Question

最近我编写了关于UIPageViewController的这个小教程： http://www.appcoda.com/uipageviewcontroller-tutorial-intro/

在本教程之后，我想知道是否可以将页面指示器的位置更改为屏幕顶部。

有谁知道怎么做？

修改

感谢您的帮助。我关注这篇文章： How to put the UIPageControl element on top of the sliding pages within a UIPageViewController?

现在我将页面控件置于顶部，但发生了一些奇怪的事情：如果从第1页滑动到第2页，则指示符表示用户在第3页上。我输入了一个NSLog，它显示当前索引，当它从0到1而不是2时滑到下一页时它会发生变化。

有人知道为什么吗？

当前代码：

@property (weak, nonatomic) IBOutlet UIPageControl *pageControl;

@end

@implementation APPViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    self.pageController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];

    self.pageController.dataSource = self;
    [[self.pageController view] setFrame:[[self view] bounds]];

    APPChildViewController *initialViewController = [self viewControllerAtIndex:0];

    NSArray *viewControllers = [NSArray arrayWithObject:initialViewController];

    [self.pageController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];

    [self addChildViewController:self.pageController];
    [[self view] addSubview:[self.pageController view]];
    [self.pageController didMoveToParentViewController:self];
    UIPageControl *pageControl = [UIPageControl appearance];
    pageControl.pageIndicatorTintColor = [UIColor lightGrayColor];
    pageControl.currentPageIndicatorTintColor = [UIColor orangeColor];
    [self.view bringSubviewToFront:self.pageControl];


    //Or whatever number of viewcontrollers you have
    [self.pageControl setNumberOfPages:5];

    }

- (APPChildViewController *)viewControllerAtIndex:(NSUInteger)index {

    APPChildViewController *childViewController = [[APPChildViewController alloc] initWithNibName:@"APPChildViewController" bundle:nil];
    childViewController.index = index;

    return childViewController;

}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {

    NSUInteger index = [(APPChildViewController *)viewController index];

    if (index == 0) {
        return nil;
    }

    // Decrease the index by 1 to return
    index--;
    [self.pageControl setCurrentPage:index];

    return [self viewControllerAtIndex:index];

}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {

    NSUInteger index = [(APPChildViewController *)viewController index];

    index++;
    [self.pageControl setCurrentPage:index];

    if (index == 5) {
        return nil;
    }

    return [self viewControllerAtIndex:index];

}

AppChildViewController：

@property (assign, nonatomic) NSInteger index;    
- (void)viewDidLoad {

        [super viewDidLoad];
        // Do any additional setup after loading the view from its nib.
        switch(self.index)
        {
            case zero: {
                self.imageView.image = [UIImage imageNamed:@"page1.png"];
                NSLog(@"%d",self.index);
                break;
            }
            case one: {
                self.imageView.image = [UIImage imageNamed:@"page2.png"];
                NSLog(@"%d",self.index);
                break;
            }
            case two: {
                self.imageView.image = [UIImage imageNamed:@"page3.png"];
                NSLog(@"%d",self.index);
                break;
            }
            case three: {
                self.imageView.image = [UIImage imageNamed:@"page4.png"];
                NSLog(@"%d",self.index);
                break;
            }
            default: {
                self.imageView.image = [UIImage imageNamed:@"page5.png"];
                NSLog(@"%d",self.index);
                break;
            }
        }
    }

Answer 1

在我们的应用程序中，我将页面指示器放在页面视图控制器视图的顶部，方法是将视图翻转过来。这真的很傻，除非你有信心，否则我不建议使用这种技术。它是这样的：

[pageWrapperView setTransform:CGAffineTransformRotate([pagingView transform], M_PI)];

页面视图控制器的视图是pageWrapperView的子视图。

然后你也需要翻转内容视图，所以它们是正确的方式。

我有a demo on Github where this technique is used to put a tab bar at the top of the screen。

Answer 2

您是否尝试过显式创建页面控件并使用给定的框架添加视图，例如：

UIPageControl *pageControl = [UIPageControl alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 44)];
[self.view addSubView:pageControl];

...或类似的东西？

Answer 3

您无法在viewControllerAfterViewController和viewControllerBeforeViewController中处理页面索引，因为在页面更改时不会被调用，并且您将无法获得正确的索引。

相反，我建议你在pageViewController: didFinishAnimating:previousViewControllers:transitionCompleted:

处理它

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed {
    if (finished) {
        APPChildViewController *childViewController = [pageViewController.viewControllers firstObject];
        [self.pageControl setCurrentPage:childViewController.index];
    }
}

UIPageViewController页面指示器位置

3 个答案: