细节

Swift 5.2, Xcode 11.4 (11E146)

解决方案

protocol AttributedStringComponent {
    var text: String { get }
    func getAttributes() -> [NSAttributedString.Key: Any]?
}

// MARK: String extensions

extension String: AttributedStringComponent {
    var text: String { self }
    func getAttributes() -> [NSAttributedString.Key: Any]? { return nil }
}

extension String {
    func toAttributed(with attributes: [NSAttributedString.Key: Any]?) -> NSAttributedString {
        .init(string: self, attributes: attributes)
    }
}

// MARK: NSAttributedString extensions

extension NSAttributedString: AttributedStringComponent {
    var text: String { string }

    func getAttributes() -> [Key: Any]? {
        if string.isEmpty { return nil }
        var range = NSRange(location: 0, length: string.count)
        return attributes(at: 0, effectiveRange: &range)
    }
}

extension NSAttributedString {

    convenience init?(from attributedStringComponents: [AttributedStringComponent],
                      defaultAttributes: [NSAttributedString.Key: Any],
                      joinedSeparator: String = " ") {
        switch attributedStringComponents.count {
        case 0: return nil
        default:
            var joinedString = ""
            typealias SttributedStringComponentDescriptor = ([NSAttributedString.Key: Any], NSRange)
            let sttributedStringComponents = attributedStringComponents.enumerated().flatMap { (index, component) -> [SttributedStringComponentDescriptor] in
                var components = [SttributedStringComponentDescriptor]()
                if index != 0 {
                    components.append((defaultAttributes,
                                       NSRange(location: joinedString.count, length: joinedSeparator.count)))
                    joinedString += joinedSeparator
                }
                components.append((component.getAttributes() ?? defaultAttributes,
                                   NSRange(location: joinedString.count, length: component.text.count)))
                joinedString += component.text
                return components
            }

            let attributedString = NSMutableAttributedString(string: joinedString)
            sttributedStringComponents.forEach { attributedString.addAttributes($0, range: $1) }
            self.init(attributedString: attributedString)
        }
    }
}

使用

let defaultAttributes = [
    .font: UIFont.systemFont(ofSize: 16, weight: .regular),
    .foregroundColor: UIColor.blue
] as [NSAttributedString.Key : Any]

let marketingAttributes = [
    .font: UIFont.systemFont(ofSize: 20.0, weight: .bold),
    .foregroundColor: UIColor.black
] as [NSAttributedString.Key : Any]

let attributedStringComponents = [
    "pay for",
    NSAttributedString(string: "one",
                       attributes: marketingAttributes),
    "and get",
    "three!\n".toAttributed(with: marketingAttributes),
    "Only today!".toAttributed(with: [
        .font: UIFont.systemFont(ofSize: 16.0, weight: .bold),
        .foregroundColor: UIColor.red
    ])
] as [AttributedStringComponent]
let attributedText = NSAttributedString(from: attributedStringComponents, defaultAttributes: defaultAttributes)

完整的示例

不要忘记在这里粘贴解决方案代码

import UIKit

class ViewController: UIViewController {

    private weak var label: UILabel!
    override func viewDidLoad() {
        super.viewDidLoad()
        let label = UILabel(frame: .init(x: 40, y: 40, width: 300, height: 80))
        label.numberOfLines = 2
        view.addSubview(label)
        self.label = label

        let defaultAttributes = [
            .font: UIFont.systemFont(ofSize: 16, weight: .regular),
            .foregroundColor: UIColor.blue
        ] as [NSAttributedString.Key : Any]

        let marketingAttributes = [
            .font: UIFont.systemFont(ofSize: 20.0, weight: .bold),
            .foregroundColor: UIColor.black
        ] as [NSAttributedString.Key : Any]

        let attributedStringComponents = [
            "pay for",
            NSAttributedString(string: "one",
                               attributes: marketingAttributes),
            "and get",
            "three!\n".toAttributed(with: marketingAttributes),
            "Only today!".toAttributed(with: [
                .font: UIFont.systemFont(ofSize: 16.0, weight: .bold),
                .foregroundColor: UIColor.red
            ])
        ] as [AttributedStringComponent]
        label.attributedText = NSAttributedString(from: attributedStringComponents, defaultAttributes: defaultAttributes)
        label.textAlignment = .center
    }
}

结果

使用这个示例代码。这是满足您需求的非常短的代码。这对我很有用。

let attributes = [NSAttributedStringKey.font : UIFont(name: CustomFont.NAME_REGULAR.rawValue, size: CustomFontSize.SURVEY_FORM_LABEL_SIZE.rawValue)!]

let attributedString : NSAttributedString = NSAttributedString(string: messageString, attributes: attributes)

Swift使用与Obj-C相同的NSMutableAttributedString。你通过传入计算值作为字符串来实例化它:

var attributedString = NSMutableAttributedString(string:"\(calculatedCoffee)")

现在创建带属性的g字符串。注意:UIFont.systemFontOfSize(_)现在是一个可失败的初始化式，所以在你可以使用它之前，它必须被解除包装:

var attrs = [NSFontAttributeName : UIFont.systemFontOfSize(19.0)!]
var gString = NSMutableAttributedString(string:"g", attributes:attrs)

然后追加:

attributedString.appendAttributedString(gString)

然后你可以像这样设置UILabel来显示NSAttributedString:

myLabel.attributedText = attributedString

快4.倍

let attr = [NSForegroundColorAttributeName:self.configuration.settingsColor, NSFontAttributeName: self.configuration.settingsFont]

let title = NSAttributedString(string: self.configuration.settingsTitle,
                               attributes: attr)

在iOS上处理attributedstring的最好方法是使用接口构建器中内置的attributedtext编辑器，避免在源文件中不必要的硬编码NSAtrributedStringKeys。

你可以使用这个扩展在运行时动态替换占位符:

extension NSAttributedString {
    func replacing(placeholder:String, with valueString:String) -> NSAttributedString {

        if let range = self.string.range(of:placeholder) {
            let nsRange = NSRange(range,in:valueString)
            let mutableText = NSMutableAttributedString(attributedString: self)
            mutableText.replaceCharacters(in: nsRange, with: valueString)
            return mutableText as NSAttributedString
        }
        return self
    }
}

添加带有带属性文本的故事板标签，如下所示。

然后你只需在你需要的时候更新这个值，就像这样:

label.attributedText = initalAttributedString.replacing(placeholder: "<price>", with: newValue)

确保将原始值保存到initalAttributedString中。

你可以通过阅读这篇文章来更好地理解这种方法: https://medium.com/mobile-appetite/text-attributes-on-ios-the-effortless-approach-ff086588173e

斯威夫特3、4、5所示

使用下面的代码为文本颜色，字体，背景颜色和下划线/下划线颜色

    let text = "swift is language"
    let attributes = [NSAttributedString.Key.foregroundColor: UIColor.red, NSAttributedString.Key.backgroundColor: UIColor.blue,NSAttributedString.Key.font: UIFont.systemFont(ofSize: 25.0),NSAttributedString.Key.underlineColor: UIColor.white,NSAttributedString.Key.underlineStyle: NSUnderlineStyle.single.rawValue] as [NSAttributedString.Key : Any]
        
    let textAttribute = NSAttributedString(string: text, attributes: attributes)
    swiftLabel1.attributedText = textAttribute