问题描述
我很难理解为什么我必须在调用此视图时赋予名为vm的Popup视图依赖,因为它是可观察的
struct ContentView: View {
@State private var showPopup1 = false
var body: some View {
vstack {
Button(action: { withAnimation { self.showPopup1.toggle()}}){
Text("showPopup1") }
Text("title")
DetailView() /// this line shows error
}
}
}
struct DetailView:View {
@Observedobject var vm:viewmodel
var body : some View {
Text("value from VM")
}
}
class viewmodel: ObservableObject {
@Published var title:String = ""
}
解决方法
初始化视图时,必须设置vm属性。这是通常的方法。
struct ContentView: View {
@State private var showPopup1 = false
var body: some View {
VStack {
Button(action: { withAnimation { self.showPopup1.toggle()}}){
Text("showPopup1") }
Text("title")
DetailView(vm: ViewModel()) // Initiate your ViewModel() and pass it as DetailView() parameter
}
}
}
struct DetailView:View {
var vm: ViewModel
var body : some View {
Text("value from VM")
}
}
class ViewModel: ObservableObject {
@Published var title:String = ""
}
或者您可以使用@EnvironmentObject。您必须将.environmentObject(yourObject)传递到要使用Object的视图,但是同样,您必须在传递它之前对其进行初始化。
我不确定这是否是一个好方法,因为您声明了.environmentObject的视图的所有子视图都可以访问environmentObject,并且通常只需要一个ViewModel就可以使用一个视图。
struct ContentView: View {
@State private var showPopup1 = false
var body: some View {
VStack {
Button(action: { withAnimation { self.showPopup1.toggle()}}){
Text("showPopup1") }
Text("title")
DetailView().environmentObject(ViewModel()) // Pass your ViewModel() as an environmentObject
}
}
}
struct DetailView:View {
@EnvironmentObject var vm: ViewModel // you can now use your vm,and access it the same say in all childs view of DetailView
var body : some View {
Text("value from VM")
}
}
class ViewModel: ObservableObject {
@Published var title:String = ""
}