我试图计算基于不同字符串长度的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
}
上面是我用来确定高度的当前函数，但它不起作用。如果能得到任何帮助，我将不胜感激。我更喜欢Swift的答案，而不是Objective C。
我发现公认的答案适用于固定的宽度，但不适用于固定的高度。对于固定的高度，它只会增加宽度以适应一行中的所有内容，除非文本中有换行符。
width函数多次调用height函数，但这是一个快速计算，在UITable的行中使用该函数时，我没有注意到性能问题。
extension String {
public func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [.font : font], context: nil)
return ceil(boundingBox.height)
}
public func width(withConstrainedHeight height: CGFloat, font: UIFont, minimumTextWrapWidth:CGFloat) -> CGFloat {
var textWidth:CGFloat = minimumTextWrapWidth
let incrementWidth:CGFloat = minimumTextWrapWidth * 0.1
var textHeight:CGFloat = self.height(withConstrainedWidth: textWidth, font: font)
//Increase width by 10% of minimumTextWrapWidth until minimum width found that makes the text fit within the specified height
while textHeight > height {
textWidth += incrementWidth
textHeight = self.height(withConstrainedWidth: textWidth, font: font)
}
return ceil(textWidth)
}
}
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)
}
}
在String上使用扩展
斯威夫特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(withConstrainedHeight 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)
}
}
还有NSAttributedString(有时非常有用)
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)
}
}
Swift 4 & 5
只需更改扩展String方法中的属性值
from
[NSFontAttributeName: font]
to
[.font : font]
这里有一个简单的解决方案，对我来说很有用。类似于其他发布的一些，但它不需要sizeToFit
注意这是用Swift 5写的
let lbl = UILabel()
lbl.numberOfLines = 0
lbl.font = UIFont.systemFont(ofSize: 12) // make sure you set this correctly
lbl.text = "My text that may or may not wrap lines..."
let width = 100.0 // the width of the view you are constraint to, keep in mind any applied margins here
let height = lbl.systemLayoutSizeFitting(CGSize(width: width, height: UIView.layoutFittingCompressedSize.height), withHorizontalFittingPriority: .required, verticalFittingPriority: .fittingSizeLevel).height
它处理行换行等。不是最优雅的代码，但它完成了工作。
