编辑：
非常感谢Paulw11帮助我解决这个问题。我在这里添加了完整的代码，以便于重用：
类：
import UIKit
import MessageUI
struct Feedback {
let recipients: [String]
let subject: String
let body: String
let footer: String
}
class FeedbackManager: NSObject, MFMailComposeViewControllerDelegate {
private var feedback: Feedback
private var completion: ((Result<MFMailComposeResult,Error>)->Void)?
override init() {
fatalError("Use FeedbackManager(feedback:)")
}
init?(feedback: Feedback) {
guard MFMailComposeViewController.canSendMail() else {
return nil
}
self.feedback = feedback
}
func send(on viewController: UIViewController, completion:(@escaping(Result<MFMailComposeResult,Error>)->Void)) {
let mailVC = MFMailComposeViewController()
self.completion = completion
mailVC.mailComposeDelegate = self
mailVC.setToRecipients(feedback.recipients)
mailVC.setSubject(feedback.subject)
mailVC.setMessageBody("<p>(feedback.body)<br><br><br><br><br>(feedback.footer)</p>", isHTML: true)
viewController.present(mailVC, animated:true)
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
if let error = error {
completion?(.failure(error))
controller.dismiss(animated: true)
} else {
completion?(.success(result))
controller.dismiss(animated: true)
}
}
}
在视图控制器中：
添加变量：
var feedbackManager: FeedbackManager?
用：
let feedback = Feedback(recipients: "String", subject: "String", body: "Body", footer: "String")
if let feedManager = FeedbackManager(feedback: feedback) {
self.feedbackManager = feedManager
self.feedbackManager?.send(on: self) { [weak self] result in
switch result {
case .failure(let error):
print("error: ", error.localizedDescription)
// Do something with the error
case .success(let mailResult):
print("Success")
// Do something with the result
}
self?.feedbackManager = nil
}
} else { // Cant Send Email: // Added UI Alert:
let failedMenu = UIAlertController(title: "String", message: nil, preferredStyle: .alert)
let okAlert = UIAlertAction(title: "String", style: .default)
failedMenu.addAction(okAlert)
present(failedMenu, animated: true)
}
我正在尝试创建一个类来处理初始化MFMailComposeViewController以在应用程序内发送电子邮件。
我在使其工作时遇到问题。好吧，如果它不起作用，宁愿让它不会崩溃。
.class：
import UIKit
import MessageUI
struct Feedback {
let recipients = "String"
let subject: String
let body: String
}
class FeedbackManager: MFMailComposeViewController, MFMailComposeViewControllerDelegate {
func sendEmail(feedback: Feedback) {
if MFMailComposeViewController.canSendMail() {
self.mailComposeDelegate = self
self.setToRecipients([feedback.recipients])
self.setSubject("Feedback: (feedback.subject)")
self.setMessageBody("<p>(feedback.body)</p>", isHTML: true)
} else {
print("else:")
mailFailed()
}
}
func mailFailed() {
print("mailFailed():")
let failedMenu = UIAlertController(title: "Please Email Me!", message: nil, preferredStyle: .alert)
let okAlert = UIAlertAction(title: "Ok!", style: .default)
failedMenu.addAction(okAlert)
self.present(failedMenu, animated: true, completion: nil)
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true)
}
}
然后从不同的视图控制器调用它：
let feedbackManager = FeedbackManager()
feedbackManager.sendEmail(feedback: Feedback(subject: "String", body: "String"))
self.present(feedbackManager, animated: true, completion: nil)
tableView.deselectRow(at: indexPath, animated: true)
如果MFMailComposeViewController.canSendMail(( == true，则上述工作正常。我面临的问题是，如果canSendMail((不为真，那么该类显然无法初始化并崩溃。这是有道理的。
错误：
Unable to initialize due to + [MFMailComposeViewController canSendMail] returns NO.
我不确定从这里开始如何让它工作。我尝试将FeedbackManager从MFMailComposeViewController更改为UIViewController。这似乎有效，但由于它在堆栈上添加了视图，因此会导致奇怪的图形显示。
我可以做的另一件事是导入 MessageUI，并为我希望能够发送电子邮件的每个控制器遵守 MFMailComposeViewController。这样我就可以在尝试初始化 FeedbackManager(( 之前检查 canSendMail((。但这似乎也不是最好的答案。
我还能如何让它工作？
编辑： 我已经得到了使用它的代码，但是，在呈现MFMailComposeViewController之前，将视图添加到堆栈上有一个丑陋的过渡。
class FeedbackManager: UIViewController, MFMailComposeViewControllerDelegate {
func sendEmail(feedback: Feedback, presentingViewController: UIViewController) -> UIViewController {
if MFMailComposeViewController.canSendMail() {
let mail = MFMailComposeViewController()
mail.mailComposeDelegate = self
mail.setToRecipients([feedback.recipients])
mail.setSubject("Feedback: (feedback.subject)")
mail.setMessageBody("<p>(feedback.body)</p>", isHTML: true)
present(mail, animated: true)
return self
} else {
print("else:")
return mailFailed(presentingViewController: presentingViewController)
}
}
func mailFailed(presentingViewController: UIViewController) -> UIViewController {
print("mailFailed():")
let failedMenu = UIAlertController(title: "Please Email Me!", message: nil, preferredStyle: .alert)
let okAlert = UIAlertAction(title: "Ok!", style: .default)
failedMenu.addAction(okAlert)
return failedMenu
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true)
self.dismiss(animated: false)
}
}
子类化MFMailComposeViewController是错误的方法。 此类旨在"按原样"使用。 如果您愿意，可以构建包装类：
struct Feedback {
let recipients = "String"
let subject: String
let body: String
}
class FeedbackManager: NSObject, MFMailComposeViewControllerDelegate {
private var feedback: Feedback
private var completion: ((Result<MFMailComposeResult,Error>)->Void)?
override init() {
fatalError("Use FeedbackManager(feedback:)")
}
init?(feedback: Feedback) {
guard MFMailComposeViewController.canSendMail() else {
return nil
}
self.feedback = feedback
}
func send(on viewController: UIViewController, completion:(@escaping(Result<MFMailComposeResult,Error>)->Void)) {
let mailVC = MFMailComposeViewController()
self.completion = completion
mailVC.mailComposeDelegate = self
mailVC.setToRecipients([feedback.recipients])
mailVC.setSubject("Feedback: (feedback.subject)")
mailVC.setMessageBody("<p>(feedback.body)</p>", isHTML: true)
viewController.present(mailVC, animated:true)
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
if let error = error {
completion?(.failure(error))
} else {
completion?(.success(result))
}
}
}
然后从视图控制器使用它：
let feedback = Feedback(subject: "String", body: "Body")
if let feedbackMgr = FeedbackManager(feedback: feedback) {
self.feedbackManager = feedbackMgr
feedback.send(on: self) { [weak self], result in
switch result {
case .failure(let error):
// Do something with the error
case .success(let mailResult):
// Do something with the result
}
self.feedbackManager = nil
}
} else {
// Can't send email
}
您需要在属性中保留对FeedbackManager的强引用，否则它将在包含函数退出后立即释放。 我上面的代码引用了一个属性
var feedbackManager: FeedbackManager?
虽然这将起作用，但更好的用户体验是，如果您直接检查canSendMail并禁用/隐藏允许他们发送反馈的 UI 组件
通过首先添加一个检查 .canSendMail 是否为 true 的类来解决此问题。如果是，则它点击邮政发送类以显示 MFMailComposeViewController。
这是我提出的唯一解决方法，允许MFMailComposeViewController成为它自己的MFMailComposeViewControllerDelegate。同时还可以防止崩溃，如果.canSendMail = false。
import UIKit
import MessageUI
struct Feedback {
let recipients = ["Strings"]
let subject: String
let body: String
}
class FeedbackManager {
func tryMail() -> Bool {
if MFMailComposeViewController.canSendMail() {
return true
} else {
return false
}
}
func mailFailed() -> UIViewController {
let failedMenu = UIAlertController(title: "Please Email Me!", message: nil, preferredStyle: .alert)
let okAlert = UIAlertAction(title: "Ok!", style: .default)
failedMenu.addAction(okAlert)
return failedMenu
}
}
class PostalManager: MFMailComposeViewController, MFMailComposeViewControllerDelegate {
func sendEmail(feedback: Feedback) -> MFMailComposeViewController {
if MFMailComposeViewController.canSendMail() {
self.mailComposeDelegate = self
self.setToRecipients(feedback.recipients)
self.setSubject("Feedback: (feedback.subject)")
self.setMessageBody("<p>(feedback.body)</p>", isHTML: true)
}
return self
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true)
}
}
调用者：
let feedbackManager = FeedbackManager()
let feedback = Feedback(subject: "String", body: "Body")
switch feedbackManager.tryMail() {
case true:
let postalManager = PostalManager()
present(postalManager.sendEmail(feedback: feedback), animated: true)
case false:
present(feedbackManager.mailFailed(), animated: true)
}
您可以按如下方式更改代码。
struct Feedback {
let recipients = "String"
let subject: String
let body: String
}
class FeedbackManager: NSObject, MFMailComposeViewControllerDelegate {
func sendEmail(presentingViewController: UIViewController)) {
if MFMailComposeViewController.canSendMail() {
let mail = MFMailComposeViewController()
mail.mailComposeDelegate = self
mail.setToRecipients([feedback.recipients])
mail.setSubject("Feedback: (feedback.subject)")
mail.setMessageBody("<p>(feedback.body)</p>", isHTML: true)
presentingViewController.present(mail, animated: true)
} else {
print("else:")
mailFailed(presentingViewController: presentingViewController)
}
}
func mailFailed(presentingViewController: UIViewController) {
print("mailFailed():")
let failedMenu = UIAlertController(title: "Please Email Me!", message: nil, preferredStyle: .alert)
let okAlert = UIAlertAction(title: "Ok!", style: .default)
failedMenu.addAction(okAlert)
presentingViewController.present(failedMenu, animated: true, completion: nil)
}
func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true)
}
}
现在，mailComposer可以从另一个UIViewController类中按如下方式打开。
let feedbackManager = FeedbackManager()
feedbackManager.sendEmail(presentingViewController: self)
希望对你有帮助