如何使用 Swift 制作项目符号列表？

Question

所以我想用 swift 和 xcode 做这样的事情：

我从数组中获取每个点。我的想法是制作一个 UILabel 并制作一个迭代数组的 for 循环，并在每次迭代中添加到标签 \u{2022} + 内容中。我知道 \u{2022} 是 unicode 中的点，问题是我需要一种方法将列表分成两列，如图所示，并使点颜色为黄色。如果我如上所述以编程方式添加点，则无法完成此操作，因为默认颜色将为黑色。由于点的数量因数组内容而异，例如，如果数组的大小为 3，那么只有 3 个点会在左侧显示 2，在右侧显示一个我需要一种方法来满足这个要求，我认为的另一种方法是有两个占屏幕一半的表格视图，并根据数组将此元素添加到每个表格视图中。这里的最佳实践应该是什么，或者有没有办法以依赖于数组的形式在情节提要中做到这一点。

Answer 1

在视图中为列使用 2 个标签。两个标签都被复用了

class Helper {

    static func bulletedList(strings:[String], textColor:UIColor, font:UIFont, bulletColor:UIColor, bulletSize:BulletSize) -> NSAttributedString {
        let textAttributesDictionary = [NSFontAttributeName : font, NSForegroundColorAttributeName:textColor]

        let bulletAttributesDictionary = [NSFontAttributeName : font.withSize(bulletSize.rawValue), NSForegroundColorAttributeName:bulletColor]
        let fullAttributedString = NSMutableAttributedString.init()

        for string: String in strings
        {
            let bulletPoint: String = "\u{2022}"
            let formattedString: String = "\(bulletPoint) \(string)\n"
            let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: formattedString)
            let paragraphStyle = createParagraphAttribute()

            attributedString.addAttributes([NSParagraphStyleAttributeName: paragraphStyle], range: NSMakeRange(0, attributedString.length))
            attributedString.addAttributes(textAttributesDictionary, range: NSMakeRange(0, attributedString.length))

            let string:NSString = NSString(string: formattedString)
            let rangeForBullet:NSRange = string.range(of: bulletPoint)

            attributedString.addAttributes(bulletAttributesDictionary, range: rangeForBullet)
            fullAttributedString.append(attributedString)
        }
        return fullAttributedString
    }

    static func createParagraphAttribute() -> NSParagraphStyle {

        var paragraphStyle: NSMutableParagraphStyle
        paragraphStyle = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
        paragraphStyle.tabStops = [NSTextTab(textAlignment: .left, location: 15, options: NSDictionary() as! [String : AnyObject])]
        paragraphStyle.defaultTabInterval = 15
        paragraphStyle.firstLineHeadIndent = 0
        paragraphStyle.lineSpacing = 3
        paragraphStyle.headIndent = 10
        return paragraphStyle
    }
}

只需使用Helper.bulletedList 将项目符号列表创建为标签的属性文本

Answer 2

在 Swift 中，tabStop 将适用于以下更改

let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.minimumLineHeight = 0 // 0 means unlimited
paragraphStyle.maximumLineHeight = 0
paragraphStyle.firstLineHeadIndent = 30
paragraphStyle.headIndent = 0
paragraphStyle.tabStops = [NSTextTab(textAlignment: .left, location: 15, options: Dictionary<NSTextTab.OptionKey, Any>())]
paragraphStyle.defaultTabInterval = 10  //changing defaultTabInterval changes the distance between black dot & text
paragraphStyle.lineSpacing = 5

Answer 3

对于 Swift 5，你可以使用这个类：

class NSAttributedStringHelper {
    static func createBulletedList(fromStringArray strings: [String], font: UIFont? = nil) -> NSAttributedString {

        let fullAttributedString = NSMutableAttributedString()
        let attributesDictionary: [NSAttributedString.Key: Any]
    
        if let font = font {
            attributesDictionary = [NSAttributedString.Key.font: font]
        } else {
            attributesDictionary = [NSAttributedString.Key: Any]()
        }
   
        for index in 0..<strings.count {
            let bulletPoint: String = "\u{2022}"
            var formattedString: String = "\(bulletPoint) \(strings[index])"
        
            if index < strings.count - 1 {
                formattedString = "\(formattedString)\n"
            }
        
            let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: formattedString, attributes: attributesDictionary)
            let paragraphStyle = NSAttributedStringHelper.createParagraphAttribute()
   attributedString.addAttributes([NSAttributedString.Key.paragraphStyle: paragraphStyle], range: NSMakeRange(0, attributedString.length))
        fullAttributedString.append(attributedString)
       }
    
        return fullAttributedString
    }

    private static func createParagraphAttribute() -> NSParagraphStyle {
        let paragraphStyle: NSMutableParagraphStyle = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
        paragraphStyle.tabStops = [NSTextTab(textAlignment: .left, location: 15, options: NSDictionary() as! [NSTextTab.OptionKey : Any])]
        paragraphStyle.defaultTabInterval = 15
        paragraphStyle.firstLineHeadIndent = 0
        paragraphStyle.headIndent = 11
        return paragraphStyle
    }
}

使用它：

let stringArray = ["first row", "second row", "third row"]
label.attributedText = NSAttributedStringHelper.createBulletedList(fromStringArray: stringArray, font: UIFont.systemFont(ofSize: 15))

Answer 4

我对上述解决方案不满意。所以这里有一个 Swifty 函数来获取项目符号列表：

func bulletPointList(strings: [String]) -> NSAttributedString {
    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.headIndent = 15
    paragraphStyle.minimumLineHeight = 22
    paragraphStyle.maximumLineHeight = 22
    paragraphStyle.tabStops = [NSTextTab(textAlignment: .left, location: 15)]

    let stringAttributes = [
        NSAttributedString.Key.font: regularSystem(size: 22),
        NSAttributedString.Key.foregroundColor: UIColor.black,
        NSAttributedString.Key.paragraphStyle: paragraphStyle
    ]

    let string = strings.map({ "•\t\($0)" }).joined(separator: "\n")

    return NSAttributedString(string: string,
                              attributes: stringAttributes)
}

这就是你使用它的方式：

label.numberOfLines = 0
label.attributedText = bulletPointList(strings: ["Foo", "Bar", "Lol"])