由于层次结构问题，无法显示由 MFMailComposeViewController 创建的页面 - Swift 4

Question

我尝试添加一个功能，即在用户触摸 table 中的一行后会弹出一个邮件页面。也就是说，这意味着用户可以在点击该行时激活 "function"（此处该函数的名称为 "orderOfSendAnEmailToReportTheProblem"）。我的所有代码如下所示。（这种代码已经被Whosebug上的几个genii提出了...）

import Foundation
import UIKit
import MessageUI

class ReportProblem : UIViewController, MFMailComposeViewControllerDelegate {

func orderOfSendAnEmailToReportTheProblem() {
    let mailComposeViewController = configureMailController()
    if MFMailComposeViewController.canSendMail() {
    self.present(mailComposeViewController, animated: true, completion: nil)
    } else {
        showMailError()
    }
}
//Activate the series of the commands of sending the email.


func configureMailController() -> MFMailComposeViewController {
    let mailComposeVC = MFMailComposeViewController()
    mailComposeVC.mailComposeDelegate = self

    mailComposeVC.setToRecipients(["my email"])
    mailComposeVC.setSubject("Yo")

    return mailComposeVC
}
//Set the recipient and the title of this email automatically.

func showMailError() {
    let sendMailErrorAlert = UIAlertController(title: "Could not sned the email.", message: "Oops, something was wrong, please check your internet connection once again.", preferredStyle: .alert)
    let dismiss = UIAlertAction(title: "Ok", style: .default, handler: nil)
    sendMailErrorAlert.addAction(dismiss)
    self.present(sendMailErrorAlert, animated: true, completion: nil) //If you conform the protocol of NSObject instead of UIViewController, you could not finish this line successfully.
}
//Set a alert window so that it would remind the user when the device could not send the email successfully.

func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
    controller.dismiss(animated: true, completion: nil)
}
//Set this final step so that the device would go to the previous window when you finish sending the email.
}

但是，出现了问题。当我在我的真实设备上测试它时，在我点击那个特定的行之后，没有任何反应，没有弹出任何新页面...... Xcode 只显示 "Warning: Attempt to present on whose view is not in the window hierarchy!" 我已经尝试了几种方法，例如作为 "view.bringSubview(toFront: mailComposeVC)" 或在我的代码末尾添加下面显示的代码，但没有任何效果。

func topMostController() -> UIViewController {
    var topController: UIViewController = UIApplication.shared.keyWindow!.rootViewController!
    while (topController.presentedViewController != nil) {
        topController = topController.presentedViewController!
    }
    return topController
}

我注意到有些人在创建alert时也会遇到类似的问题window，解决方法是创建一个独立的UIWindow，但我想用mailComposeController来呈现电子邮件页面。其他一些人也面临一些关于 MFMailComposeViewController 的问题，但他们的问题与层次结构无关。我是swift的新手，被这个问题困扰了一整天。。。我用swift4开发了我的App，有大神知道怎么解决这个问题么。。。 .

Answer 1

所以现在我正在编写另一种方式来呈现我用于通用视图的方式。在另一个 class 中有一些代码用于呈现视图，以便您可以使用这两种方法在整个应用程序中重复使用它们。

func slideInFromRight(parentView:UIView,childView:UIView) {
    childView.transform = CGAffineTransform(translationX: parentView.frame.maxX, y: 0)
    parentView.addSubview(childView)
    UIView.animate(withDuration: 0.25, animations: {
        childView.transform = CGAffineTransform(translationX: 0, y: 0)
    })
}

func slideOutToRight(view:UIView) {
    UIView.animate(withDuration: 0.25, animations: {
        view.transform = CGAffineTransform(translationX: view.frame.maxX, y: 0)
    },completion:{(completed:Bool) in
        view.removeFromSuperview()
    })
}

现在使用这些方法来呈现和移除自定义视图控制器，如下所示

let window = UIApplication.shared.keyWindow
let vc = YourViewController().instantiate()
self.addChildViewController(vc)
let view = vc.view

view.frame = CGRect(x: 0, y: 20, width: window!.frame.width, height: window!.frame.height-20)
//Here Animation is my custom presenter class and shared is it's shared instance.

Animation.shared.slideInFromRight(parentView: window!, childView: view)

//Or you can use current View controller's view 
Animation.shared.slideInFromRight(parentView: self.view!, childView: view)

Answer 2

天才 Vivek Singh，你的方法看起来不错，但有点乏味。而且，它在我的项目中仍然没有工作......（似乎你使用了一些关于UIView的代码，例如parentView，childView和view。但是，我使用了MFMailComposeViewController 好像和原来的看法有点不一样...不知道这个理论对不对...)

不过，我找到了解决办法。我推测问题是当用户点击另一个tableViewController中的行后（这里是SettingTVController），它会激活"another " [=27=中的函数“orderOfSendAnEmailToReportTheProblem( )” ]（这里是ReportProblem）。因为有两个不同的viewController，所以发生了某种冲突。

因此，我将我在上述问题中发布的所有代码移动到我原来的tableViewController，这样用户在激活功能时就不会进入另一个viewController，并且不再存在层次结构问题。

import UIKit
import StoreKit
import MessageUI

class SettingTVController: UITableViewController, MFMailComposeViewControllerDelegate {

var settingTitleConnection = showData()

override func viewDidLoad() {
    //skip
}

override func didReceiveMemoryWarning() {
   //skip
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
   //skip
}

override func numberOfSections(in tableView: UITableView) -> Int {
    //skip
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
   //skip
}



override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

    if tableView.indexPathForSelectedRow?.row == 2 && tableView.indexPathForSelectedRow?.section == 1 {
        orderOfSendAnEmailToReportTheProblem()
    } else {
      //skip
    }

    tableView.deselectRow(at: indexPath, animated: true)
}

//-----<The codes below is used to construct the function of reporting problem with email>-----
func orderOfSendAnEmailToReportTheProblem() {
    let mailComposeViewController = configureMailController()
    self.present(mailComposeViewController, animated: true, completion: nil)
    if MFMailComposeViewController.canSendMail() {
        self.present(mailComposeViewController, animated: false, completion: nil)
    } else {
        showMailError()
    }
}
//Activate the series of the commands of sending the email.

func configureMailController() -> MFMailComposeViewController {
    let mailComposeVC = MFMailComposeViewController()
    mailComposeVC.mailComposeDelegate = self

    mailComposeVC.setToRecipients(["datototest@icloud.com"])
    mailComposeVC.setSubject("Reporting of Problems of Rolling")

    return mailComposeVC
}
//Set the recipient and the title of this email automatically.

func showMailError() {
    let sendMailErrorAlert = UIAlertController(title: "Could not send the email.", message: "Oops, something was wrong, please check your internet connection once again.", preferredStyle: .alert)
    let dismiss = UIAlertAction(title: "Ok", style: .default, handler: nil)
    sendMailErrorAlert.addAction(dismiss)
    self.present(sendMailErrorAlert, animated: true, completion: nil) //If you conform the protocol of NSObject instead of UIViewController, you could not finish this line successfully.
}
//Set a alert window so that it would remind the user when the device could not send the email successfully.

func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
    controller.dismiss(animated: true, completion: nil)
    //UIApplication.shared.keyWindow?.rootViewController?.dismiss(animated: true, completion: nil)
}
//Set this final step so that the device would go to the previous window when you finish sending the email.
//-----<The codes above is used to construct the function of reporting problem with email>-----
}

我把我的代码贴在上面，希望有一天能帮助其他遇到类似问题的人。再次感谢您的帮助！！

Answer 3

我不知道您为什么会遇到视图层次结构问题。但我能够在 swift 4 中实现邮件共享选项。我遵循完全相同的步骤。

检查是否可以发送邮件：

MFMailComposeViewController.canSendMail()

配置邮件正文：

private func configureMailController() -> MFMailComposeViewController {
let mailComposeViewController = MFMailComposeViewController()
mailComposeViewController.mailComposeDelegate = self
mailComposeViewController.setMessageBody("MESSAGE BODY", isHTML: true)
return mailComposeViewController

}

当前邮件VC:

present(mailComposeViewController, animated: true)

确认可选协议并明确取消视图：

func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
controller.dismiss(animated: true)

}

由于层次结构问题，无法显示由 MFMailComposeViewController 创建的页面 - Swift 4

Page created by MFMailComposeViewController could not be shown because of hierarchy - Swift 4

hierarchy

uitableview

ios

swift

mfmailcomposeviewcontroller