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。
这是我在Swift 4.1和Xcode 9.4.1中的答案
//This is your label
let proNameLbl = UILabel(frame: CGRect(x: 0, y: 20, width: 300, height: height))
proNameLbl.text = "This is your text"
proNameLbl.font = UIFont.systemFont(ofSize: 17)
proNameLbl.numberOfLines = 0
proNameLbl.lineBreakMode = .byWordWrapping
infoView.addSubview(proNameLbl)
//Function to calculate height for label based on text
func heightForView(text:String, font:UIFont, width:CGFloat) -> CGFloat {
let label:UILabel = UILabel(frame: CGRect(x: 0, y: 0, width: width, height: CGFloat.greatestFiniteMagnitude))
label.numberOfLines = 0
label.lineBreakMode = NSLineBreakMode.byWordWrapping
label.font = font
label.text = text
label.sizeToFit()
return label.frame.height
}
现在你调用这个函数
//Call this function
let height = heightForView(text: "This is your text", font: UIFont.systemFont(ofSize: 17), width: 300)
print(height)//Output : 41.0
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]
这个解决方案将有助于在运行时计算高度和宽度。
let messageText = "Your Text String"
let size = CGSize.init(width: 250, height: 1000)
let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
let estimateFrame = NSString(string: messageText).boundingRect(with: size, options: options, attributes: [NSAttributedString.Key.font: UIFont(name: "HelveticaNeue", size: 17)!], context: nil)
在这里,你可以计算你的字符串的估计高度,并将其传递给UILabel框架。
estimateFrame.Width
estimateFrame.Height
extension String{
func widthWithConstrainedHeight(_ height: CGFloat, font: UIFont) -> CGFloat {
let constraintRect = CGSize(width: CGFloat.greatestFiniteMagnitude, height: height)
let boundingBox = self.boundingRect(with: constraintRect, options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
return ceil(boundingBox.width)
}
func heightWithConstrainedWidth(_ width: CGFloat, font: UIFont) -> CGFloat? {
let constraintRect = CGSize(width: width, height: CGFloat.greatestFiniteMagnitude)
let boundingBox = self.boundingRect(with: constraintRect, options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
return ceil(boundingBox.height)
}
}