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我有一个 UILabel
,在某些情况下文本比 UILabel
本身长,所以我看到的文本是 "bla bla bla... "
我想在 UILabel
的末尾添加一个 ...Read More
按钮文本..
我读过一些帖子,但它们提供的解决方案对我来说并不好,例如:计算将输入 UILabel
的字符数,但我使用的是每个字符的字体具有不同的宽度。
我怎样才能做到这一点?
提前致谢!
最佳答案
Swift4(iOS 11.2)
Readmore at the end of the label without action
extension UILabel {
func addTrailing(with trailingText: String, moreText: String, moreTextFont: UIFont, moreTextColor: UIColor) {
let readMoreText: String = trailingText + moreText
let lengthForVisibleString: Int = self.visibleTextLength
let mutableString: String = self.text!
let trimmedString: String? = (mutableString as NSString).replacingCharacters(in: NSRange(location: lengthForVisibleString, length: ((self.text?.count)! - lengthForVisibleString)), with: "")
let readMoreLength: Int = (readMoreText.count)
let trimmedForReadMore: String = (trimmedString! as NSString).replacingCharacters(in: NSRange(location: ((trimmedString?.count ?? 0) - readMoreLength), length: readMoreLength), with: "") + trailingText
let answerAttributed = NSMutableAttributedString(string: trimmedForReadMore, attributes: [NSAttributedStringKey.font: self.font])
let readMoreAttributed = NSMutableAttributedString(string: moreText, attributes: [NSAttributedStringKey.font: moreTextFont, NSAttributedStringKey.foregroundColor: moreTextColor])
answerAttributed.append(readMoreAttributed)
self.attributedText = answerAttributed
}
var visibleTextLength: Int {
let font: UIFont = self.font
let mode: NSLineBreakMode = self.lineBreakMode
let labelWidth: CGFloat = self.frame.size.width
let labelHeight: CGFloat = self.frame.size.height
let sizeConstraint = CGSize(width: labelWidth, height: CGFloat.greatestFiniteMagnitude)
let attributes: [AnyHashable: Any] = [NSAttributedStringKey.font: font]
let attributedText = NSAttributedString(string: self.text!, attributes: attributes as? [NSAttributedStringKey : Any])
let boundingRect: CGRect = attributedText.boundingRect(with: sizeConstraint, options: .usesLineFragmentOrigin, context: nil)
if boundingRect.size.height > labelHeight {
var index: Int = 0
var prev: Int = 0
let characterSet = CharacterSet.whitespacesAndNewlines
repeat {
prev = index
if mode == NSLineBreakMode.byCharWrapping {
index += 1
} else {
index = (self.text! as NSString).rangeOfCharacter(from: characterSet, options: [], range: NSRange(location: index + 1, length: self.text!.count - index - 1)).location
}
} while index != NSNotFound && index < self.text!.count && (self.text! as NSString).substring(to: index).boundingRect(with: sizeConstraint, options: .usesLineFragmentOrigin, attributes: attributes as? [NSAttributedStringKey : Any], context: nil).size.height <= labelHeight
return prev
}
return self.text!.count
}
}
swift 4.2
extension UILabel {
func addTrailing(with trailingText: String, moreText: String, moreTextFont: UIFont, moreTextColor: UIColor) {
let readMoreText: String = trailingText + moreText
let lengthForVisibleString: Int = self.vissibleTextLength
let mutableString: String = self.text!
let trimmedString: String? = (mutableString as NSString).replacingCharacters(in: NSRange(location: lengthForVisibleString, length: ((self.text?.count)! - lengthForVisibleString)), with: "")
let readMoreLength: Int = (readMoreText.count)
let trimmedForReadMore: String = (trimmedString! as NSString).replacingCharacters(in: NSRange(location: ((trimmedString?.count ?? 0) - readMoreLength), length: readMoreLength), with: "") + trailingText
let answerAttributed = NSMutableAttributedString(string: trimmedForReadMore, attributes: [NSAttributedString.Key.font: self.font])
let readMoreAttributed = NSMutableAttributedString(string: moreText, attributes: [NSAttributedString.Key.font: moreTextFont, NSAttributedString.Key.foregroundColor: moreTextColor])
answerAttributed.append(readMoreAttributed)
self.attributedText = answerAttributed
}
var vissibleTextLength: Int {
let font: UIFont = self.font
let mode: NSLineBreakMode = self.lineBreakMode
let labelWidth: CGFloat = self.frame.size.width
let labelHeight: CGFloat = self.frame.size.height
let sizeConstraint = CGSize(width: labelWidth, height: CGFloat.greatestFiniteMagnitude)
let attributes: [AnyHashable: Any] = [NSAttributedString.Key.font: font]
let attributedText = NSAttributedString(string: self.text!, attributes: attributes as? [NSAttributedString.Key : Any])
let boundingRect: CGRect = attributedText.boundingRect(with: sizeConstraint, options: .usesLineFragmentOrigin, context: nil)
if boundingRect.size.height > labelHeight {
var index: Int = 0
var prev: Int = 0
let characterSet = CharacterSet.whitespacesAndNewlines
repeat {
prev = index
if mode == NSLineBreakMode.byCharWrapping {
index += 1
} else {
index = (self.text! as NSString).rangeOfCharacter(from: characterSet, options: [], range: NSRange(location: index + 1, length: self.text!.count - index - 1)).location
}
} while index != NSNotFound && index < self.text!.count && (self.text! as NSString).substring(to: index).boundingRect(with: sizeConstraint, options: .usesLineFragmentOrigin, attributes: attributes as? [NSAttributedString.Key : Any], context: nil).size.height <= labelHeight
return prev
}
return self.text!.count
}
}
用法
let readmoreFont = UIFont(name: "Helvetica-Oblique", size: 11.0)
let readmoreFontColor = UIColor.blue
DispatchQueue.main.async {
self.yourLabel.addTrailing(with: "... ", moreText: "Readmore", moreTextFont: readmoreFont!, moreTextColor: readmoreFontColor)
}
结果
NOTE: - Action is not included for Readmore
关于ios - 将 "...Read More"添加到 UILabel 的末尾,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32309247/
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