如何使用 SwiftUI 的 ToolbarItemGroup? [英] How does one use SwiftUI's ToolbarItemGroup?

问题描述

我显然不明白 SwiftUI 定义语法的含义，因为我不知道如何使用 ToolbarItemGroup.

I clear don't understand the meaning of the definition syntax for SwiftUI because I can't figure out how one would use ToolbarItemGroup.

我可以用这样的工具栏项目定义一个工具栏:

I can define a toolbar with toolbar items like this:

.toolbar {
            
            ToolbarItem {
                Button("200%", action: zoom200).foregroundColor(controller.scale == 2.0 ? selectedButtonColor : defaultButtonColor)
            }
            ToolbarItem {
                Button("100%", action: zoom100).foregroundColor(controller.scale == 1.0 ? selectedButtonColor : defaultButtonColor)
            }
}

但是一直无法让 ToolbarItemGroup 工作.从逻辑上讲，我会期待这样的事情:

But have been unable to get ToolbarItemGroup to work. Logically I would have expected something like this:

.toolbar {
   ToolbarItemGroup {
            
         ToolbarItem {
                Button("200%", action: zoom200).foregroundColor(controller.scale == 2.0 ? selectedButtonColor : defaultButtonColor)
            }
         ToolbarItem {
                Button("100%", action: zoom100).foregroundColor(controller.scale == 1.0 ? selectedButtonColor : defaultButtonColor)
            }
   }
   ToolbarItemGroup {
         ToolbarItem {
                Button("Open", action: open)
            }
         ToolbarItem {
                Button("Close", action: close)
            }
   }
}

推荐答案

ToolbarItemGroup 是输出实体，而不是输入 - 从以下 toolbar 构建器中可以清楚地看出:

The ToolbarItemGroup is output entity, not input - as it is clear from the following toolbar builders:

/// Populates the toolbar or navigation bar with the specified items.
///
/// - Parameter items: The items representing the content of the toolbar.
public func toolbar<Items>(@ToolbarContentBuilder<Void> items: () -> ToolbarItemGroup<Void, Items>) -> some View


/// Populates the toolbar or navigation bar with the specified items,
/// allowing for user customization.
///
/// - Parameters:
///   - id: A unique identifier for this toolbar.
///   - items: The items representing the content of the toolbar.
public func toolbar<Items>(id: String, @ToolbarContentBuilder<String> items: () -> ToolbarItemGroup<String, Items>) -> some View

因此，.toolbar 会根据工具栏项目的位置(按预定义的顺序)自动生成组.

Thus groups are generated automatically by .toolbar based on toolbar items placement (in predefined order).

这是示例(使用 Xcode 12b/iOS 14 测试)

Here is example (tested with Xcode 12b / iOS 14)

.toolbar {
    ToolbarItem(placement: .primaryAction) {
        Button(action: {}) { Image(systemName: "book") }
    }
    ToolbarItem(placement: .primaryAction) {
        Button(action: {}) { Image(systemName: "gear") }
    }
    ToolbarItem(placement: .principal) {
        Button(action: {}) { Image(systemName: "car") }
    }
    ToolbarItem(placement: .principal) {
        Button(action: {}) { Image(systemName: "gear") }
    }
    ToolbarItem(placement: .bottomBar) {
        Button(action: {}) { Image(systemName: "1.square") }
    }
    ToolbarItem(placement: .bottomBar) {
        Button(action: {}) { Image(systemName: "2.square") }
    }
}

这篇关于如何使用 SwiftUI 的 ToolbarItemGroup?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！