1

我又回来了哈哈。我的内容视图如下所示：

struct ContentView: View {
    @ObservedObject var VModel = ViewModel()
    @State private var resultsNeedToBeUpdated: Bool = false
    var body: some View {
        VStack {
            if self.resultsNeedToBeUpdated == true {
                SearchResults(VModel: VModel, resultsNeedToBeUpdated: $resultsNeedToBeUpdated)
            }
        }
    }
}

SearchBar 视图如下所示：

struct SearchResults: View {
    var VModel: ViewModel
    @Binding var resultsNeedToBeUpdated: Bool
    var body: some View {
        List {
            ForEach(VModel.searchResults, id: \.self) { result in 
                Text(result)
            }
        }
    }
}

最后，ViewModel 类看起来像：

class ViewModel: ObservableObject {
    @Published var searchResults: [String] = []
    func findResults(address: String) {
        let Geocoder = Geocoder(accessToken: 'my access token')
        searchResults = []
        Geocoder.geocode(ForwardGeocodeOptions(query: address)) { (placemarks, attribution, error) in
            guard let placemarks = placemarks
            else {
                return
            }
            for placemark in placemarks {
                self.searchResults.append(placemark.formattedName)
                print("Formatted name is: \(placemark.formattedName)") //this works
            }
        }
      //I'm doing my printing on this line and it's just printing an empty array ;(
}

变量 'resultsNeedToBeUpdated' 是一个布尔绑定，当用户在搜索栏视图中键入一些文本时会更新它，它本质上只是告诉您 SearchResults 视图如果为真则应显示，如果为假则不应显示. 我要做的是根据用户输入的内容更新 SearchResults 视图。

该错误肯定与 SearchResults 视图的显示有关（我认为它仅在数组更新之前显示初始视图）。我尝试使用绑定，因为我认为它会导致 ContentView 重新加载并且它会更新 SearchResultsView 但这不起作用。

4

1 回答 1

2

观察视图模型，在这种情况下，每次@Published var searchResults更改使用的属性时都会更新视图

struct SearchResults: View {
    @ObservedObject var VModel: ViewModel
//    @Binding var resultsNeedToBeUpdated: Bool // << not needed here

除上述已发布属性外，还应在主队列上更新，如

DispatchQueue.main.async {
    self.searchResults = placemarks.compactMap{ $0.formattedName }

//    for placemark in placemarks {
//        print("Formatted name is: \(placemark.formattedName)") //this works
//    }
}
于 2020-05-25T12:50:45.753 回答