SwiftUI - 文本字段返回键事件

Question

首先，我很抱歉我的英语并不完美。

我想根据通过文本字段中的返回键接收到的值的条件显示不同的图像。我搜索并尝试了多种方法，但找不到正确的方法。我在 SwiftUI 中找不到合适的返回键事件，所以我尝试了 onReceive。

快速文件。

struct QuestionItemView: View {

    @State private var question: Question?
    @State private var answer = ""

    var body: some View {
        VStack(spacing: 30) {
            GroupBox {
                if let question = question {
                    Text(question.question)
                        .font(.largeTitle)
                        .fontWeight(.heavy)
                        .scaledToFit()
                        .frame(width: 300, height: 100)
                        .cornerRadius(12)
                }
            }
        
            GroupBox {
                TextField("Enter your answer", text: $answer)
                    .frame(width: 300)
                    .font(.title2)
                    .scaledToFit()
                    .cornerRadius(12)
                    .multilineTextAlignment(.center)
           }
         
            onReceive(answer.publisher) { _ in
                if answer == question?.answer {
//                        Image(systemName: "circle")
                    print("o")
                } else {
//                        Image(systemName: "multiply")
                    print("x")
                }
            }
        } //: VStack
        .frame(width: 240)
        .background(RoundedRectangle(cornerRadius: 7.0).fill(Color.white))
        .onAppear {
            let questions: [Question] = Bundle.main.decode("questions.json")
            question = questions.randomElement()
        }
    }
}

json.文件

[
    {
        "id" : 1,
        "question" : "2 X 6",
        "answer" : "12"
    },
    {
        "id" : 2,
        "question" : "7 + 8",
        "answer" : "15"
    },
    {
        "id" : 3,
        "question" : "9 - 1",
        "answer" : "8"
    },
    {
        "id" : 4,
        "question" : "4 / 2",
        "answer" : "2"
    },
    {
        "id" : 5,
        "question" : "10 X 2",
        "answer" : "20"
    }
]

Answer 1

你可以尝试这样的事情：

struct QuestionItemView: View {
    
    @State private var question: Question?
    @State private var answer = ""
    @State private var imgType = ""
    
    var body: some View {
        VStack(spacing: 30) {
            GroupBox {
                if let question = question {
                    Text(question.question)
                        .font(.largeTitle)
                        .fontWeight(.heavy)
                        .scaledToFit()
                        .frame(width: 300, height: 100)
                        .cornerRadius(12)
                }
            }
            
            GroupBox {
                TextField("Enter your answer", text: $answer)
                    .frame(width: 300)
                    .font(.title2)
                    .scaledToFit()
                    .cornerRadius(12)
                    .multilineTextAlignment(.center)
                    .onSubmit {  // <--- only on pressing the return key
                //  .onChange(of: answer) { _ in  // <-- as you type
                //  .onReceive(answer.publisher) { _ in  // <-- as you type
                    if answer == question?.answer {
                        imgType = "circle"
                        print("o")
                    } else {
                        imgType = "multiply"
                        print("x")
                    }
                }
            }
            
            if imgType == "circle" {
                Image(systemName: "circle")
            } else {
                Image(systemName: "multiply")
            }

        }
        .frame(width: 240)
        .background(RoundedRectangle(cornerRadius: 7.0).fill(Color.white))
        .onAppear {
            let questions: [Question] = Bundle.main.decode("questions.json")
            question = questions.randomElement()
        }
    }
}

如果您使用的是较旧的系统，您可能需要执行以下操作：

        TextField("Enter your answer", text: $answer, onCommit: {
            if answer == question?.answer {
                imgType = "circle"
                print("o")
            } else {
                imgType = "multiply"
                print("x")
            }
        })