如何在Xcode中使用#Preview宏？Xcode15预览代码重构求助

一、#Preview宏基础用法 #

Xcode15引入的#Preview宏彻底简化了SwiftUI预览写法，不用再写繁琐的PreviewProvider结构体：

• 直接用#Preview声明预览块，括号里可给预览加名称（可选）
• 宏的闭包内直接返回要预览的视图，也可提前准备好数据源再传入
• 多个预览需求直接写多个#Preview块即可，互不干扰
• 还能快速设置预览设备、深色模式等特性，比如#Preview(device: .iPhone15, traits: .darkMode) { ... }

二、你的代码重构适配 #

针对你提供的HistoryView_Previews代码，用#Preview宏重构后的写法有两种：

写法一：提前抽离测试数据（更易复用） #

// 定义预览专用的测试数据
private let previewHistory = History(attendees: [
    DailyScrum.Attendee(name: "Jon"),
    DailyScrum.Attendee(name: "Darla"),
    DailyScrum.Attendee(name: "Luis")
],
transcript: "Darla, would you like to start today? Sure, yesterday I reviewed Luis' PR and met with the design team to finalize the UI...")

// 创建预览
#Preview("历史记录视图") {
    HistoryView(history: previewHistory)
}

写法二：数据内嵌在预览块中（更紧凑） #

#Preview("历史记录视图") {
    let history = History(attendees: [
        DailyScrum.Attendee(name: "Jon"),
        DailyScrum.Attendee(name: "Darla"),
        DailyScrum.Attendee(name: "Luis")
    ],
    transcript: "Darla, would you like to start today? Sure, yesterday I reviewed Luis' PR and met with the design team to finalize the UI...")
    return HistoryView(history: history)
}

两种写法都能在Xcode15中正常显示HistoryView的预览，选哪种看你对代码复用的需求。

内容的提问来源于stack exchange，提问作者fuRjNg JGYKK