将空文本发送到服务 SwiftUI

Question

如果按钮值 .isCancel 为真，我想将 searchText 中的空文本发送到 AuthorService()。这样我的作者搜索结果就会被清理。

import SwiftUI
import Combine

struct AuthorSearchBar: View {
        @StateObject var service = AuthorService()
        @Binding var isCancel: Bool
        @State var emptyText = ""
        var body: some View {
            VStack(spacing: 0) {
               HStack {
                Image(systemName: "magnifyingglass")
                if isCancel == false{
                TextField("Search", text: $service.searchText)
                } else if isCancel {
                    TextField("Search", text: $service.searchText = "") 
            //Cannot assign to property: '$service' is immutable
            //Cannot assign value of type 'String' to type 'Binding<String>'
            //Cannot convert value of type '()' to expected argument type 'Binding<String>'
                }
                .padding()
                .onReceive(Just( self.isCancel ? emptyText : service.searchText), perform: { _ in
                    service.fetchData()
                })
            }
        }
}

我的服务 fetchData() 获取 searchText 参数如下。

所以如果 .isCancel 为真，我想将“”发送到 fetchData。

class AuthorService: ObservableObject {
@Published var searchText : String = ""
func fetchData() {
    let parameters = ["index": "authors", "query": "\(searchText)" ]

Answer 1

好吧，我仍然不确定我是否理解流程，但让我们试试...

有一些假设（在评论中提到），方法可能如下（原始代码不可测试，所以答案只是在这里准备 - 可能是错别字，适应是你的，但想法应该很清楚）：

struct AuthorSearchBar: View {

    @StateObject var service = AuthorService()
    @Binding var isCancel: Bool

    var body: some View {
        VStack(spacing: 0) {
           HStack {
             Image(systemName: "magnifyingglass")
             TextField("Search", text: $service.searchText)
                .padding()
           }
            .onReceive(Just(service.searchText)) { text in
                if !text.isEmpty {  // assuming search only for existed text
                   service.fetchData(for: text)
                }
            }
            .onReceive(Just(self.isCancel)) { canceled in
                if canceled {
                    // assuming needed to send on explicit cancel
                    service.fetchData(for: "")
                }
            }
        }
    }
}

// pass what should be sent via argument instead of use property
func fetchData(for text: String) {
    let parameters = ["index": "authors", "query": "\(text)" ]

    ...
}

备选方案： fetchData 没有变化，但在那种情况下，无法将输入的空字符串和取消时的大小写分开（尽管它不是清楚是否重要）。

   HStack {
     Image(systemName: "magnifyingglass")
     TextField("Search", text: $service.searchText)
        .padding()
   }
    .onReceive(Just(service.searchText)) { text in
        service.fetchData()
    }
    .onReceive(Just(self.isCancel)) { canceled in
        if canceled {
            service.searchText = ""  // << this activates above onReceive
        }
    }

将空文本发送到服务 SwiftUI

Send emptyText to Service SwiftUI

uitextfield

swiftui

combine