SwiftUI视图协议中的EnvironmentObject

我想制定如下协议：

protocol SubscriptionManagerView: View {
    var subscriptionManager: EnvironmentObject<SubscriptionManager> { get set }
}

extension View where Self : SubscriptionManagerView {
    func subscriptionManagerAlert() -> some View {
        self.alert(isPresented: self.$subscriptionManager.stateShowAlert) {
            Alert(title: Text(self.subscriptionManager.transactionStateTitle)
                ...
                  }))
        }
    }
}

第一个问题是属性包装器@EnvironmentObject无法使我响应协议SubscriptionManagerView

最后，我想使用如下自定义修改器：

protocol SubscriptionManagerView: View {
    var subscriptionManager: EnvironmentObject<SubscriptionManager> { get set }
}

extension View where Self : SubscriptionManagerView {
    func subscriptionManagerAlert() -> some View {
        self.alert(isPresented: self.$subscriptionManager.stateShowAlert) {
            Alert(title: Text(self.subscriptionManager.transactionStateTitle)
                ...
                  }))
        }
    }
}

---

有没有这样的想法？

这里是一个可能方法的演示-想法是将视图修改器与显式注入的subscription manager一起使用，因此接口契约保证修改器的客户端视图将为我们提供所需的对象

使用Xcode 12/iOS 14进行测试

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())
    }
}

---

@EnvironmentObject-var-subscriptionManager:subscriptionManager

不相等

var-subscriptionManager:EnvironmentObject

非常感谢！我好奇地想知道是否有任何使用协议的方法……这有点愚蠢；不是在你执行它，而是在需要它。这只是一个无法将多个对象推入环境的问题，还是环境不可靠？