在Swift中以粗体显示UILabel

2020/12/13 09:22 · ios ·  · 0评论

我有一个UILabel以编程方式制作的：

var label = UILabel()

然后，我为标签声明了一些样式，包括字体，例如：

label.frame = CGRect(x: 20, y: myHeaderView.frame.height / 2, width: 300, height: 30)
label.font = UIFont(name: "Typo GeoSlab Regular Demo", size: 15)
label.textColor = UIColor(hue: 0/360, saturation: 0/100, brightness: 91/100, alpha: 1)

标签的第一部分将始终显示为："Filter:"然后是字符串的另一部分，例如“ Most Popular”

我希望过滤器一词以粗体显示，所以整个过程看起来像：

筛选：最受欢迎

我想以最简单的方式来创建这种效果。我一直在互联网上寻找如何实现这一目标的方法，而且有很多方法，有些方法看起来像是代码页。而且大多数似乎在Objective-C中。我想要在Swift中:)

我不知道我是否正确，但这NSRange可以帮助您实现吗？提前致谢

更新资料

我使用一系列if语句来更改label变量。如：

if indexArray == 1 {

    label.text = "Filter: Film name"

} else if indexArray == 2 {

    label.text = "Filter: Most popular"

} else if indexArray == 3 {

    label.text = "Filter: Star rating"

}

您将需要使用attributedString它来设置字符串等的样式。可以通过具有两种样式（一种是普通样式，一种是粗体样式），然后将它们附加在一起来完成此操作：

let boldText = "Filter:"
let attrs = [NSAttributedString.Key.font : UIFont.boldSystemFont(ofSize: 15)]
let attributedString = NSMutableAttributedString(string:boldText, attributes:attrs)

let normalText = "Hi am normal"
let normalString = NSMutableAttributedString(string:normalText)

attributedString.append(normalString)

要将其分配给标签时：

label.attributedText = attributedString

您可以使用NSMutableAttributedString和NSAttributedString创建自定义字符串。下面的函数使给定的boldString在给定的字符串中加粗。

迅捷3

func attributedText(withString string: String, boldString: String, font: UIFont) -> NSAttributedString {
    let attributedString = NSMutableAttributedString(string: string,
                                                     attributes: [NSFontAttributeName: font])
    let boldFontAttribute: [String: Any] = [NSFontAttributeName: UIFont.boldSystemFont(ofSize: font.pointSize)]
    let range = (string as NSString).range(of: boldString)
    attributedString.addAttributes(boldFontAttribute, range: range)
    return attributedString
}

用法示例

authorLabel.attributedText = attributedText(withString: String(format: "Author : %@", user.name), boldString: "Author", font: authorLabel.font)

斯威夫特4

func attributedText(withString string: String, boldString: String, font: UIFont) -> NSAttributedString {
    let attributedString = NSMutableAttributedString(string: string,
                                                     attributes: [NSAttributedStringKey.font: font])
    let boldFontAttribute: [NSAttributedStringKey: Any] = [NSAttributedStringKey.font: UIFont.boldSystemFont(ofSize: font.pointSize)]
    let range = (string as NSString).range(of: boldString)
    attributedString.addAttributes(boldFontAttribute, range: range)
    return attributedString
}

Swift 4.2和5

func attributedText(withString string: String, boldString: String, font: UIFont) -> NSAttributedString {
    let attributedString = NSMutableAttributedString(string: string,
                                                 attributes: [NSAttributedString.Key.font: font])
    let boldFontAttribute: [NSAttributedString.Key: Any] = [NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: font.pointSize)]
    let range = (string as NSString).range(of: boldString)
    attributedString.addAttributes(boldFontAttribute, range: range)
    return attributedString
}

结果：

在此处输入图片说明

Swift 4.2和5.0：

首先，我们创建一个协议UILabel，UITextField并且UITextView可以采用。

public protocol ChangableFont: AnyObject {
    var rangedAttributes: [RangedAttributes] { get }
    func getText() -> String?
    func set(text: String?)
    func getAttributedText() -> NSAttributedString?
    func set(attributedText: NSAttributedString?)
    func getFont() -> UIFont?
    func changeFont(ofText text: String, with font: UIFont)
    func changeFont(inRange range: NSRange, with font: UIFont)
    func changeTextColor(ofText text: String, with color: UIColor)
    func changeTextColor(inRange range: NSRange, with color: UIColor)
    func resetFontChanges()
}

我们希望能够对文本添加多个更改，因此我们创建了rangedAttributes属性。这是一个自定义结构，其中包含属性及其应用范围。

public struct RangedAttributes {

    public let attributes: [NSAttributedString.Key: Any]
    public let range: NSRange

    public init(_ attributes: [NSAttributedString.Key: Any], inRange range: NSRange) {
        self.attributes = attributes
        self.range = range
    }
}

另一个问题是，UILabel它的font性能强劲，UITextField它的font属性是弱/可选。为了使它们都能与我们的ChangableFont协议一起使用，我们包括了该getFont() -> UIFont?方法。这也计数的UITextView它text和attributedText属性。这就是为什么我们也为它们实现getter和setter方法的原因。

extension UILabel: ChangableFont {

    public func getText() -> String? {
        return text
    }

    public func set(text: String?) {
        self.text = text
    }

    public func getAttributedText() -> NSAttributedString? {
        return attributedText
    }

    public func set(attributedText: NSAttributedString?) {
        self.attributedText = attributedText
    }

    public func getFont() -> UIFont? {
        return font
    }
}

extension UITextField: ChangableFont {

    public func getText() -> String? {
        return text
    }

    public func set(text: String?) {
        self.text = text
    }

    public func getAttributedText() -> NSAttributedString? {
        return attributedText
    }

    public func set(attributedText: NSAttributedString?) {
        self.attributedText = attributedText
    }

    public func getFont() -> UIFont? {
        return font
    }
}

extension UITextView: ChangableFont {

    public func getText() -> String? {
        return text
    }

    public func set(text: String?) {
        self.text = text
    }

    public func getAttributedText() -> NSAttributedString? {
        return attributedText
    }

    public func set(attributedText: NSAttributedString?) {
        self.attributedText = attributedText
    }

    public func getFont() -> UIFont? {
        return font
    }
}

现在，我们可以继续进行操作UILabel，UITextField并UITextView通过扩展协议来创建默认的实现。

public extension ChangableFont {

    var rangedAttributes: [RangedAttributes] {
        guard let attributedText = getAttributedText() else {
            return []
        }
        var rangedAttributes: [RangedAttributes] = []
        let fullRange = NSRange(
            location: 0,
            length: attributedText.string.count
        )
        attributedText.enumerateAttributes(
            in: fullRange,
            options: []
        ) { (attributes, range, stop) in
            guard range != fullRange, !attributes.isEmpty else { return }
            rangedAttributes.append(RangedAttributes(attributes, inRange: range))
        }
        return rangedAttributes
    }

    func changeFont(ofText text: String, with font: UIFont) {
        guard let range = (self.getAttributedText()?.string ?? self.getText())?.range(ofText: text) else { return }
        changeFont(inRange: range, with: font)
    }

    func changeFont(inRange range: NSRange, with font: UIFont) {
        add(attributes: [.font: font], inRange: range)
    }

    func changeTextColor(ofText text: String, with color: UIColor) {
        guard let range = (self.getAttributedText()?.string ?? self.getText())?.range(ofText: text) else { return }
        changeTextColor(inRange: range, with: color)
    }

    func changeTextColor(inRange range: NSRange, with color: UIColor) {
        add(attributes: [.foregroundColor: color], inRange: range)
    }

    private func add(attributes: [NSAttributedString.Key: Any], inRange range: NSRange) {
        guard !attributes.isEmpty else { return }

        var rangedAttributes: [RangedAttributes] = self.rangedAttributes

        var attributedString: NSMutableAttributedString

        if let attributedText = getAttributedText() {
            attributedString = NSMutableAttributedString(attributedString: attributedText)
        } else if let text = getText() {
            attributedString = NSMutableAttributedString(string: text)
        } else {
            return
        }

        rangedAttributes.append(RangedAttributes(attributes, inRange: range))

        rangedAttributes.forEach { (rangedAttributes) in
            attributedString.addAttributes(
                rangedAttributes.attributes,
                range: rangedAttributes.range
            )
        }

        set(attributedText: attributedString)
    }

    func resetFontChanges() {
        guard let text = getText() else { return }
        set(attributedText: NSMutableAttributedString(string: text))
    }
}

在默认实现我用得到一个小帮手方法NSRange的substring。

public extension String {

    func range(ofText text: String) -> NSRange {
        let fullText = self
        let range = (fullText as NSString).range(of: text)
        return range
    }
}

大功告成！现在，您可以更改部分文本的字体和文本颜色。

titleLabel.text = "Welcome"
titleLabel.font = UIFont.systemFont(ofSize: 70, weight: .bold)
titleLabel.textColor = UIColor.black
titleLabel.changeFont(ofText: "lc", with: UIFont.systemFont(ofSize: 60, weight: .light))
titleLabel.changeTextColor(ofText: "el", with: UIColor.blue)
titleLabel.changeTextColor(ofText: "co", with: UIColor.red)
titleLabel.changeTextColor(ofText: "m", with: UIColor.green)

Swift 4替代：

let attrs = [NSAttributedStringKey.font : UIFont.boldSystemFont(ofSize: 14)]
let attributedString = NSMutableAttributedString(string: "BOLD TEXT", attributes:attrs)
let normalString = NSMutableAttributedString(string: "normal text")
attributedString.append(normalString)
myLabel.attributedText = attributedString

只是分享我自己在Swift 4.0中非常灵活的实现。因为存在一些要求（例如当前的要求），所以您不仅需要设置粗体，还需要设置标签文本的斜体。

import UIKit

extension UILabel {

    /** Sets up the label with two different kinds of attributes in its attributed text.
     *  @params:
     *  - primaryString: the normal attributed string.
     *  - secondaryString: the bold or highlighted string.
     */

    func setAttributedText(primaryString: String, textColor: UIColor, font: UIFont, secondaryString: String, secondaryTextColor: UIColor, secondaryFont: UIFont) {

        let completeString = "\(primaryString) \(secondaryString)"

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .center

        let completeAttributedString = NSMutableAttributedString(
            string: completeString, attributes: [
                .font: font,
                .foregroundColor: textColor,
                .paragraphStyle: paragraphStyle
            ]
        )

        let secondStringAttribute: [NSAttributedStringKey: Any] = [
            .font: secondaryFont,
            .foregroundColor: secondaryTextColor,
            .paragraphStyle: paragraphStyle
        ]

        let range = (completeString as NSString).range(of: secondaryString)

        completeAttributedString.addAttributes(secondStringAttribute, range: range)

        self.attributedText = completeAttributedString
    }
}

如果愿意，可以直接在String上执行：

extension String {
func withBoldText(text: String, font: UIFont? = nil) -> NSAttributedString {
  let _font = font ?? UIFont.systemFont(ofSize: 14, weight: .regular)
  let fullString = NSMutableAttributedString(string: self, attributes: [NSAttributedString.Key.font: _font])
  let boldFontAttribute: [NSAttributedString.Key: Any] = [NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: _font.pointSize)]
  let range = (self as NSString).range(of: text)
  fullString.addAttributes(boldFontAttribute, range: range)
  return fullString
}}

用法：

label.attributeString = "my full string".withBoldText(text: "full")

对于那些喜欢扩展的人

斯威夫特5.0

    /// will set a regual and a bold text in the same label
    public func setRegualAndBoldText(regualText: String,
                                       boldiText: String) {

        let attrs = [NSAttributedString.Key.font : UIFont.boldSystemFont(ofSize: font.pointSize)]
        let regularString = NSMutableAttributedString(string: regualText)
        let boldiString = NSMutableAttributedString(string: boldiText, attributes:attrs)
        regularString.append(boldiString)
        attributedText = regularString
    }

并使用：

label.setRegualAndBoldText(regualText: "height: ", boldiText: "1.65 :(")

在此处输入图片说明

如果知道要加粗的字符位置值，我创建了一个函数，该函数接受字符范围和可选字体（如果只想使用大小为12的标准系统字体，则使用nil），并返回一个NSAttributedString，您可以将其附加标签作为其属性文本。我想加粗我的字符串的第0、10、22-23、30和34个字符，因此我使用了[[0,0]，[10,10]，[22,23]，[30,30]，[34 ，34]]设置为我的boldCharactersRanges值。

用法：

func boldenParts(string: String, boldCharactersRanges: [[Int]], regularFont: UIFont?, boldFont: UIFont?) -> NSAttributedString {
    let attributedString = NSMutableAttributedString(string: string, attributes: [NSAttributedString.Key.font: regularFont ?? UIFont.systemFont(ofSize: 12)])
    let boldFontAttribute: [NSAttributedString.Key: Any] = [NSAttributedString.Key.font: boldFont ?? UIFont.boldSystemFont(ofSize: regularFont?.pointSize ?? UIFont.systemFontSize)]
    for range in boldCharactersRanges {
        let currentRange = NSRange(location: range[0], length: range[1]-range[0]+1)
        attributedString.addAttributes(boldFontAttribute, range: currentRange)
        }
    return attributedString
}

override func viewDidLoad() {
    super.viewDidLoad()
    let label = UILabel()
    label.frame = CGRect(x: 0, y: 0, width: 180, height: 50)
    label.numberOfLines = 0
    label.center = view.center
    let text = "Under the pillow is a vogue article"
    let secretMessage = boldenParts(string: text, boldCharactersRanges: [[0,0], [10,10], [22,23], [30,30], [34,34]], regularFont: UIFont(name: "Avenir", size: 15), boldFont: UIFont(name: "Avenir-Black", size: 15))
    label.attributedText = secretMessage
    view.addSubview(label)
}

Swift 4.0解决方案

let font = UIFont.systemFont(ofSize: 14)

func boldSearchResult(searchString: String, resultString: String) -> NSMutableAttributedString {
    let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: resultString)

    guard let regex  = try? NSRegularExpression(pattern: searchString.lowercased(), options: []) else {
        return attributedString
    }

    let range: NSRange = NSMakeRange(0, resultString.count)

    regex.enumerateMatches(in: resultString.lowercased(), options: [], range: range) { (textCheckingResult, matchingFlags, stop) in
        guard let subRange = textCheckingResult?.range else {
            return
        }

        attributedString.addAttributes([NSAttributedString.Key.font : font], range: subRange)
    }

    return attributedString
}
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