将匹配搜索字符串的字符串的一部分设为粗体

Question

我有一个项目表，每个项目都有一个标签。我还有一个搜索栏，用于根据是否mySearchBar.text为的子字符串来过滤表中的项目myLabel.text。

一切正常，但我想将与搜索字符串匹配的标签文本部分加粗。

最终产品将类似于Google Maps搜索。

Answer 1

斯威夫特4：XCode 9.x

private func filterAndModifyTextAttributes(searchStringCharacters: String, completeStringWithAttributedText: String) -> NSMutableAttributedString {

    let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: completeStringWithAttributedText)
    let pattern = searchStringCharacters.lowercased()
    let range: NSRange = NSMakeRange(0, completeStringWithAttributedText.characters.count)
    var regex = NSRegularExpression()
    do {
        regex = try NSRegularExpression(pattern: pattern, options: NSRegularExpression.Options())
        regex.enumerateMatches(in: completeStringWithAttributedText.lowercased(), options: NSRegularExpression.MatchingOptions(), range: range) {
            (textCheckingResult, matchingFlags, stop) in
            let subRange = textCheckingResult?.range
            let attributes : [NSAttributedStringKey : Any] = [.font : UIFont.boldSystemFont(ofSize: 17),.foregroundColor: UIColor.red ]
            attributedString.addAttributes(attributes, range: subRange!)
        }
    }catch{
        print(error.localizedDescription)
    }
    return attributedString
}

如何使用 ：

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
     let cell = UITableViewCell(style: .subtitle , reuseIdentifier: "Cell")
     cell.textLabel?.attributedText = self.filterAndModifyTextAttributes(searchStringCharacters: self.textFromSearchBar, completeStringWithAttributedText: searchResultString)
     return cell

}

Answer 2

这是我最终实现的示例：

@IBOutlet weak var mySearchBar: UISearchBar!
@IBOutlet weak var myLabel: UILabel!

...

func makeMatchingPartBold(searchText: String) {

    // check label text & search text
    guard
        let labelText = myLabel.text,
        let searchText = mySearchBar.text
    else {
        return
    }

    // bold attribute
    let boldAttr = [NSFontAttributeName: UIFont.boldSystemFont(ofSize: myLabel.font.pointSize)]

    // check if label text contains search text
    if let matchRange: Range = labelText.lowercased().range(of: searchText.lowercased()) {

        // get range start/length because NSMutableAttributedString.setAttributes() needs NSRange not Range<String.Index>
        let matchRangeStart: Int = labelText.distance(from: labelText.startIndex, to: matchRange.lowerBound)
        let matchRangeEnd: Int = labelText.distance(from: labelText.startIndex, to: matchRange.upperBound)
        let matchRangeLength: Int = matchRangeEnd - matchRangeStart

        // create mutable attributed string & bold matching part
        let newLabelText = NSMutableAttributedString(string: labelText)
        newLabelText.setAttributes(boldAttr, range: NSMakeRange(matchRangeStart, matchRangeLength))

        // set label attributed text
        myLabel.attributedText = newNameText
    }
}