SwiftUI中如何在Text视图显示NSMutableAttributedString并修改所有星号样式

1. 匹配所有星号并修改样式 #

原代码里的range(of:)只会匹配第一个星号，要批量修改所有星号的样式，需要循环遍历查找所有匹配位置，直到找不到为止。修改后的代码如下：

func customDesc(_ text: String) -> NSMutableAttributedString {
    let attributedString = NSMutableAttributedString(string: text, attributes: [
        .font: UIFont.systemFont(ofSize: 15, weight: .semibold)
    ])
    
    let asterisk = "*"
    var searchRange = NSRange(location: 0, length: attributedString.length)
    var foundRange = (text as NSString).range(of: asterisk, options: [], range: searchRange)
    
    while foundRange.location != NSNotFound {
        attributedString.setAttributes([
            .font: UIFont.systemFont(ofSize: 20, weight: .heavy)
        ], range: foundRange)
        
        // 更新搜索范围，从当前匹配位置的下一个字符开始继续查找
        searchRange = NSRange(location: foundRange.location + foundRange.length, length: attributedString.length - (foundRange.location + foundRange.length))
        foundRange = (text as NSString).range(of: asterisk, options: [], range: searchRange)
    }
    
    return attributedString
}

2. 在SwiftUI中显示富文本 #

SwiftUI的Text视图无法直接接收NSMutableAttributedString，可以通过以下两种方式解决：

方式一：封装UIKit的UILabel（兼容iOS 13+） #

创建一个UIViewRepresentable封装视图，用来承载UIKit的UILabel显示富文本：

struct AttributedText: UIViewRepresentable {
    let attributedString: NSAttributedString
    
    func makeUIView(context: Context) -> UILabel {
        let label = UILabel()
        label.numberOfLines = 0 // 支持多行文本
        label.attributedText = attributedString
        return label
    }
    
    func updateUIView(_ uiView: UILabel, context: Context) {
        uiView.attributedText = attributedString
    }
}

使用示例：

struct ContentView: View {
    let originalText = "The * quick * brown * fox * jumps * over * the * lazy * dog"
    
    var body: some View {
        AttributedText(attributedString: customDesc(originalText))
            .padding()
    }
    
    // 这里放入前面的customDesc方法
    func customDesc(_ text: String) -> NSMutableAttributedString {
        // ... 实现代码
    }
}

方式二：使用SwiftUI原生AttributedString（iOS 15+） #

如果项目支持iOS 15及以上版本，直接用SwiftUI原生的AttributedString更简洁：

func customSwiftUIText(_ text: String) -> AttributedString {
    var attributedString = AttributedString(text)
    // 设置全局基础字体
    attributedString.font = Font.system(size: 15, weight: .semibold)
    
    // 遍历所有星号并修改样式
    for range in attributedString.ranges(of: "*") {
        attributedString[range].font = Font.system(size: 20, weight: .heavy)
    }
    
    return attributedString
}

使用示例：

struct ContentView: View {
    let originalText = "The * quick * brown * fox * jumps * over * the * lazy * dog"
    
    var body: some View {
        Text(customSwiftUIText(originalText))
            .padding()
    }
    
    func customSwiftUIText(_ text: String) -> AttributedString {
        // ... 实现代码
    }
}

内容的提问来源于stack exchange，提问作者batman