如何解决从SwiftUI大纲中删除项目
我有一个SwiftUI大纲列表,希望从中删除选定的项目。这是视图(它是Xcode 12.2,Mac OS目标):
struct ContentView: View {
@State var root: GrimxnTree<String> = GrimxnTree<String>.testTree
@State var selection = Set<UUID>()
var body: some View {
vstack {
Text("Hello,Tree World!")
List(root.children,id: \.id,children: \.childrenorNil,selection: $selection) { e in
Text(e.payload)
}
.onDeleteCommand {
print("Delete \(self.selection)")
let s = selection
root.remove(ids: s)
selection = []
}
}
.frame(maxWidth: .infinity,maxHeight: .infinity)
}
}
该模型非常简单:
public struct GrimxnTree<Payload> {
var payload: Payload
var children: [GrimxnTree<Payload>] = []
var id = UUID()
var childrenorNil: [GrimxnTree<Payload>]? {
// This since `List` requires nil for no children,rather than []
children.count == 0 ? nil : children
}
mutating func remove(itemWithID id: UUID) {
guard id != self.id else {
fatalError("Can't delete root")
}
for i in 0 ..< self.children.count {
if self.children[i].id == id {
self.children.remove(at: i)
return
} else {
self.children[i].remove(itemWithID: id)
}
}
}
mutating func remove(ids: Set<UUID>) {
for id in ids {
self.remove(itemWithID: id)
}
}
// Some static methods to return sample trees...
static var testTree: GrimxnTree<String> { ... }
}
从菜单中选择“编辑/删除”总是会导致NSOutlineView错误,例如:
Outlinesketch [10597:853525] [常规] NSOutlineView错误消除 子索引
[索引数:4 (在1个范围内),索引:父级0x0(具有3个子级)中的索引((1-4)]。
我显然在做一些愚蠢的事情,但我完全看不到。谁能看到我要去哪里错了?
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