我正在寻找一种可靠的方式来跟踪 UIPageViewController 当前索引。
这个问题众所周知;尽管 viewControllers 被正确呈现,但很难跟踪当前索引。
我认为在 SO 社区刷新这个话题会很好,因为它由于某种原因仍未解决
我在这里浏览了很多主题,但大多数答案都已过时或标记为不可靠(结果取决于用户是完全滑动还是只滑动一半等)
我访问过this线程,但它没有提供任何明确的正确答案。
我试过:
1) 跟踪 viewController 的 View 标签 - link - 总是返回 0
2) 查看 UIPageViewController 方法 viewControllerBeforeViewController
和 viewControllerAfterViewControlle
中的索引变量
它的结果是不可预测的,有时它会跳过一个索引等。
有没有人想出一个好的、可靠的方法来跟踪 UIPageCiewController 索引并使用它(例如打印当前索引)?
我很欣赏 obj-c 和 swift 实现,但 swift 是我正在寻找的。p>
最佳答案
这是针对 ObjC
ParentViewController
#import "PagesViewController.h"
// Delegate: PageViewDelegate
// Declared inside `PagesViewController`
//
@interface ParentViewController () <UIPageViewControllerDataSource, UIPageViewControllerDelegate, PageViewDelegate>
@property (nonatomic) UIPageViewController *pageViewController;
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];
self.pageViewController.dataSource = self;
self.pageViewController.view.frame = self.view.frame;
// im setting page 3 as the default page
//
[self.pageViewController setViewControllers:[NSArray arrayWithObject:[self viewControllerAtIndex:3]] direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:nil];
[self addChildViewController:self.pageViewController];
[self.view addSubview:self.pageViewController.view];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
NSUInteger index = [(PagesViewController *)viewController index];
if (index == 0) {
return nil;
}
index--;
return [self viewControllerAtIndex:index];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
NSUInteger index = [(PagesViewController *)viewController index];
index++;
if (index == 5) {
return nil;
}
return [self viewControllerAtIndex:index];
}
- (PagesViewController *)viewControllerAtIndex:(NSInteger)index
{
PagesViewController *vc = [[PagesViewController alloc] init];
// set delegate here..
//
vc.delegate = self;
// other data
//
vc.index = index;
vc.titleLabel = [NSString stringWithFormat:@"Screen :%ld", (long)index];
return vc;
}
- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController
{ // The number of items reflected in the page indicator. return x; }
- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController
{ // The selected item reflected in the page indicator. return x; }
// This is what you need
//
- (void)viewController:(id)VC didShowWithIndex:(long)index
{
NSLog(@"didShowWithIndex: %ld", index);
}
PagesViewController.h
@protocol PageViewDelegate <NSObject>
- (void)viewController:(id)VC didShowWithIndex:(long)index;
@end
@interface PagesViewController : UIViewController
@property (weak) id <PageViewDelegate> delegate;
@property (nonatomic) NSInteger index;
@property (nonatomic) NSString *titleLabel;
@end
PagesViewController.m
@implementation PagesViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.view.backgroundColor = [UIColor blackColor];
UILabel *titleLabel = [[UILabel alloc] initWithFrame:self.view.frame];
titleLabel.textAlignment = NSTextAlignmentCenter;
titleLabel.textColor = [UIColor whiteColor];
titleLabel.text = self.titleLabel;
[self.view addSubview:titleLabel];
}
// Trigger delegate here
//
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[self.delegate viewController:self didShowWithIndex:self.index];
}
@end
关于ios - 获取 UIPageViewController 当前索引的可靠方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/36857455/