineFragmentOrigin, attributes: [NSFontAttributeName: UIFont.systemFontOfSize(16.0)], context: nil) print("\(expectedLabelSize)") return expectedLabelSize.size.height } 

以上是我用来确定高度的当前function，但它不工作。 我将不胜感激任何帮助，我可以得到。 我会在Swift中而不是客观的C.

Answer 1

在String上使用扩展名

Swift 3

 extension String { func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat { let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude) let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil) return ceil(boundingBox.height) } func width(withConstraintedHeight height: CGFloat, font: UIFont) -> CGFloat { let constraintRect = CGSize(width: .greatestFiniteMagnitude, height: height) let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil) return ceil(boundingBox.width) } } 

也在NSAttributedString （这是非常有用的）

 extension NSAttributedString { func height(withConstrainedWidth width: CGFloat) -> CGFloat { let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude) let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil) return ceil(boundingBox.height) } func width(withConstrainedHeight height: CGFloat) -> CGFloat { let constraintRect = CGSize(width: .greatestFiniteMagnitude, height: height) let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil) return ceil(boundingBox.width) } } 

斯威夫特4

只需在extension String方法中更改attributes的值即可

从

 [NSFontAttributeName: font] 

至

 [.font : font] 

Answer 2

对于多行文本，此答案无法正常工作。 您可以使用UILabel构build不同的string扩展

 extension String { func height(constraintedWidth width: CGFloat, font: UIFont) -> CGFloat { let label = UILabel(frame: CGRect(x: 0, y: 0, width: width, height: .greatestFiniteMagnitude)) label.numberOfLines = 0 label.text = self label.font = font label.sizeToFit() return label.frame.height } } 

UILabel得到一个固定的宽度，并将.numberOfLines设置为0.通过添加文本并调用.sizeToFit（），它会自动调整到正确的高度。

代码是用Swift 3 written编写的