无法构造委托,因为它没有可访问的初始值设定项?
Delegate cannot be constructed because it has no accessible initializers?
所以我有一个 class 具有发送 SMS 消息的功能。我尝试使 class 符合委托协议...它最终导致 class 需要一个类型别名,我认为它是 MFMessageViewController 类型,但没有用
class functions: NSObject, ObservableObject, MFMessageComposeViewControllerDelegate {
func sendInviteMessage(number: String) {
if MFMessageComposeViewController.canSendText() {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = self
message.recipients = [number]
message.body = "Hi, I'd like to invite you to join my app google.com"
message.present(message, animated: true)
}
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true)
}
}
我认为您应该看一看 here 以更深入地了解 swift 中的委派和协议。您无法实例化协议 - 您需要一个符合该协议的 class 来完成您想要的。
我认为你的 class 应该是这样的:
class functions: NSObject, ObservableObject, MFMessageComposeViewControllerDelegate {
func sendInviteMessage() {
if MFMessageComposeViewController.canSendText() {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = self
message.recipients = ["##########"]
message.body = "Hi, I'd like to invite you to join my app google.com"
// here we have a problem - You will need a ViewController or something that presents the MessageComposeViewController "message" --> It cannot present itself
//message.present(message, animated: true)
}
}
func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
controller.dismiss(animated: true)
}
}
演示解决方案的外观在很大程度上取决于您的需求。 (IMO 这段代码应该放在 UIViewController
)
如果有帮助请告诉我!
如果你的项目使用 SwiftUI 那么你可以使用 UIViewControllerRepresentable
struct MessageComposeViewController: UIViewControllerRepresentable {
var toRecipients: [String]
var messageBody: String
var didFinish: ()->()
func makeCoordinator() -> Coordinator {
return Coordinator(self)
}
func makeUIViewController(context: UIViewControllerRepresentableContext<MessageComposeViewController>) -> MFMessageComposeViewController {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = context.coordinator
message.recipients = self.toRecipients
message.body = self.messageBody
return message
}
final class Coordinator: NSObject, MFMessageComposeViewControllerDelegate {
var parent: MessageComposeViewController
init(_ controller: MessageComposeViewController) {
self.parent = controller
}
func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
parent.didFinish()
controller.dismiss(animated: true)
}
}
func updateUIViewController(_ uiViewController: MFMessageComposeViewController, context: UIViewControllerRepresentableContext<MessageComposeViewController>) {
}
}
用法:
struct MessageView: View {
@State private var showingMessage = false
var body: some View {
VStack {
Button("Open Message") {
self.showingMessage.toggle()
}
}
.sheet(isPresented: $showingMessage) {
MessageComposeViewController(toRecipients: ["1234567890"], messageBody: "Hi, I'd like to invite you to join my app google.com") {
// Did finish action
}
}
}
}
可能的另一种解决方案。您可以创建一个单例 class 并在根控制器上呈现 MFMessageComposeViewController。
像这样
class Functions: NSObject, MFMessageComposeViewControllerDelegate {
static let shared = Functions()
func sendInviteMessage(number: String) {
if MFMessageComposeViewController.canSendText() {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = self
message.recipients = [number]
message.body = "Hi, I'd like to invite you to join my app google.com"
UIApplication.shared.windows.first?.rootViewController?.present(message, animated: true)
}
}
func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
controller.dismiss(animated: true)
}
}
用法:
struct MessageView: View {
var body: some View {
Button("Open Message") {
Functions.shared.sendInviteMessage(number: "12345678")
}
}
}
所以我有一个 class 具有发送 SMS 消息的功能。我尝试使 class 符合委托协议...它最终导致 class 需要一个类型别名,我认为它是 MFMessageViewController 类型,但没有用
class functions: NSObject, ObservableObject, MFMessageComposeViewControllerDelegate {
func sendInviteMessage(number: String) {
if MFMessageComposeViewController.canSendText() {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = self
message.recipients = [number]
message.body = "Hi, I'd like to invite you to join my app google.com"
message.present(message, animated: true)
}
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true)
}
}
我认为您应该看一看 here 以更深入地了解 swift 中的委派和协议。您无法实例化协议 - 您需要一个符合该协议的 class 来完成您想要的。
我认为你的 class 应该是这样的:
class functions: NSObject, ObservableObject, MFMessageComposeViewControllerDelegate {
func sendInviteMessage() {
if MFMessageComposeViewController.canSendText() {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = self
message.recipients = ["##########"]
message.body = "Hi, I'd like to invite you to join my app google.com"
// here we have a problem - You will need a ViewController or something that presents the MessageComposeViewController "message" --> It cannot present itself
//message.present(message, animated: true)
}
}
func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
controller.dismiss(animated: true)
}
}
演示解决方案的外观在很大程度上取决于您的需求。 (IMO 这段代码应该放在 UIViewController
)
如果有帮助请告诉我!
如果你的项目使用 SwiftUI 那么你可以使用 UIViewControllerRepresentable
struct MessageComposeViewController: UIViewControllerRepresentable {
var toRecipients: [String]
var messageBody: String
var didFinish: ()->()
func makeCoordinator() -> Coordinator {
return Coordinator(self)
}
func makeUIViewController(context: UIViewControllerRepresentableContext<MessageComposeViewController>) -> MFMessageComposeViewController {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = context.coordinator
message.recipients = self.toRecipients
message.body = self.messageBody
return message
}
final class Coordinator: NSObject, MFMessageComposeViewControllerDelegate {
var parent: MessageComposeViewController
init(_ controller: MessageComposeViewController) {
self.parent = controller
}
func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
parent.didFinish()
controller.dismiss(animated: true)
}
}
func updateUIViewController(_ uiViewController: MFMessageComposeViewController, context: UIViewControllerRepresentableContext<MessageComposeViewController>) {
}
}
用法:
struct MessageView: View {
@State private var showingMessage = false
var body: some View {
VStack {
Button("Open Message") {
self.showingMessage.toggle()
}
}
.sheet(isPresented: $showingMessage) {
MessageComposeViewController(toRecipients: ["1234567890"], messageBody: "Hi, I'd like to invite you to join my app google.com") {
// Did finish action
}
}
}
}
可能的另一种解决方案。您可以创建一个单例 class 并在根控制器上呈现 MFMessageComposeViewController。 像这样
class Functions: NSObject, MFMessageComposeViewControllerDelegate {
static let shared = Functions()
func sendInviteMessage(number: String) {
if MFMessageComposeViewController.canSendText() {
let message = MFMessageComposeViewController()
message.messageComposeDelegate = self
message.recipients = [number]
message.body = "Hi, I'd like to invite you to join my app google.com"
UIApplication.shared.windows.first?.rootViewController?.present(message, animated: true)
}
}
func messageComposeViewController(_ controller: MFMessageComposeViewController, didFinishWith result: MessageComposeResult) {
controller.dismiss(animated: true)
}
}
用法:
struct MessageView: View {
var body: some View {
Button("Open Message") {
Functions.shared.sendInviteMessage(number: "12345678")
}
}
}