我是Combine and Sink的新手，但是我放入其中的打印似乎没有记录下来，但是随着在AWS Amplify中创建用户，操作的结果完成了。
@objc private func createAccountButtonAction(sender: UIButton) {
print("Create Account Button Action")
signUp(password: self.password, email: self.email)
}
func signUp(password: String, email: String) -> AnyCancellable {
let userAttributes = [AuthUserAttribute(.email, value: email)]
let options = AuthSignUpRequest.Options(userAttributes: userAttributes)
let sink = Amplify.Auth.signUp(username: email, password: password, options: options)
.resultPublisher.sink(receiveCompletion: { (authError) in
print("Failed with error: \(authError)")
}, receiveValue: { (signUpResult) in
print("Signed Up")
})
return sink
}
使用.sink运算符时，它返回类型为的令牌AnyCancellable。当该令牌被销毁时，它会cancel自行调用，这会破坏它所代表的订阅。您没有保存令牌，因此Swift会在订阅有机会提供任何输出之前立即销毁它。
通常的解决方案是找到存储令牌的位置，例如在控制器对象的属性中：
class AccountCreationController: UIViewController {
private var token: AnyCancellable? = nil
// NEW ^^^^^ storage for the AnyCancellable
@objc private func createAccountButtonAction(sender: UIButton) {
print("Create Account Button Action")
signUp(password: self.password, email: self.email)
}
func signUp(password: String, email: String) {
let userAttributes = [AuthUserAttribute(.email, value: email)]
let options = AuthSignUpRequest.Options(userAttributes: userAttributes)
token = Amplify.Auth.signUp(username: email, password: password, options: options)
// NEW ^^^^^ store the AnyCancellable to keep the subscription alive
.resultPublisher.sink(
receiveCompletion: { (authError) in
print("Failed with error: \(authError)")
},
receiveValue: { (signUpResult) in
print("Signed Up")
})
}
}
另一种，如果你确信你永远要取消订阅（例如，用户不能按下“取消”按钮，背出），是创建一个Subscribers.Sink直接，而是采用sink操作，并使用subscribe方法来认购Sink到的Publisher。该subscribe方法并没有返回AnyCancellable。该Sink对象本身是一个Cancellable，但不是AnyCancellable，并且您不必将其存储在任何地方以保持订阅有效。
class AccountCreationController: UIViewController {
@objc private func createAccountButtonAction(sender: UIButton) {
print("Create Account Button Action")
signUp(password: self.password, email: self.email)
}
func signUp(password: String, email: String) {
let userAttributes = [AuthUserAttribute(.email, value: email)]
let options = AuthSignUpRequest.Options(userAttributes: userAttributes)
Amplify.Auth.signUp(username: email, password: password, options: options)
// NEW ^ There is no AnyCancellable to store.
.resultPublisher
.subscribe(
// NEW ^^^^^^^^^^ use the subscribe method instead of sink.
Subscribers.Sink(
// NEW ^^^^^^^^^^^^^^^^ Create a Sink object.
receiveCompletion: { (authError) in
print("Failed with error: \(authError)")
},
receiveValue: { (signUpResult) in
print("Signed Up")
}
)
)
}
}
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我来说两句