SwiftUI 中的 List 和 ForEach 有什么区别? [英] What is the difference between List and ForEach in SwiftUI?

问题描述

我知道 SwiftUI 目前不支持常规的 for 循环，而是提供了一种叫做 ForEach 的东西，但这和 List 有什么区别?

I know SwiftUI does not support currently regular for loops but instead provide something called ForEach but what is the difference between that and a List?

推荐答案

• ForEach 是一个视图，它允许您将一组数据传递给其初始值设定项，然后根据您提供的闭包创建多个子视图".它没有关于如何安排视图的任何语义.

  • ForEach is a view that lets you pass a collection of data to its initializer and then creates multiple "subviews" from the closure you provide. It doesn't have any semantics on how the views will be arranged.

    ForEach(1...5) { row in
        Text("Row \(row)")
    }
    

    将创建等效的关闭

    Text("Row 1")
    Text("Row 2")
    Text("Row 3")
    Text("Row 4")
    Text("Row 5")
    

    包装在单个容器视图中.

    wrapped in a single container view.

    List 是一种可以将多个视图组合在一起的视图，但不一定是同一类型的视图.您可以简单地添加多个视图而无需任何循环.

    List is a view that can compose multiple views together, but not necessarily views of the same type. You can simply add multiple views without any loop.

    List {
        Image("avatar")
        Text("Title")
        Button(action: {
            print("Button tapped!")
        }) {
            Text("Energize!")
        }
    }
    

    作为一个方便，List 初始值设定项允许您像使用 ForEach 视图一样使用它，以防您想要包含一个列表仅限单一细胞类型.
    

    As a convenience, the List initializer allows you to use it just like the ForEach view in case you want to have a list consisting of a single cell type only.
    

    List(1...5) { row in
        Text("Row \(row)")
    }
    

    列表具有特殊的外观，具体取决于平台.例如，在 iOS 上，列表将显示为表格视图，并在其垂直堆叠的视图之间插入分隔线.

    A list has a special appearance, depending on the platform. For example, on iOS a list will appear as a table view and insert separator lines between its vertically stacked views.

    您可以在 List 视图中使用 ForEach 视图来拥有动态和静态内容 - SwiftUI 的一个非常强大的功能.
    
    

    You can use ForEach views inside List views to have both dynamic and static content – a very powerful feature of SwiftUI.
    
    

    List {
        Text("Food")
        ForEach(meals) { meal in
            Text(meal.name)
        }
        Text("Drinks")
        ForEach(drinks) { drink in
            Text(drink.name)
        }
    }
    

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