iOS Swift 以编程方式更改标签内的特定文本颜色

Question

我的应用程序中有一些搜索选项，它会突出显示 UISearchBar 中的给定单词。给定的词可能在标签中出现多次，我不需要突出显示所有这些词。这怎么可能，我尝试了一些代码，但它只会突出显示该词的一次出现，这是我的示例代码:

var SearchAttributeText = "The"
let range = (TextValue as NSString).range(of: SearchAttributeText)
let attribute = NSMutableAttributedString.init(string: TextValue)
attribute.addAttribute(NSForegroundColorAttributeName, value: UIColor.red , range: range)
self.label.attributedText = attribute

需要支持 Upper 和 lower 两种情况。单词可能会出现多次，需要全部高亮。

Answer 1

您可以使用以下代码在字符串中搜索

    //Text need to be searched
    let SearchAttributeText = "the"

    //Store label text in variable as NSString
    let contentString = lblContent.text! as NSString

    //Create range of label text
    var rangeString = NSMakeRange(0, contentString.length)

    //Convert label text into attributed string
    let attribute = NSMutableAttributedString.init(string: contentString as String)

    while (rangeString.length != NSNotFound && rangeString.location != NSNotFound) {

        //Get the range of search text
        let colorRange = (lblContent.text?.lowercased() as! NSString).range(of: SearchAttributeText, options: NSString.CompareOptions(rawValue: 0), range: rangeString)

        if (colorRange.location == NSNotFound) {
            //If location is not present in the string the loop will break
            break
        } else {
            //This line of code colour the searched text
            attribute.addAttribute(NSAttributedStringKey.foregroundColor, value: UIColor.red , range: colorRange)
            lblContent.attributedText = attribute

            //This line of code increment the rangeString variable
            rangeString = NSMakeRange(colorRange.location + colorRange.length, contentString.length - (colorRange.location + colorRange.length))
        }
    }

下面的代码行通过增加 NSRange 的 location 和 length 参数来更新范围

rangeString = NSMakeRange(colorRange.location + colorRange.length, contentString.length - (colorRange.location + colorRange.length))