swift - URL 验证发布者
问题描述
我正在尝试在带有组合的 Swift 中编写一个 URL 验证器,并让一个 SwiftUI 视图订阅它。它似乎在模拟器中工作正常,但在我的开发手机上崩溃(运行 13.1)。
场景...用户输入一个 UITextField,它连接到视图模型中的 urlString var。当发生变化时,我清理字符串,创建一个 URL,然后使用 URLSession 进行 HEAD 测试。这一切都在 sim 中有效,但点击设备上的文本字段会使应用程序崩溃,我没有得到任何好的堆栈跟踪。有任何想法吗?
static func testURLPublisher(string: String) -> AnyPublisher<URL?, Never> {
let validatedURL = try? validateURL(string: string)
guard let urlToCheck = validatedURL else {
return Just(nil).eraseToAnyPublisher()
}
var request = URLRequest(url: urlToCheck)
request.httpMethod = "HEAD"
let publisher = URLSession.shared.dataTaskPublisher(for: request)
.handleEvents(receiveSubscription: { _ in
networkActivityPublisher.send(true)
}, receiveCompletion: { _ in
networkActivityPublisher.send(false)
}, receiveCancel: {
networkActivityPublisher.send(false)
})
.tryMap { data, response -> URL? in
// URL Responded - Check Status Code
guard let urlResponse = response as? HTTPURLResponse, ((urlResponse.statusCode >= 200 && urlResponse.statusCode < 400) || urlResponse.statusCode == 405) else {
throw URLValidatorError.serverError("Could not find the a servr at: \(urlToCheck)")
}
return urlResponse.url?.absoluteURL
}
.catch { err in
return Just(nil)
}
.eraseToAnyPublisher()
return publisher
}
使用它的视图看起来像这样......
class NewSiteViewModel: ObservableObject {
@Published var validatedURL: URL?
//@Published var secretKey: String?
@Published var urlString: String = ""
@Published var isValidURL: Bool = false
private var cancellable = Set<AnyCancellable>()
init() {
$urlString
.dropFirst(1)
.throttle(for: 0.5, scheduler: DispatchQueue(label: "Validator"), latest: true)
.removeDuplicates()
.compactMap { string -> AnyPublisher<URL?, Never> in
return URL.testURLPublisher(string: string)
}
.switchToLatest()
.receive(on: RunLoop.main)
.sink { recievedURL in
guard let url = recievedURL else {
self.validatedURL = nil
self.isValidURL = false
return
}
self.validatedURL = url
self.isValidURL = true
}
.store(in: &cancellable)
}
}
解决方案
13.1beta4 不像.throttle
13.0 中的早期实现那样实现。现在DispatchQueue("..")
作为参数在该行上崩溃,没有任何可用的错误文本。一个有效的论点是RunLoop.main
。
它在这里工作。您可能必须按照传输安全性已阻止明文 HTTPAllow arbitrary Loads
中所述添加到您的. 它可能不会在 中强制执行,但肯定是在设备上。info.plist
Simulator
您可以NSExceptionDomains
省略 - 部分。
使用 .throttle 参数的示例
import SwiftUI
import Combine
struct URLTesterView: View {
@ObservedObject var model = NewSiteViewModel()
@State var networkActivity = false
var body: some View {
VStack{
TextField("url string", text: $model.urlString)
Text("Is valid: \(model.isValidURL ? "true" : "false")")
Text("Validated URL: \(model.validatedURL?.absoluteString ?? "")")
Text("Network activity: \(networkActivity ? "true" : "false")")
}.onReceive(networkActivityPublisher
.receive(on: DispatchQueue.main)) {
self.networkActivity = $0
}
}
}
class NewSiteViewModel: ObservableObject {
@Published var validatedURL: URL?
//@Published var secretKey: String?
@Published var urlString: String = ""
@Published var isValidURL: Bool = false
private var cancellable = Set<AnyCancellable>()
init() {
$urlString
.dropFirst(1)
.throttle(for: 0.5, scheduler: RunLoop.main, latest: true)
.removeDuplicates()
.compactMap { string -> AnyPublisher<URL?, Never> in
return URL.testURLPublisher(string: string)
}
.switchToLatest()
.receive(on: RunLoop.main)
.sink { recievedURL in
guard let url = recievedURL else {
self.validatedURL = nil
self.isValidURL = false
return
}
self.validatedURL = url
self.isValidURL = true
}
.store(in: &cancellable)
}
}
func validateURL(string: String) throws -> URL {
guard let url = URL(string: string) else {
throw URLValidatorError.urlIsInvalid(string)
}
return url
}
let networkActivityPublisher = PassthroughSubject<Bool, Never>()
enum URLValidatorError: Error {
case serverError(_ string: String)
case urlIsInvalid(_ string: String)
}
extension URL {
static func testURLPublisher(string: String) -> AnyPublisher<URL?, Never> {
let validatedURL = try? validateURL(string: string)
guard let urlToCheck = validatedURL else {
return Just(nil).eraseToAnyPublisher()
}
var request = URLRequest(url: urlToCheck)
request.httpMethod = "HEAD"
let publisher = URLSession.shared.dataTaskPublisher(for: request)
.handleEvents(receiveSubscription: { _ in
networkActivityPublisher.send(true)
}, receiveCompletion: { _ in
networkActivityPublisher.send(false)
}, receiveCancel: {
networkActivityPublisher.send(false)
})
.tryMap { data, response -> URL? in
// URL Responded - Check Status Code
guard let urlResponse = response as? HTTPURLResponse, ((urlResponse.statusCode >= 200 && urlResponse.statusCode < 400) || urlResponse.statusCode == 405) else {
throw URLValidatorError.serverError("Could not find the a servr at: \(urlToCheck)")
}
return urlResponse.url?.absoluteURL
}
.catch { err in
return Just(nil)
}
.eraseToAnyPublisher()
return publisher
}
}
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