我在SwiftUI中观察到对象有问题。我可以在View结构上看到更改的观察对象值。但是,在类或函数中,即使更改了TextField(可观察的对象)的文本值,但“ self.codeTwo.text仍然没有更改。
这是我的代码示例(这是我的ObservableObject)
class settingCodeTwo: ObservableObject {
private static let userDefaultTextKey = "textKey2"
@Published var text: String = UserDefaults.standard.string(forKey: settingCodeTwo.userDefaultTextKey) ?? ""
private var canc: AnyCancellable!
init() {
canc = $text.debounce(for: 0.2, scheduler: DispatchQueue.main).sink { newText in
UserDefaults.standard.set(newText, forKey: settingCodeTwo.userDefaultTextKey)
}
}
deinit {
canc.cancel()
}
}
而主要的问题是...“ self.codeTwo.text”从未改变!
class NetworkManager: ObservableObject {
@ObservedObject var codeTwo = settingCodeTwo()
@Published var posts = [Post]()
func fetchData() {
var urlComponents = URLComponents()
urlComponents.scheme = "http"
urlComponents.host = "\(self.codeTwo.text)" //This one I want to use observable object
urlComponents.path = "/mob_json/mob_json.aspx"
urlComponents.queryItems = [
URLQueryItem(name: "nm_sp", value: "UP_MOB_CHECK_LOGIN"),
URLQueryItem(name: "param", value: "1000|1000|\(Gpass.hahaha)")
]
if let url = urlComponents.url {
print(url)
let session = URLSession(configuration: .default)
let task = session.dataTask(with: url) { (data, response, error) in
if error == nil {
let decoder = JSONDecoder()
if let safeData = data {
do {
let results = try decoder.decode(Results.self, from: safeData)
DispatchQueue.main.async {
self.posts = results.Table
}
} catch {
print(error)
}
}
}
}
task.resume()
}
}
}
这是一种观点,我可以抓住这一点的价值变化
import SwiftUI
import Combine
struct SettingView: View {
@ObservedObject var codeTwo = settingCodeTwo()
var body: some View {
ZStack {
Rectangle().foregroundColor(Color.white).edgesIgnoringSafeArea(.all).background(Color.white)
VStack {
TextField("test", text: $codeTwo.text).textFieldStyle(BottomLineTextFieldStyle()).foregroundColor(.blue)
Text(codeTwo.text)
}
}
}
}
请帮帮我。
它使用的两个不同实例SettingCodeTwo
-在中的NetworkNamager
另一个实例SettingsView
,因此如果同时创建它们,则不会同步。
这是一种使这两个实例保持自我同步的方法(这可能是因为它们使用相同的存储- UserDefaults
)
经过Xcode 11.4 / iOS 13.4测试
下面的修改后的代码(另请参见重要的内联注释)
extension UserDefaults {
@objc dynamic var textKey2: String { // helper keypath
return string(forKey: "textKey2") ?? ""
}
}
class SettingCodeTwo: ObservableObject { // use capitalised name for class !!!
private static let userDefaultTextKey = "textKey2"
@Published var text: String = UserDefaults.standard.string(forKey: SettingCodeTwo.userDefaultTextKey) ?? ""
private var canc: AnyCancellable!
private var observer: NSKeyValueObservation!
init() {
canc = $text.debounce(for: 0.2, scheduler: DispatchQueue.main).sink { newText in
UserDefaults.standard.set(newText, forKey: SettingCodeTwo.userDefaultTextKey)
}
observer = UserDefaults.standard.observe(\.textKey2, options: [.new]) { _, value in
if let newValue = value.newValue, self.text != newValue { // << avoid cycling on changed self
self.text = newValue
}
}
}
}
class NetworkManager: ObservableObject {
var codeTwo = SettingCodeTwo() // no @ObservedObject needed here
...
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