调整 NSMutableAttributedString 的字体大小与 UILabel 的框架高度成比例

Question

在我的项目中，我使用的是 swift 3.0。现在我正在使用以下类 (UILabel 子类) 根据 UILabel 框架高度调整字体大小。 当 UILabel 框架发生变化时，layoutSubviews 会重新计算比例字体大小。

class Label: UILabel {

    // FIXME: - properties
    var fontSize: CGFloat = 0
    var frameHeight: CGFloat = 0

    // FIXME: - proportional font size adjustment
    override func layoutSubviews() {
        super.layoutSubviews()
        font = font.withSize(frame.size.height * (fontSize / frameHeight))
    }
}

如何使用：

private let id: Label = {
        let label = Label()
        label.textAlignment = .left
        label.numberOfLines = 1
        label.font = UIFont.systemFont(ofSize: 17, weight: .semibold)
        label.textColor = UIColor(hex: 0x212121, alpha: 1)
        label.fontSize = 17
        label.frameHeight = 20
        label.clipsToBounds = true
        return label
    }()

现在我想在 UILabel 中将 String 的某些部分显示为 BOLD TEXT 并保留在 REGULAR TEXT 中。所以我在这个线程上找到了一些帮助：Making text bold using attributed string in swift

我正在为 NSMutableAttributedString 使用“Prajeet Shrestha's”扩展。

// "Prajeet Shrestha's" extension
extension NSMutableAttributedString {
    func bold(_ text:String) -> NSMutableAttributedString {
        let attrs:[String:AnyObject] = [NSFontAttributeName : UIFont(name: "AvenirNext-Medium", size: 12)!]
        let boldString = NSMutableAttributedString(string:"\(text)", attributes:attrs)
        self.append(boldString)
        return self
    }

    func normal(_ text:String)->NSMutableAttributedString {
        let normal =  NSAttributedString(string: text)
        self.append(normal)
        return self
    }
}

但是当 UILabel 帧发生更改时，我不知道如何更改此 NSMutableAttributedString 的字体大小？

任何帮助。

Answer 1

试试这个

来源Looping Through NSAttributedString Attributes to Increase Font SIze

 mutableStringObj?.enumerateAttribute(NSFontAttributeName, in: NSRange(location: 0, length: mutableStringObj?.length), options: [], usingBlock: {(_ value: Any, _ range: NSRange, _ stop: Bool) -> Void in
            if value {
                var oldFont: UIFont? = (value as? UIFont)
                var newFont: UIFont? = oldFont?.withSize(CGFloat(oldFont?.pointSize * 2))
                res?.removeAttribute(NSFontAttributeName, range: range)
                res?.addAttribute(NSFontAttributeName, value: newFont, range: range)
            }
        })

Answer 2

尝试像这样使用标签属性 adjustsFontSizeToFitWidth 和 minimumScaleFactor：

label.adjustsFontSizeToFitWidth = true
label.minimumScaleFactor = 0.2

那么你还需要增加这样的行数，而不是 10

label.numberOfLines = 10

Answer 3

终于想出答案了。

我创建了单独的自定义 UILabel 子类，如下所示：

class AttrLabel: UILabel {

    // FIXME: - properties
    var fontSize: CGFloat = 0
    var frameHeight: CGFloat = 0

    // FIXME: - proportional font size adjustment
    override func layoutSubviews() {
        super.layoutSubviews()

        guard let oldAttrText = attributedText else {
            return
        }

        let mutableAttributedText = NSMutableAttributedString(attributedString: oldAttrText)
        mutableAttributedText.beginEditing()

        mutableAttributedText.enumerateAttribute(NSFontAttributeName, in: NSRange(location: 0, length: mutableAttributedText.length), options: []) { (_ value: Any?, _ range: NSRange, _ stop: UnsafeMutablePointer<ObjCBool>) in
            if let attributeFont = value as? UIFont {
                let newFont = attributeFont.withSize(self.frame.size.height * (self.fontSize / self.frameHeight))
                mutableAttributedText.removeAttribute(NSFontAttributeName, range: range)
                mutableAttributedText.addAttribute(NSFontAttributeName, value: newFont, range: range)
            }
        }

        mutableAttributedText.endEditing()
        attributedText = mutableAttributedText
    }
}

如何使用：

private let id: AttrLabel = {
    let label = AttrLabel()
    label.textAlignment = .left
    label.numberOfLines = 1
    label.fontSize = 17
    label.frameHeight = 20
    label.clipsToBounds = true
    return label
}()

设置属性文本

let idStr = NSMutableAttributedString()
id.attributedText = idStr.attrStr(text: "BOLD TEXT: ", font: UIFont.systemFont(ofSize: 17, weight: .semibold), textColor: UIColor(hex: 0x212121, alpha: 1)).attrStr(text: "REGULAR WEIGHT TEXT.", font: UIFont.systemFont(ofSize: 17, weight: .regular), textColor: UIColor(hex: 0x212121, alpha: 1))

我修改的 NSMutableAttributedString 的“Prajeet Shrestha's”扩展

扩展 NSMutableAttributedString {

func attrStr(text: String, font: UIFont, textColor: UIColor) -> NSMutableAttributedString {
        let attributes: [String: Any] = [
                NSFontAttributeName: font,
                NSForegroundColorAttributeName: textColor
        ]
        let string = NSMutableAttributedString(string: text, attributes: attributes)
        self.append(string)
        return self
    }
}