问题
Using UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification, string); to announce things with VoiceOver. This works great for summaries etc.
The problem is in announcing entered/deleted text, VoiceOver uses a deeper tone when echoing the text you enter, and deeper still when you delete text. The documentation mentions no way to control the tone of Voice, is there some unicode character you can put in the string or any argument you can pass to do this?
来源：https://stackoverflow.com/questions/12578873/voiceover-uiaccessibilityannouncementnotification-tone-of-voice