在哪种情况下iOS调用-accessibilityScroll：？

我在表视图中实现了所有辅助功能操作方法，并添加了"adjustable"特征 . 我使用UITableView进行自定义控制，通过滚动选择项目 . 它没有要选择的典型行 . 它用于滚动，标记显示所选内容 . 类似于UIPickerView或Weightbot中的选择器 . 选择活动日期是自定义的date picker control .

但iOS从不调用我的辅助功能操作方法 . 在表格视图中向上或向下轻拂Voice Over无法正常反应 . 它疯狂地跳来跳去 .

我必须为语音设置代理或数据源吗？当用户像UIPickerView一样向上/向下滑动时，如何才能正确地向上/向下移动我的表格视图？

了解Apple如何使用VoiceOver可以访问UIDatePicker将会有很大帮助 . 它为每列使用UITableView . 您可以在列之间拖动以选择列 . 然后你可以向上滑动增加或减少 .

EDIT ：以递归方式转发有关UIDatePicker的信息以查看其设置方式 .

UIDatePicker: 
     _UIDatePickerView: 
         UIView: 
         _UIOnePartImageView: 
         _UIPickerWheelView: 
         _UIPickerViewSelectionBar: 
         UIPickerTableView:; contentOffset: {0, 2.19991e+06}>
             UIPickerTableViewWrapperCell: 
                 UITableViewCellContentView: 
                 UIDatePickerWeekMonthDayView: 
                     UILabel: {label = 28. Jul} {traits = staticText } {accessibilityIncrement} {accessibilityDecrement} {accessibilityScroll:} {accessibilityPerformEscape} {accessibilityPerformMagicTap}

它在设置/实现时打印所有可用的可访问性相关内容 . 就像你可以看到的，奇怪的是表视图单元格的UILabel实现了scroll方法 . 这对我来说没有意义 . 为什么是这样？为什么不是UIPickerTableView本身？并且在整个UIDatePicker中也没有可调整的特性 .

这是我用来转储这些信息的代码 . 为了确定，我在2秒延迟后最初在UIDatePicker上调用它 . 我将此代码放在UIView上的类别中 .

- (NSString *)description {
    NSString *className = NSStringFromClass([self class]);

    NSMutableString *str = [NSMutableString stringWithFormat:@"%@: ", className];

    if (self.isAccessibilityElement) {
        if (self.accessibilityLabel) {
            [str appendFormat:@"{label = %@} ", self.accessibilityLabel];
        }

        UIAccessibilityTraits traits = self.accessibilityTraits;
        [str appendString:@"{traits = "];
        if (traits & UIAccessibilityTraitAdjustable) {
            [str appendString:@"adjustable "];
        }
        if (traits & UIAccessibilityTraitAllowsDirectInteraction) {
            [str appendString:@"interaction "];
        }
        if (traits & UIAccessibilityTraitButton) {
            [str appendString:@"button "];
        }
        if (traits & UIAccessibilityTraitCausesPageTurn) {
            [str appendString:@"pageTurn "];
        }
        if (traits & UIAccessibilityTraitHeader) {
            [str appendString:@"header "];
        }
        if (traits & UIAccessibilityTraitImage) {
            [str appendString:@"image "];
        }
        if (traits & UIAccessibilityTraitKeyboardKey) {
            [str appendString:@"kbKey "];
        }
        if (traits & UIAccessibilityTraitLink) {
            [str appendString:@"link "];
        }
        if (traits & UIAccessibilityTraitNone) {
            [str appendString:@"none "];
        }
        if (traits & UIAccessibilityTraitNotEnabled) {
            [str appendString:@"notEnabled "];
        }
        if (traits & UIAccessibilityTraitPlaysSound) {
            [str appendString:@"sound "];
        }
        if (traits & UIAccessibilityTraitSearchField) {
            [str appendString:@"search "];
        }
        if (traits & UIAccessibilityTraitSelected) {
            [str appendString:@"selected "];
        }
        if (traits & UIAccessibilityTraitStaticText) {
            [str appendString:@"staticText "];
        }
        if (traits & UIAccessibilityTraitSummaryElement) {
            [str appendString:@"summaryElement "];
        }
        if (traits & UIAccessibilityTraitUpdatesFrequently) {
            [str appendString:@"updatesFreq "];
        }
        [str appendString:@"} "];


        if ([self respondsToSelector:@selector(accessibilityIncrement)]) {
            [str appendString:@"{accessibilityIncrement} "];
        }
        if ([self respondsToSelector:@selector(accessibilityDecrement)]) {
            [str appendString:@"{accessibilityDecrement} "];
        }
        if ([self respondsToSelector:@selector(accessibilityScroll:)]) {
            [str appendString:@"{accessibilityScroll:} "];
        }
        if ([self respondsToSelector:@selector(accessibilityPerformEscape)]) {
            [str appendString:@"{accessibilityPerformEscape} "];
        }
        if ([self respondsToSelector:@selector(accessibilityPerformMagicTap)]) {
            [str appendString:@"{accessibilityPerformMagicTap} "];
        }
    }


    return str;
}