SwiftUI 的新手......我有以下簡化代碼。預期的功能是能夠在View1()和之間導航View2()，使用單例類來跟蹤此導航。
我懷疑也許我需要添加@Published到我的show_view_2變數中，但我想將它保存在 App Storage 中。另外，我知道這不是在視圖之間切換的最佳方式，但我只使用這種方法，因為它是一個最少復制的示例。
為什么下面的代碼不起作用，我怎樣才能使它起作用？
class Player {
static var player = Player()
@AppStorage("show_view_2") var show_view_2: Bool = false
}
struct ContentView: View {
var body: some View {
if(Player.player.show_view_2) {
View2()
} else {
Text("Go to View2")
.onTapGesture {
Player.player.show_view_2 = true
}
}
}
}
struct View2: View {
var body: some View {
Text("Back to View1")
.onTapGesture {
Player.player.show_view_2 = false
}
}
}
uj5u.com熱心網友回復：
要讓 SwiftUI 知道要更新，Player應該是ObservableObject. 此外，它需要使用屬性包裝器（@StateObject或@ObservedObject）訪問View：
class Player : ObservableObject {
static var player = Player()
@AppStorage("show_view_2") var show_view_2: Bool = false
}
struct ContentView: View {
@StateObject private var player = Player.player
var body: some View {
if player.show_view_2 {
View2()
} else {
Text("Go to View2")
.onTapGesture {
player.show_view_2 = true
}
}
}
}
struct View2: View {
@StateObject private var player = Player.player
var body: some View {
Text("Back to View1")
.onTapGesture {
player.show_view_2 = false
}
}
}
一般來說，我建議不要使用單例，而是在視圖之間顯式傳遞物件的實體——隨著時間的推移，這將更加可測驗和靈活：
class Player : ObservableObject {
@AppStorage("show_view_2") var show_view_2: Bool = false
}
struct ContentView: View {
@StateObject private var player = Player()
var body: some View {
if player.show_view_2 {
View2(player: player)
} else {
Text("Go to View2")
.onTapGesture {
player.show_view_2 = true
}
}
}
}
struct View2: View {
@ObservedObject var player : Player
var body: some View {
Text("Back to View1")
.onTapGesture {
player.show_view_2 = false
}
}
}
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