Swift メール送信画面が開いてすぐに閉じてしまう

開発環境　Xcode10.3 / Swift5/ iOS12.3

カスタムキーボード上で、ボタンタップ時の座標を取得し、配列に格納し、CSVに変換してメールで送信するコードを以下のように実装しました。しかし、送信ボタンを押してもメール画面が現れてすぐに閉じてしまいます。
その際、以下のようにログにエラーが出ていますが、調べても対処法がわかりません。
１ヶ月ほど前に同様の方法で実装した時はちゃんと送信できていたのですが。。。
解決策をご教授いただけないでしょうか。よろしくお願いします。

Swift
1import UIKit
2import MessageUI
3
4class KeyboardViewController: UIInputViewController,MFMailComposeViewControllerDelegate {
5    
6    @IBOutlet var nextKeyboardButton: UIButton!
7    
8    let button1 = UIButton()
9    let button2 = UIButton()
10    var csvData = [[String]]()
11    let label = UILabel()
12    
13    override func updateViewConstraints() {
14        super.updateViewConstraints()
15        
16        // Add custom view sizing constraints here
17    }
18    
19    
20    // キーボードのサイズを変更するコード
21    override func viewWillAppear(_ animated: Bool) {
22        super.viewDidAppear(animated)
23        
24        //constantで高さ変更
25        let heightConstraint = NSLayoutConstraint(item: view, attribute: NSLayoutConstraint.Attribute.height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 500)
26        
27        self.view.addConstraint(heightConstraint)
28        
29    }
30    
31    
32    override func viewDidLoad() {
33        super.viewDidLoad()
34        
35        // Perform custom UI setup here
36        self.nextKeyboardButton = UIButton(type: .system)
37        self.nextKeyboardButton.setTitle(NSLocalizedString("Next Keyboard", comment: "Title for 'Next Keyboard' button"), for: [])
38        self.nextKeyboardButton.sizeToFit()
39        self.nextKeyboardButton.translatesAutoresizingMaskIntoConstraints = false
40        self.nextKeyboardButton.addTarget(self, action: #selector(handleInputModeList(from:with:)), for: .allTouchEvents)
41        self.view.addSubview(self.nextKeyboardButton)
42        
43        self.nextKeyboardButton.leftAnchor.constraint(equalTo: self.view.leftAnchor).isActive = true
44        self.nextKeyboardButton.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
45        
46        
47        // ボタンの設置座標とサイズを設定する.
48        button1.frame = CGRect(x: 100, y: 0, width: 200, height: 100)
49        button1.backgroundColor = UIColor.cyan
50        button1.setTitle("ボタン", for: .normal)
51        button1.addTarget(self, action: #selector(KeyboardViewController.onMyButton(_:forEvent:)), for: .touchDown)
52        view.addSubview(button1)
53        
54        // ボタンの設置座標とサイズを設定する.
55        button2.frame = CGRect(x: 100, y: 130, width: 200, height: 100)
56        button2.backgroundColor = UIColor.cyan
57        button2.setTitle("送信", for: .normal)
58        button2.addTarget(self, action: #selector(KeyboardViewController.onMyButton2(_:forEvent:)), for: .touchDown)
59        view.addSubview(button2)
60        
61        csvData = ([["x座標","y座標"]])
62        
63    }
64    
65    @objc func onMyButton(_ sender: UIButton, forEvent event: UIEvent) {
66        
67        let locationX = event.touches(for: sender)!.first!.location(in: view).x
68        let locationY = event.touches(for: sender)!.first!.location(in: view).y
69        
70        
71        print(Float(locationX),Float(locationY))
72        csvData.append([String(Float(locationX)),String(Float(locationY))])
73        
74        print(csvData)
75        
76    }
77    
78    //CSVへの変換
79    func toCSV(input: [[String]]) -> String {
80        return input.map {
81            $0.map {
82                $0.contains(",") || $0.contains("\"")
83                    ? "\"" + $0.replacingOccurrences(of: "\"", with: "\"\"") + "\""
84                    : $0
85                }.joined(separator: ",")
86            }.joined(separator: "\r\n")
87    }
88    
89    
90    @objc func onMyButton2(_ sender: UIButton, forEvent event: UIEvent) {
91        
92        //メールを送信できるかチェック
93        if MFMailComposeViewController.canSendMail()==false {
94            print("Email Send Failed")
95            return
96        }
97        sendMailWithCSV("実験データ", message: "", csv1: csvData)
98        
99    }
100    
101    
102    //メールでCSVを送信する
103    func sendMailWithCSV(_ subject: String, message: String, csv1: [[String]]) {
104        
105        let mailViewController = MFMailComposeViewController()
106        mailViewController.mailComposeDelegate = self
107        let toRecipients = ["******@gmail.com"] //送信先アドレスの入力
108        
109        mailViewController.setSubject(subject)
110        mailViewController.setToRecipients(toRecipients)
111        mailViewController.setMessageBody(message, isHTML: false)
112        //csvを添付、ファイル名の指定
113        mailViewController.addAttachmentData(toCSV(input: csv1).data(using: String.Encoding.shiftJIS, allowLossyConversion: false)!,mimeType: "csv", fileName: "keyboardTapData.csv")
114        
115        
116        self.present(mailViewController, animated: true) {}
117    }
118    
119    //メールの送信確認
120    func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
121        switch result {
122        case .cancelled:
123            print("キャンセル")
124        case .saved:
125            print("下書き保存")
126        case .sent:
127            print("送信成功")
128        default:
129            print("送信失敗")
130        }
131        dismiss(animated: true, completion: nil)
132    }
133    
134    
135    
136    
137    override func viewWillLayoutSubviews() {
138        self.nextKeyboardButton.isHidden = !self.needsInputModeSwitchKey
139        super.viewWillLayoutSubviews()
140    }
141    
142    override func textWillChange(_ textInput: UITextInput?) {
143        // The app is about to change the document's contents. Perform any preparation here.
144    }
145    
146    override func textDidChange(_ textInput: UITextInput?) {
147        // The app has just changed the document's contents, the document context has been updated.
148        
149        var textColor: UIColor
150        let proxy = self.textDocumentProxy
151        if proxy.keyboardAppearance == UIKeyboardAppearance.dark {
152            textColor = UIColor.white
153        } else {
154            textColor = UIColor.black
155        }
156        self.nextKeyboardButton.setTitleColor(textColor, for: [])
157    }
158    
159}
160

2019-08-10 23:10:05.488301+0900 timer kakunin[1937:23395] [General] #CompositionServices _serviceViewControllerReady: NSError Domain=NSCocoaErrorDomain Code=4099
キャンセル