MFMailComposeViewController未检测到UITouchEvents

Question

我有一个简单的MFMailComposeViewController，它出现在我现有的视图控制器上，我试图通过检测UITouches来检查用户是否正在对此进行任何活动，但我无法记录在视图控制器上的任何UITouches，我尝试添加另一个具有清晰颜色的视图，但这只是禁用我的邮件编辑器上的交互，请建议。

ViewController代码

import Foundation
import UIKit
import MessageUI

class ViewController: UIViewController , MFMailComposeViewControllerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        let mailComposeViewController = configuredMailComposeViewController()
        if MFMailComposeViewController.canSendMail() {
            self.presentViewController(mailComposeViewController, animated: true, completion: nil)
        } else {
            self.showSendMailErrorAlert()
        }

        let bounds = UIScreen.mainScreen().bounds
        let width = bounds.size.width
        let height = bounds.size.height

        let rect = CGRect(x: 0, y: 0, width: width, height: height);
        let testLayer = CustomView(frame: rect)
        testLayer.backgroundColor = UIColor.clearColor()
        mailComposeViewController.view.addSubview(testLayer)

    }

    @IBAction func sendEmailButtonTapped(sender: AnyObject) {
        let mailComposeViewController = configuredMailComposeViewController()
        if MFMailComposeViewController.canSendMail() {
            self.presentViewController(mailComposeViewController, animated: true, completion: nil)
        } else {
            self.showSendMailErrorAlert()
        }
    }

    func configuredMailComposeViewController() -> MFMailComposeViewController {
        let mailComposerVC = MFMailComposeViewController()
        mailComposerVC.mailComposeDelegate = self // Extremely important to set the --mailComposeDelegate-- property, NOT the --delegate-- property

        mailComposerVC.setToRecipients(["someone@somewhere.com"])
        mailComposerVC.setSubject("Sending you an in-app e-mail...")
        mailComposerVC.setMessageBody("Sending e-mail in-app is not so bad!", isHTML: false)

        return mailComposerVC
    }

    func showSendMailErrorAlert() {
        let sendMailErrorAlert = UIAlertView(title: "Could Not Send Email", message: "Your device could not send e-mail.  Please check e-mail configuration and try again.", delegate: self, cancelButtonTitle: "OK")
        sendMailErrorAlert.show()
    }

    // MARK: MFMailComposeViewControllerDelegate Method
    func mailComposeController(controller: MFMailComposeViewController!, didFinishWithResult result: MFMailComposeResult, error: NSError!) {
        controller.dismissViewControllerAnimated(true, completion: nil)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        print("inside mail composer view")
    }
}

CustomView的代码

import UIKit

class CustomView: UIView {


    // Only override drawRect: if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func drawRect(rect: CGRect) {
        // Drawing code

    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        print("touches started")
    }

}