2020/12/28(Mon) 21:29:49 A Swift example of Custom Views for Data Input (custom in-app keyboard) - Stack Overflow https://stackoverflow.com/questions/33474771/a-swift-example-of-custom-views-for-data-input-custom-in-app-keyboard/57275689#57275689
上記サイトをメインに下記サイトで知識を補って、ボタンをタップすると定型文を入力するカスタムキーボードを自分専用に作ってみました。
意外と便利。
Apple の資料
2020/12/28(Mon) 21:45:20 App Extension Programming Guide： Custom Keyboard https://developer.apple.com/library/archive/documentation/General/Conceptual/ExtensibilityPG/CustomKeyboard.html#//apple_ref/doc/uid/TP40014214-CH16-SW1 2020/12/28(Mon) 20:27:47 Creating a Custom Keyboard | Apple Developer Documentation https://developer.apple.com/documentation/uikit/keyboards_and_input/creating_a_custom_keyboard 2020/12/28(Mon) 20:27:29 Handling Text Interactions in Custom Keyboards | Apple Developer Documentation https://developer.apple.com/documentation/uikit/keyboards_and_input/creating_a_custom_keyboard/handling_text_interactions_in_custom_keyboards 2020/12/28(Mon) 21:47:37 textDocumentProxy | Apple Developer Documentation https://developer.apple.com/documentation/uikit/uiinputviewcontroller/1618193-textdocumentproxy 2020/12/28(Mon) 21:48:02 UITextDocumentProxy | Apple Developer Documentation https://developer.apple.com/documentation/uikit/uitextdocumentproxy
その他
2020/12/28(Mon) 21:41:54 Creating a Custom Keyboard Using iOS 8 App Extension https://www.appcoda.com/custom-keyboard-tutorial/ 2020/12/28(Mon) 21:46:56 Custom Keyboard Extensions： Getting Started | raywenderlich.com https://www.raywenderlich.com/49-custom-keyboard-extensions-getting-started