在 Swift 中仅更改 AttributedText 的字体

Question

我在 IB 中创建了许多 UILabel，它们都有属性文本。每个标签的文本包含多行不同的字体大小和颜色。

在运行时间，我希望能够只更改这些标签的字体名称而不更改现有的字体大小或颜色。

我已经研究过但找不到实现此目的的直接方法。有什么想法吗？

Answer 1

您首先需要了解 Apple 用来描述字体的行话：

Helvetica是一个家庭
Helvetica Bold、Helvetica Italic、Helvetica Bold Italic、Helvetica Display等都是面
Helvetica Bold, 12pt 是一个字体

您想要的是替换属性字符串的字体系列。

Swift 4

// Enumerate through all the font ranges
newAttributedString.enumerateAttribute(.font, in: NSMakeRange(0, newAttributedString.length), options: []) { value, range, stop in
    guard let currentFont = value as? UIFont else {
        return
    }

    // An NSFontDescriptor describes the attributes of a font: family name,
    // face name, point size, etc. Here we describe the replacement font as
    // coming from the "Hoefler Text" family
    let fontDescriptor = currentFont.fontDescriptor.addingAttributes([.family: "Hoefler Text"])

    // Ask the OS for an actual font that most closely matches the description above
    if let newFontDescriptor = fontDescriptor.matchingFontDescriptors(withMandatoryKeys: [.family]).first {
        let newFont = UIFont(descriptor: newFontDescriptor, size: currentFont.pointSize)
        newAttributedString.addAttributes([.font: newFont], range: range)
    }
}

label.attributedText = newAttributedString

Swift 3

let newAttributedString = NSMutableAttributedString(attributedString: label.attributedText)

// Enumerate through all the font ranges
newAttributedString.enumerateAttribute(NSFontAttributeName, in: NSMakeRange(0, newAttributedString.length), options: []) { value, range, stop in
    guard let currentFont = value as? UIFont else {
        return
    }

    // An NSFontDescriptor describes the attributes of a font: family name,
    // face name, point size, etc. Here we describe the replacement font as
    // coming from the "Hoefler Text" family
    let fontDescriptor = currentFont.fontDescriptor.addingAttributes([UIFontDescriptorFamilyAttribute: "Hoefler Text"])

    // Ask the OS for an actual font that most closely matches the description above
    if let newFontDescriptor = fontDescriptor.matchingFontDescriptors(withMandatoryKeys: [UIFontDescriptorFamilyAttribute]).first {
        let newFont = UIFont(descriptor: newFontDescriptor, size: currentFont.pointSize)
        newAttributedString.addAttributes([NSFontAttributeName: newFont], range: range)
    }
}

label.attributedText = newAttributedString

原文（旧金山）：

替换（Hoefler 文本）：

Answer 2

上面的方法很好用，但是对于 Swift4 和 Xcode 9.1，我收到了很多方法名称已更改的警告。以下是应用所有这些警告的结果。否则我什么都没改。

let newAttributedString = NSMutableAttributedString(attributedString: label.attributedText!)

// Enumerate through all the font ranges
newAttributedString.enumerateAttribute(NSAttributedStringKey.font, in: NSMakeRange(0, newAttributedString.length), options: []) 
{   
    value, range, stop in
    guard let currentFont = value as? UIFont else {
        return
    }

    // An NSFontDescriptor describes the attributes of a font: family name, face name, point size, etc.
    // Here we describe the replacement font as coming from the "Hoefler Text" family
    let fontDescriptor = currentFont.fontDescriptor.addingAttributes([UIFontDescriptor.AttributeName.family: "Hoefler Text"])

    // Ask the OS for an actual font that most closely matches the description above
    if let newFontDescriptor = fontDescriptor.matchingFontDescriptors(withMandatoryKeys: [UIFontDescriptor.AttributeName.family]).first {
        let newFont = UIFont(descriptor: newFontDescriptor, size: currentFont.pointSize)
        newAttributedString.addAttributes([NSAttributedStringKey.font: newFont], range: range)
    }
}

label.attributedText = newAttributedString

在 Swift 中仅更改 AttributedText 的字体

Change just Font of AttributedText in Swift

ios

swift

nsattributedstring

uifont

Swift 4

Swift 3