错误：传递给不带参数 SwiftUI 的调用的参数

Posted 2023-03-07

【中文标题】错误：传递给不带参数 SwiftUI 的调用的参数

【英文标题】：Error: Argument passed to call that takes no arguments SwiftUI

【发布时间】：2020-10-30 14:42:06

【问题描述】：

在我的代码中，我收到了这个错误，我不知道如何解决它。错误在尾随代码块中

struct Map: View 
    
    @ObservedObject public var dataManager = DataManager.shared
    
    @Binding public var seqId: String
    
    // rz- to pass seqId to second view
    //   @State public var seqId2: String = ""
    
    var body: some View 
        
        ZStack 
            VStack 
                Text("Results").foregroundColor(Color.white).onAppearself.dataManager.downloadSeqData(seqId: self.seqId)                        .onAppear(perform: playSound)/*rz want to add this sound func to contentview somehow, otherwise it will constantly play sound when page loads */ .edgesIgnoringSafeArea(.all)
                
                //rz- if strand is linear draw line
                if dataManager.dataSet?.INSDSeq.topology == "linear" 
                    
                Rectangle()
                    .fill(Color.black)
                    .frame(width: 500, height: 20)
                
                //rz- if strand is circular draw o
                if dataManager.dataSet?.INSDSeq.topology == "circular" 
                Circle()
                    .stroke(Color.black, style: StrokeStyle(lineWidth: 20, lineCap: .round, lineJoin: .round))
                    .frame(width: 500, height: 500)
                
                if dataManager.dataSet?.INSDSeq.topology != "circular" && dataManager.dataSet?.INSDSeq.topology != "linear"
                    Text("Data Unavailable, try a new accession number.")
                
            
                
            .navigationBarItems(
    //rz - added home and genbank view to navigation bars
                leading:
                    NavigationLink(destination: ContentView()) 
                           Text("New Query")
                               .font(.title)
                               .foregroundColor(Color.black)
                        ,

                trailing:
                    NavigationLink(destination: Screen(seqId: self.$seqId)) 
                      Text("GenBank View")
                          .font(.title)
                          .foregroundColor(Color.black)

错误在$seqId

NavigationLink(destination: Screen(seqId: self.$seqId)) 

这是屏幕视图

import SwiftUI


struct Screen: View 


@ObservedObject public var dataManager = DataManager.shared
@State private var seqId: String = ""

var body: some View 
    VStack 
       TextField("Enter Accession Number", text: $seqId)
        .padding()
        
        Button("Search")
        
        dataManager.downloadSeqData(seqId: seqId)
            
            
           
        
        
        ScrollView 

        VStack(alignment: .leading) 
           
                    
                Text(dataManager.dataSet?.INSDSeq.locus ?? "")
                    .padding()
                Text(dataManager.dataSet?.INSDSeq.organism ?? "").padding()
                Text(dataManager.dataSet?.INSDSeq.source ?? "").padding()
                Text(dataManager.dataSet?.INSDSeq.taxonomy ?? "").padding()
                Text(dataManager.dataSet?.INSDSeq.topology ?? "").padding()
                Text(dataManager.dataSet?.INSDSeq.length == nil ? "" : "\(dataManager.dataSet!.INSDSeq.length)") .padding()
                Text(dataManager.dataSet?.INSDSeq.strandedness ?? "").padding()
                Text(dataManager.dataSet?.INSDSeq.moltype ?? "").padding()
                Text(dataManager.dataSet?.INSDSeq.sequence ?? "").padding()
            
            
            
            .cornerRadius(10)
            
            VStack(alignment: .leading, spacing: 10) 
                ForEach(dataManager.featureList, id:\.self)  feature in
                    
                    VStack (alignment: .leading)
                        VStack (alignment: .leading) 
                            Text(feature.INSDFeature_key).bold()
                            Text(feature.INSDFeature_location)
                        .padding()
                    
                        IntervalSection(feature: feature)
                        
                        QualsSection(feature: feature)
                        
                    
                    .cornerRadius(10)
                
            
            
            .cornerRadius(20)
        
        .padding(.horizontal)
                    
    
    
    
    
    



struct IntervalSection: View 
var feature: INSDFeature
var body: some View 
    VStack (alignment: .leading)
        ForEach(0..<feature.INSDFeature_intervals.count, id: \.self)  i in
            ForEach(0..<feature.INSDFeature_intervals[i].INSDInterval.count, id: \.self)  j in
                if let from = feature.INSDFeature_intervals[i].INSDInterval[j].INSDInterval_from 
                    VStack (alignment: .leading)
                        Text("\(from)").bold()
                        Text("\(feature.INSDFeature_intervals[i].INSDInterval[j].INSDInterval_to ?? -1)")
                    
                    .padding()
                    .cornerRadius(10)
                
            
        
    



struct QualsSection: View
var feature: INSDFeature
var body: some View 
    VStack (alignment: .leading)
        ForEach(0..<feature.INSDFeature_quals.count , id: \.self)  i in
            ForEach(0..<feature.INSDFeature_quals[i].INSDQualifier.count , id: \.self)  j in
                VStack (alignment: .leading)
                    Text(feature.INSDFeature_quals[i].INSDQualifier[j].INSDQualifier_name).bold()
                    Text(feature.INSDFeature_quals[i].INSDQualifier[j].INSDQualifier_value)
                
                .padding()
                .cornerRadius(10)
            
        
    

【问题讨论】：

Screen 是什么？对于Screen，init 方法是什么样的？很可能你没有这样的 init。

Screen 是以列表格式显示信息的内容视图。屏幕页面中没有init方法

贴代码太麻烦？它有什么属性，如果它是一个我认为是的结构，总是有一个合成的 init。

刚刚上传了

并且视图不采用 seqId 作为参数，因为该属性是私有的（并且是 @State 变量）。在我看来，屏幕视图不需要用 seqId 初始化，因为它将它作为输入？否则你需要将其更改为@Binding 并删除私有

【参考方案1】：

在 SwiftUI 中，如果数据来自另一个视图，则应使用 Binding 而不是 State。此外，Screen 的两个属性都是私有的，因此在这种情况下无法从结构本身的外部访问它们。

我建议将Screen 中的seqID 公开，就像您使用dataManager 所做的那样，并将其更改为State