ios - 页面 View Controller 数据源

关闭。这个问题需要details or clarity .它目前不接受答案。

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Best Answer-推荐答案

基本上你有一个 UIPageViewController。它当前在所有 N 个页面中的索引 K 处显示一个页面。 UIPageViewController 需要知道正在显示的当前页面之前的页面(在索引 K 处)和当前页面之后的页面。

看起来是这样的:

//Called on the data source. Returns the UIViewController before the 
//current one (viewController) within the UIPageViewController (pageViewController)
- (UIViewController *)pageViewControllerUIPageViewController *)pageViewController viewControllerBeforeViewControllerUIViewController *)viewController
{
    //gets the index of the page currently showing
    NSUInteger index = ((PageContentViewController*) viewController).pageIndex;

    //Checks that it's not the first page and that it's
    //actually a part of the UIPageViewController
    if ((index == 0) || (index == NSNotFound)) {
        //If it is, then there is no page before it.
        return nil;
    }

    //otherwise, lets go back one index
    index--;
    //and then this is the UIViewController before it
    return [self viewControllerAtIndex:index];
}

对于第二种方法，它做同样的事情，但试图获取之后的页面。同样，iOS 需要了解这些信息，以便在用户更改页面时快速呈现该页面。

- (UIViewController *)pageViewControllerUIPageViewController *)pageViewController viewControllerAfterViewControllerUIViewController *)viewController
{
    //gets the index of the current page being shown
    NSUInteger index = ((PageContentViewController*) viewController).pageIndex;

    //if it's not found, then there isn't a page after it
    if (index == NSNotFound) {
        return nil;
    }

    //go to the next index
    index++;
    //if we're at the end of the pages
    if (index == [self.pageTitles count]) {
        //there's no page after it
        return nil;
    }
    //otherwise, return the next UIViewController
    return [self viewControllerAtIndex:index];
}

关于ios - 页面 View Controller 数据源，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/33087447/