如何使用BindableObjects(EnviromentObject)? [英] How to use BindableObjects (EnviromentObject)?

问题描述

我正在使用新的SwiftUI.我有一个 UserUpdate 类，它是一个 Bindable Object ，我想修改这些变量并自动更新UI.

Im using the new SwiftUI. I have a UserUpdate class which is a Bindable Object and I want to modify these variables and automatically Update the UI.

我成功更新了这些值，但是当我更改 UserUpdate 类中的变量时，我的UI结构中的视图没有更新.

I update these Values successfully but the views in my UI struct isn't updating when I change the variable in the UserUpdate class.

当我在UI结构本身中修改 @EnviromentObject 变量时，仅会更改.

It only changes when I modify the @EnviromentObject variable in the UI struct itself.

那是我的可绑定对象类:

That's my Bindable Object Class:

final class UserUpdate: BindableObject {
    let didChange = PassthroughSubject<Any, Never>()

    var allUsers: [User] = [] {
        didSet {
            print(allUsers)
            didChange.send(allUsers)
        }
    }

    var firstName: String = "" {
        didSet {
            didChange.send(firstName)
        }
    }

    var lastName: String = "" {
        didSet {
            didChange.send(lastName)
        }
    }
}

那是我的User类:

struct User: Identifiable {
    let id: Int
    let firstName, lastName: String
}

这是我配置用户界面的方式:

Here's how I configure my UI:

struct ContentView : View {
    @EnvironmentObject var bindableUser: UserUpdate

    var body: some View {
        NavigationView {
            VStack(alignment: .leading) {
                Text("All Users:").bold().padding(.leading, 10)
                List {
                    ForEach(bindableUser.allUsers) { user in
                        Text("\(user.firstName) \(user.lastName)")
                    }
                }
            }
        }
    }
}

在这里我修改 UserUpdate 中的变量:

Here I modify the variables in UserUpdate:

class TestBind {
    static let instance = TestBind()

    let userUpdate = UserUpdate()

    func bind() {
        let user = User(id: userUpdate.allUsers.count, firstName: "Heyy", lastName: "worked")
        userUpdate.allUsers.append(user)
    }
}

推荐答案

我发现我必须从UI调用该方法才能使其正常工作，因此它可以在同一流上使用.

I found out that I had to call the method from my UI to get it working so its on the same stream.

例如:

struct ContentView : View {
@EnvironmentObject var networkManager: NetworkManager

var body: some View {
    VStack {
        Button(action: {
            self.networkManager.getAllCourses()
        }, label: {
            Text("Get All Courses")
        })

        List(networkManager.courses.identified(by: \.name)) {
            Text($0.name)
        }
    }
}
}

这篇关于如何使用BindableObjects(EnviromentObject)?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！