[英]EnvironmentObject in protocol of SwiftUI View
我想制作这样的协议:
protocol SubscriptionManagerView: View {
var subscriptionManager: EnvironmentObject<SubscriptionManager> { get set }
}
像这样在视图中使用,例如:
struct Shop: View, SubscriptionManager {
@EnvironmentObject var subscriptionManager: SubscriptionManager
第一个问题是属性包装器@EnvironmentObject 不能让我响应协议 SubscriptionManagerView。
最后,我想用于这样的自定义修饰符:
extension View where Self : SubscriptionManagerView {
func subscriptionManagerAlert() -> some View {
self.alert(isPresented: self.$subscriptionManager.stateShowAlert) {
Alert(title: Text(self.subscriptionManager.transactionStateTitle)
...
}))
}
}
}
任何想法以这种方式工作?
这是一个可能的方法的演示 - 想法是使用带有显式注入订阅管理器的视图修饰符,因此接口合同保证修饰符的客户端视图将为我们提供所需的对象。
使用 Xcode 12 / iOS 14 测试。
class SubscriptionManager: ObservableObject {
@Published var stateShowAlert: Bool = false
@Published var transactionStateTitle = "Test"
}
struct SubscriptionManagerModifier: ViewModifier {
@ObservedObject var subscriptionManager: SubscriptionManager
func body(content: Content) -> some View {
content
.alert(isPresented: self.$subscriptionManager.stateShowAlert) {
Alert(title: Text(self.subscriptionManager.transactionStateTitle))
}
}
}
extension View {
func subscriptionManagerAlert(with subscriptionManager: SubscriptionManager) -> some View {
self.modifier(SubscriptionManagerModifier(subscriptionManager: subscriptionManager))
}
}
struct Shop: View {
@EnvironmentObject var subscriptionManager: SubscriptionManager
var body: some View {
Button("Test") {
subscriptionManager.stateShowAlert.toggle()
}
.subscriptionManagerAlert(with: subscriptionManager)
}
}
struct Shop_Previews: PreviewProvider {
static var previews: some View {
Shop().environmentObject(SubscriptionManager())
}
}
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