错误的原因：
*** Terminating app due to uncaught exception 'UIViewControllerHierarchyInconsistency', reason: 'child view controller:<UICompatibilityInputViewController: 0x7fe168592d00> should have parent view controller:<WDKRichChatViewController: 0x7fe1686655b0> but requested parent is:<UIInputWindowController: 0x7fe168852a00>'
情景复现：
当我给cell添加长按手势的时候，要实现UIMenuController，但是蹦到了 [self becomeFirstResponder] 这一句，翻阅了各种百度，终于知道了原因：
Your view controller probably has a property named inputView that is merely a subview, not an inputView as UIResponder interface expects it to be. Starting with iOS 8 they check that UIResponder's inputView has no parent.
这是百度出来的，于是按照这个方向去找，发现我的控制器添加上了这句：
@property (nonatomic, strong) ChatInputPanel *inputView; 于是，注释了，便好了。
附上提供思路的链接地址：http://*.com/questions/26928849/error-when-try-becomefirstresponder-call-for-uimenucontroller