Smoky: UITextView, UITextViewDelegate, UITextInputTraits

On my iPod Touch (640 × 1136),

A UITextView is like the UITextField we saw here, except that a UITextView can hold many lines of text. It can also scroll up and down because it is derived from class UIScrollView. I put a ViewController on top of the UITextView, and a UITabBarController on top of the ViewController, because everyone expects the UITextView to be displayed under a navigation bar containing an Edit/Done button.

The ViewController contains the edit method called when the user presses the Edit button, which calls becomeFirstResponder to display the keyboard. The ViewController also acts as the UITextView’s delegate, containing the methods that are called when the user finishes editing. These methods are textViewShouldEndEditing(_:) and textViewDidEndEditing(_:), and are triggered by the Edit/Done button.

The Supporting Files folder contains the text file undedited.txt. When the app is first launched, the loadView method of the ViewController displays this file in the UITextView. Each time editing ends, the textViewDidEndEditing(_:) method of the ViewController writes the edited text into a file named edited.txt.

To confirm that the write to the file was successful, the ViewController modally displays an orange view with some statistics. I put a plain vanilla UIViewController on top of the orange view, and a UINavigationController on top of the plain vanilla UIViewController, because everyone expects the orange view to be displayed under a navigation bar containing an OK button.

To restore the file to its original state, uninstall and re-install the app. On Top of Old Smoky: Wikipedia article, Weavers’ recording.

Source code in

  1. Class AppDelegate pushes the ViewController onto the UINavigationController.
  2. Class ViewController has a navigationBar that contains a button that alternates between Edit and Done.

Run the app

If the keyboard does not appear when you press the Edit button when running on the iOS Simulator,
Hardware → Keyboard → Toggle Software Keyboard

If you’re running on the iOS Simulator, you can search for edited.txt in the finder, or in with

find / -name edited.txt 2> /dev/null

cat /Users/mark/Library/Developer/CoreSimulator/Devices/01EBED35-F21B-4B4C-95BC-BFDDDC6264B4/data/Containers/Data/Application/A9A9FAD9-960A-444F-B970-52DE97195D54/Documents/edited.txt

Write the string into a file

The textViewDidEndEditing(_:). method of class ViewController writes the text of the UITextView into a file named exited.txt. I had to use NSUTF8StringEncoding because NSASCIIStringEncoding gave me the error message “The operation couldn’t be completed. (Cocoa error 517.)” when the text contained emoji characters such as this \u1F601 😁

Things to try

  1. Accept the user’s text and write it to a file only if the text is non-empty.
    	func textViewShouldEndEditing(textView: UITextView) -> Bool {
    		if textView.text == "" {
    			return false;	//Keep the keyboard visible.
    		} else {
    			return true;	//Hide the keyboard and call textViewDidEndEditing(_:).
    which can be abbreviated to
    	func textViewShouldEndEditing(textView: UITextView) -> Bool {
    		return textView.text != "";
    or to
    	func textViewShouldEndEditing(textView: UITextView) -> Bool {
    		return !textView.text.isEmpty;