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swift - SwiftUI @AppStorage 不在函数中刷新

问题描述

我试图在每个 .onAppear 中重新加载数据，但是如果我在 SettingsView 中更改 @AppStorage nearMeter 的值，它不会更新 reloadNearStops 函数中的值并使用之前的 @AppStorage 值。

    struct SettingsView: View {
        @AppStorage(“nearMeter”) var nearMeter: Int = 1
        @State var meters = ["100 m","200 m","400 m","500 m","750 m","1 km"]
    
    var body: some View {


    ………
    
                            Picker(selection: $nearMeter, label: HStack {
                                    Text(NSLocalizedString(“near_stops_distance”, comment: ""))
                            }) {
                                ForEach(0 ..< meters.count, id: \.self) {
                                        Text(meters[$0])
                                }
                            }}}



    struct FavouritesView: View {
 @AppStorage(“nearMeter”) var nearMeter: Int = 1
        
            func reloadNearStops(nearMeter: Int) {
                
                print(nearMeter)
                readNearStopsTimeTable.fetchTimeTable(nearMeter:        getLonLatSpan(nearMeter: nearMeter), lat: (locationManager.lastLocation?.coordinate.latitude)!, lon: (locationManager.lastLocation?.coordinate.longitude)!)
            }
            
            
            func getLonLatSpan(nearMeter: Int) -> Double {
                let meters = [100,200,400,500,750,1000]
                
                if nearMeter < meters.count {
                    return Double(meters[nearMeter]) * 0.00001
                }
                else {
                    return 0.001
                }
            }
        var body: some View {
    
      
    .....
        
        ……….
        .onAppear() {
                    
                    if locationManager.lastLocation?.coordinate.longitude != nil {
                            if hasInternetConnection {
                                reloadNearStops(nearMeter: nearMeter)
                            }
                    }
        
        }}

标签： swiftswiftuiappstorage

解决方案

AppStorage不会调用函数，但onChange可以在AppStorage更改时调用函数。

struct StorageFunctionView: View {
    @AppStorage("nearMeter") var nearMeter: Int = 1
    @State var text: String = ""
    var body: some View {
        VStack{
            Text(text)
            Button("change-storage", action: {
                nearMeter = Int.random(in: 0...100)
            })
        }
        //This will listed for changes in AppStorage
        .onChange(of: nearMeter, perform: { newNearMeter in
            //Then call the function and if you need to pass the new value do it like this
            fetchSomething(value: newNearMeter)
        })
    }
    func fetchSomething(value: Int)  {
        text = "I'm fetching \(value)"
    }
}

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