如何解决从 API 调用生成视图 - SwiftUI
我是 SwiftUI 的新手,想知道是否有人可以帮助我使我的应用程序正常工作。此外,我正在尝试了解 MVVM,并想知道我是否做得正确。
应用调用 https://jsonplaceholder.typicode.com/users,我正在尝试根据 json 响应生成用户卡片。
型号:
import Foundation
// MARK: - User
class User: Codable {
let id: Int
let name,username,email: String
let address: Address
let phone,website: String
let company: Company
init(id: Int,name: String,username: String,email: String,address: Address,phone: String,website: String,company: Company) {
self.id = id
self.name = name
self.username = username
self.email = email
self.address = address
self.phone = phone
self.website = website
self.company = company
}
}
// MARK: - Address
class Address: Codable {
let street,suite,city,zipcode: String
let geo: Geo
init(street: String,suite: String,city: String,zipcode: String,geo: Geo) {
self.street = street
self.suite = suite
self.city = city
self.zipcode = zipcode
self.geo = geo
}
}
// MARK: - Geo
class Geo: Codable {
let lat,lng: String
init(lat: String,lng: String) {
self.lat = lat
self.lng = lng
}
}
// MARK: - Company
class Company: Codable {
let name,catchPhrase,bs: String
init(name: String,catchPhrase: String,bs: String) {
self.name = name
self.catchPhrase = catchPhrase
self.bs = bs
}
}
typealias Users = [User]
查看:
import SwiftUI
struct UserView: View {
let user: User
var body: some View {
vstack {
Text(user.name)
.font(.title)
.fontWeight(.bold)
Text(user.email)
.font(.callout)
.foregroundColor(.gray)
.textCase(.uppercase)
}
.frame(width: 300,height: 200,alignment: .center)
.background(Color.yellow)
.cornerRadius(10.0)
}
}
视图模型:
import SwiftUI
class Userviewmodel: ObservableObject {
@Published var users: Users = []
init() {
fetchUsers()
}
func fetchUsers() {
guard let url = URL(string: "https://jsonplaceholder.typicode.com/users") else { print("Invalid url")
return
}
let task = URLSession.shared.dataTask(with: url) { data,response,error in
guard let data = data else {
print("There was an error: \(String(describing: error?.localizedDescription))")
return
}
do {
let userData = try JSONDecoder().decode(Users.self,from: data)
print("success: \(userData.capacity)")
} catch let parsingError {
print("There was an error: \(parsingError.localizedDescription)")
}
}
task.resume()
}
}
我想在 UserContainerView 中显示它:
struct UserContainer: View {
let uservm = Userviewmodel()
var body: some View {
vstack {
Button(action: uservm.fetchUsers,label: {
Text("Fetch some users boy")
})
ForEach(uservm.users,id: \.id,content: { user in
UserView(user: user)
})
Spacer()
}
}
}
我的问题是没有显示单个 UserView,因为传递给 UserView 的 Users 数组是空的。有人能告诉我我做错了什么吗?我对这个没有把握。谢谢。
解决方法
您需要观察模型,例如
struct UserContainer: View {
@ObservedObject var uservm = UserViewModel()
并分配解析的用户,例如
do {
let userData = try JSONDecoder().decode(Users.self,from: data)
print("success: \(userData.capacity)")
DispatchQueue.main.async { [weak self] in
self?.users = userData // make sure if correct type here - cannot test
}
} catch let parsingError {
,
(选择@Asperi 遗漏的地方,因为他/她的回答将解决您的问题)
根据您的代码,这部分可能会给您带来麻烦
import SwiftUI
class UserViewModel: ObservableObject {
@Published var users: Users = []
...
}
应该是
import SwiftUI
class UserViewModel: ObservableObject {
@Published var users: [User] = []
}
并补充上一个答案,因为建议是直接投射它self?.users = userData
,因此应该进行一项调整:
let userData = try JSONDecoder().decode([Users].self,from: data)
唯一的变化是您将其解码为一个数组,因为这是您选择的发布者在您的 viewModel 中的内容。
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