swift - 类型“ContentView”不符合协议“View”(Xcode - Swift UI)
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'"。当我尝试修复错误时提供解决方案: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。
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
}
}
}
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
解决方案
首先,选择所有代码并按cmd+i
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
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