如何设置在 NSTextStorage 中输入的 *next* 字符的属性

Question

It's simple enough to change the text attributes in a given range of NSTextStorage .

storage.addAttribute(.font, value: UIFont.systemFont(ofSize: 30), at: range)

But how do I change the attributes at the current cursor position so that the next character has different attributes?

(Think someone clicking the "bold" button in a toolbar with no text selected. No text turns bold, but the next character is bold.)

Answer 1

You can use UITextView.typingAttributes to achieve this.

This dictionary contains the attribute keys (and corresponding values) to apply to newly typed text. When the text view's selection changes, the contents of the dictionary are cleared automatically.

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    // This is the key part
    textView.typingAttributes = myCurrentAttributes

    // Allow system to control typing
    return true
}