iOS自带手写键盘奔溃问题

很多时候为了满足需求，我们需要在UIScrollView添加UITextField，在处理键盘升降键盘事件的时候往往会写个UIScrollView的分类，代码

- (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];
}

后来我们的测试发现一个问题，当使用iOS自带手写键盘的时候输入第一个字变灰，再点击点击奔溃了。

调试了很久，我发现手写键盘在调用UIScrollView的这个分类的方法时，self的类型是UIKBCandidateCollectionView，具体是什么还没有去苹果官方文档查，先屏蔽了，代码

- (void)touchesBegan:(NSSet<UITouch *> *)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];
        }
    }
}

解决