类型“ContentView”不符合协议“View”（Xcode - Swift UI）

Posted 2023-02-24

【中文标题】类型“ContentView”不符合协议“View”（Xcode - Swift UI）

【英文标题】：Type 'ContentView' does not conform to protocol 'View' (Xcode - Swift UI)

【发布时间】：2021-01-05 13:40:48

【问题描述】：

我尝试在 ContentView(Swift UI) 中为我的应用程序实现 ,,Face ID" 功能，但之后我收到此错误 - "Type 'ContentView' does not conform to protocol 'View'"。当我尝试修复时它提供的错误解决方案：typealias Body = <#type#> 但我不知道该放什么。也许我只是以错误的方式实现了 Face ID，所以这里是结果代码源和实现之前的代码源。

之后：

import SwiftUI
import LocalAuthentication

struct ContentView : View 
    
    
    @State private var isUnlocked = false
    @ObservedObject var service: DataService = .shared
    
    var categories:[String:[Goal]] 
        .init(
            grouping: service.goals,
            by: $0.category.rawValue
        )
    
    
    func authenticate() 
        let context = LAContext()
        var error: NSError?

        // check whether biometric authentication is possible
        if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) 
            // it's possible, so go ahead and use it
            let reason = "We need to unlock your data."

            context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason)  success, authenticationError in
                // authentication has now completed
                DispatchQueue.main.async 
                    if success 
                        self.isUnlocked = true
                     else 
                        // there was a problem               
                
                
    
    var body: some View 
        VStack 
            if self.isUnlocked 
        NavigationView
            List (categories.keys.sorted(), id:\.self) key in
                GoalRow(categoryName: "Level \(key)".uppercased(), goals: self.categories[key]!)
                    .frame(height: 320)
                .padding(.top)
                .padding(.bottom)
            
            .navigationBarTitle(Text("Future"))
        
             else 
                Text("Locked")
            
        
        .onAppear(perform: authenticate)
  


#if DEBUG
struct Content_Previews : PreviewProvider 
    static var previews: some View 
        ContentView()
    

#endif
        
    

之前：

import SwiftUI

struct ContentView : View 
    
    @ObservedObject var service: DataService = .shared
    
    var categories:[String:[Goal]] 
        .init(
            grouping: service.goals,
            by:  $0.category.rawValue 
        )
    
    
    
    var body: some View 
        NavigationView
            List (categories.keys.sorted(), id:\.self) key in
                GoalRow(categoryName: "Level \(key)".uppercased(), goals: self.categories[key]!)
                    .frame(height: 320)
                .padding(.top)
                .padding(.bottom)
            
            .navigationBarTitle(Text("Future"))
        
    



#if DEBUG
struct Content_Previews : PreviewProvider 
    static var previews: some View 
        ContentView()
    

#endif

【参考方案1】：

首先，选择所有代码并按cmd+i 进行代码缩进。 在代码中，您在代码末尾关闭了 3 个大括号，这是不正确的。添加这 3 个大括号用于身份验证功能。

struct ContentView : View     
    @State private var isUnlocked = false
    @ObservedObject var service: DataService = .shared
    
    var categories:[String:[Goal]] 
        .init(
            grouping: service.goals,
            by: $0.category.rawValue
        )
    
    
    func authenticate() 
        let context = LAContext()
        var error: NSError?
        
        // check whether biometric authentication is possible
        if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) 
            // it's possible, so go ahead and use it
            let reason = "We need to unlock your data."
            
            context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason)  success, authenticationError in
                // authentication has now completed
                DispatchQueue.main.async 
                    if success 
                        self.isUnlocked = true
                     else 
                        // there was a problem
                    
                
            
        
    
    
    
    //Your body view


#if DEBUG
struct Content_Previews : PreviewProvider 
    static var previews: some View 
        ContentView()
    

#endif

【讨论】：

谢谢伙计！现在按我的意愿工作