1、問題描述：通過手寫鍵盤操作的時候，鍵盤下面會出現(xiàn)灰色的條塊，然后點擊屏幕的任何位置應用直接崩潰。
2、問題截圖：

崩潰截圖.jpg

3、問題分析：
有一個用scrollview做的一個編號輸入頁面，只要在填寫時，切換到手寫輸入法，手寫之后就會crash，然后錯誤提示：[UIKBBlurredKeyView candidateList]: unrecognized selector sent to instance，之前從來沒遇到過這種錯誤，一直不知所措。
由于之前開發(fā)的時候，為了讓填寫表單是彈出的鍵盤能點擊空白處收回鍵盤，就給scrollview寫了一個分類，重寫了三個方法。

• (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
  [[self nextResponder] touchesBegan:touches withEvent:event];
  [super touchesBegan:touches withEvent:event];
  }

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    [[self nextResponder] touchesBegan:touches withEvent:event];
    [super touchesBegan:touches withEvent:event];
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    [[self nextResponder] touchesMoved:touches withEvent:event];
    [super touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    [[self nextResponder] touchesEnded:touches withEvent:event];
    [super touchesEnded:touches withEvent:event];
}

手寫輸入法和這個分類處理手勢沖突導致app crash了。調試了很久，我發(fā)現(xiàn)手寫鍵盤在調用UIScrollView的這個分類的方法時，self的類型是UIKBCandidateCollectionView，一種系統(tǒng)沒有暴露出來的類型，應該是UIScrollView的一個子類，所以解決辦法就呼之欲出了，直接上代碼。

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    if (![self isMemberOfClass:[UIScrollView class]]) {

    } else {
        [[self nextResponder] touchesBegan:touches withEvent:event];
        if ([super respondsToSelector:@selector(touchesBegan:withEvent:)]) {
            [super touchesBegan:touches withEvent:event];
        }
    }
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    if (![self isMemberOfClass:[UIScrollView class]]) {

    } else {
        [[self nextResponder] touchesMoved:touches withEvent:event];
        if ([super respondsToSelector:@selector(touchesBegan:withEvent:)]) {
            [super touchesMoved:touches withEvent:event];
        }
    }
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    if (![self isMemberOfClass:[UIScrollView class]]) {

    } else {
        [[self nextResponder] touchesEnded:touches withEvent:event];
        if ([super respondsToSelector:@selector(touchesBegan:withEvent:)]) {
            [super touchesEnded:touches withEvent:event];
        }
    }
}