我的视图在SwiftUI中一遍又一遍地呈现

提问者：小点点

我的视图在SwiftUI中一遍又一遍地呈现

以下是我的看法:

struct EditProfile: View {
    @State var bio = UserDefaults.standard.string(forKey: "bio") ?? "Edit your bio"
    @ObservedObject var storage = FirebaseStorage()
    @State var text = ""
    let photos = ["img1", "img2", "img3"]
    var body: some View {
        VStack {
            Text("Photos")
            .font(Font.system(size: 21))
            .fontWeight(.bold)
            HStack {
                ForEach(photos, id: \.self){ img in
                    EditableCircleImage(kfImage: self.storage.makeCircleImage(str: img))
                }
            }
            .background(
                RoundedRectangle(cornerRadius: 10)
                    .fill(Color.white)
                    .shadow(color: .gray, radius: 1, x: 0, y: 1)
            )

            Text("Bio")
                .font(Font.system(size: 21))
                .fontWeight(.bold)
            MultiTextField(txt: $text)
                .padding(10)
                .cornerRadius(20.0)
                .background(
                    RoundedRectangle(cornerRadius: 10)
                        .fill(Color.white)
                        .shadow(color: .gray, radius: 1, x: 0, y: 1)
                )
                .border(Color.gray.opacity(0.5), width: 1)

        }.padding(20).background(Color.gray.opacity(0.1))
    }
}

下面是EditableCircleImage():

struct EditableCircleImage: View {
    let kfImage: KFImage
    var body: some View {
        ZStack {
            kfImage
                .resizable()
            .scaledToFit()
            .frame(height: 200)
                .clipShape(Circle())
                .overlay(Circle().stroke(Color.orange, lineWidth: 2))
            Button(action: {}){
                Image(systemName: "pencil.circle.fill")
                    .resizable()
                    .scaledToFit()
                    .frame(height: 40)
                .foregroundColor(.gray)

            }.offset(x: 40, y: 50)
        }
    }
}

下面是返回图像的模型:FireBaseStorage.swift:

class FirebaseStorage: ObservableObject {
    let storage = Storage.storage()
    let uid = UserAuth().uid ?? "<uid>"
    @Published var img1 = UserDefaults.standard.string(forKey: "img1") ?? "<img1>"

    func makeCircleImage(str: String) -> KFImage {
        if let url = UserDefaults.standard.string(forKey: str) {
            print("not nil: \(str)")
            return KFImage(URL(string: "http://app-23c8s.appspot.com.storage.googleapis.com/users/\(uid)/\(url)"))
        }
        else {
            print("is nil: \(str)")
            return KFImage(source: nil)
        }

    }
}

上面模型中的print语句一遍又一遍地打印，即使在初始呈现后没有任何值发生变化。知道为什么吗？

不断打印:

not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3
not nil: img1
is nil: img2
is nil: img3

更新:

我改了:

ForEach(photos, id: \.self){ img in
    EditableCircleImage(kfImage: self.storage.makeCircleImage(str: img))
}

至

EditableCircleImage(kfImage: self.storage.makeCircleImage(str: "img1"))

现在它打印:

not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1
not nil: img1

共2个答案

匿名用户

移除FirebaseStorage类与ObservableObject的一致性，并从@ObservedObject var storage=FirebaseStorage()中移除属性包装器@ObservedObject。也删除@Published属性包装。运行它，如果问题仍然存在，请告诉我。顺便说一下，我不清楚为什么要使类符合ObservableObject，以及为什么要在这个特定的用例中使用属性包装器。如果我遗漏了什么，一定要让我知道。假设这篇文章包含了您正在谈论的问题的整个代码。希望这能帮到你。

匿名用户

看来

func makeCircleImage(str: String) -> KFImage { ... }

是一个异步函数，特别是KFImage（。。）。您可以在以下情况下使用此选项:

ForEach(photos, id: \.self){ img in
     EditableCircleImage(kfImage: self.storage.makeCircleImage(str: img))
}

这大概就是问题的源头。你真的应该等到你拥有了所有的图像之后再使用它们，尤其是在一个视图中。