结果是，使用非零发送者调用 -selectAll: 会显示菜单.用 nil 调用它会导致它选择文本，但不显示菜单.

Turns out, calling -selectAll: with a non-nil sender displays the menu. Calling it with nil causes it to select the text, but not display the menu.

在我从 Apple 收到关于它的错误报告并建议我通过 nil 而不是 self 后，我尝试了这个.

I tried this after my bug report about it came back from Apple with the suggestion that I pass nil instead of self.

无需使用 UIMenuController 或其他选择 API.

No need to muck with UIMenuController or other selection APIs.