Programming iOS 6, 3rd Edition

UITextView

A text view is sort of a scrollable, multiline version of a text field (UITextField, with which it should not be confused). It is a scroll view subclass (UIScrollView, Chapter 20), and thus has (by default) no border; it is not a control. Nevertheless, it has many close similarities to a text field. It has text, font, textColor, and textAlignment properties; it can be editable or not, according to its editable property. (You might use a scrollable noneditable text view instead of a UILabel, so as not to be limited to a fixed number of lines of text in a given height.) As with a text field, iOS 6 brings to a text view the attributedText, allowsEditingTextAttributes, and typingAttributes properties, as well as clearsOnInsertion. An editable text view governs its keyboard just as a text field does: when it is first responder, it is being edited and shows the keyboard, and it implements the UITextInput protocol and has inputView and inputAccessoryView properties. Its menu works the same way as a text field’s as well.

A thing to watch out for when replacing a UITextView’s attributedText is that aspects of its previous attributedText may contaminate the new attributed string. For example:

NSAttributedString* s1 =
    [[NSAttributedString alloc] initWithString:@"Hello there!"
     attributes:@{NSForegroundColorAttributeName:[UIColor redColor]}];
NSAttributedString* s2 = [[NSAttributedString alloc] initWithString:@"Howdy"];
self.tv.attributedText = s1;
self.tv.attributedText = s2;

The result ...