UIPageViewController的使用
1. 创建属性
创建一个UIPageViewController对象
@property (nonatomic, strong)UIPageViewController *pageVC;
创建一个数组用来存放要在pageViewController中展示的所有的控制器
@property (nonatomic, copy)NSArray *dataSource;
注: 如果你想在顶部加上几个按钮用以控制页面的跳转, 就需要创建以下两个属性
创建一个currentIndex作为当前是第几页的标识
@property (nonatomic, assign)NSInteger currentIndex;
定义一个静态变量temp_index来存放当前的是第几页的标识, 这个和上面的currentIndex属性不一样, temp_index是用来给currentIndex赋值的, 类似于一个侦察兵, 只有当temp_index确定控制器发生变化, 才会将temp_index的值赋给currentIndex
static NSInteger temp_index;
2.懒加载
- (NSArray *)dataSource {
if (!_dataSource) {
_dataSource = [NSArray arrayWithObjects:[LucyViewController new],[LucyViewController new],[LucyViewController new], nil];
}
return _dataSource;
}
这里我放了三个LucyViewController(其实就是ContentViewController), 仅仅用来展示
- (UIPageViewController *)pageVC {
if(!_pageVC) {
NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithInteger:10] forKey:UIPageViewControllerOptionInterPageSpacingKey];
_pageVC = [[UIPageViewController alloc]initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:options];
_pageVC.view.frame = CGRectMake(0, 64, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height - 64);
_pageVC.delegate=self;
_pageVC.dataSource=self;
//因为UIPageViewController也是继承自UIViewController, 所以采用addChildViewController方法
[self addChildViewController:_pageVC];
[self.view addSubview:_pageVC.view];
}
return _pageVC;
}
其中需要注意的是这个方法
_pageVC = [[UIPageViewController alloc]initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:options];
这个方法有三个参数:
1.style
这个参数是UIPageViewController翻页的过渡样式,系统提供了两种过度样式,分别是
UIPageViewControllerTransitionStylePageCurl : 卷曲样式类似翻书效果
UIPageViewControllerTransitionStyleScroll : UIScrollView滚动效果
2.navigationOrientation
这个参数是UIPageViewController导航方向,系统提供了两种方式,分别是
UIPageViewControllerNavigationOrientationHorizontal : 水平导航方式
UIPageViewControllerNavigationOrientationVertical : 垂直导航方式
3.options
这个参数是可选的,传入的是对UIPageViewController的一些配置组成的字典,不过这个参数只能以UIPageViewControllerOptionSpineLocationKey和UIPageViewControllerOptionInterPageSpacingKey这两个key组成的字典.
a). UIPageViewControllerOptionSpineLocationKey 这个key只有在style是翻书效果UIPageViewControllerTransitionStylePageCurl的时候才有作用, 它定义的是书脊的位置,值对应着UIPageViewControllerSpineLocation这个枚举项,不要定义错了哦.
b). UIPageViewControllerOptionInterPageSpacingKey这个key只有在style是UIScrollView滚动效果UIPageViewControllerTransitionStyleScroll的时候才有作用, 它定义的是两个页面之间的间距(默认间距是0).
3.初始化
- (void)viewDidLoad {
[super viewDidLoad];
//VCAtIndex是自定义的方法, 在后面
LucyViewController *lucyVC = [self VCAtIndex:0];
NSArray *vcs = [NSArray arrayWithObjects:lucyVC, nil];
[self.pageVC setViewControllers:vcs direction:UIPageViewControllerNavigationDirectionReverse animated:YES completion:nil];
}
4. 代理方法
UIPageViewControllerDataSource包含两个required的方法
//这个方法表示的是, 当前控制器的 前 一个控制器是什么, 我们要告诉pageVC
- (nullable UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController;
//这个方法表示的是, 当前控制器的 后 一个控制器是什么, 我们也要告诉pageVC
- (nullable UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController;
可做如下实现:
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
NSInteger index = [self indexOfVC:viewController];
if (index == 0 || index == NSNotFound) {
return nil;
}else {
index --;
return [self VCAtIndex:index];
}
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
NSInteger index = [self indexOfVC:viewController];
if (index == self.dataSource.count - 1 || index == NSNotFound) {
return nil;
}else {
index ++;
return [self VCAtIndex:index];
}
}
5.两个简单的工具方法
//通过当前的viewController得知当前的index
- (NSInteger)indexOfVC:(UIViewController *)vc {
return [self.dataSource indexOfObject:vc];
}
//通过当前的index得知当前的viewController
- (UIViewController *)VCAtIndex:(NSInteger)index {
return self.dataSource[index];
}
6.如果你不打算通过在顶部的按钮来控制页面的滚动, 那就不需要实现下面两个UIPageViewControllerDelegate方法
/*
如何获取下一个控制器的索引, 在上面两个数据源方法里无法获取准确的索引, 而应该在下面这个方法里获取:
pendingViewControllers里包含的就是 即将 显示的那个控制器, 是一个数组, 如果是单页显示的话, 其中只有一个元素
*/
- (void)pageViewController:(UIPageViewController *)pageViewController willTransitionToViewControllers:(NSArray<UIViewController *> *)pendingViewControllers {
UIViewController *firstVc = pendingViewControllers.firstObject;
NSInteger index = [self.dataSource indexOfObject:firstVc];
temp_index = index;
}
/*
这里是确定跳转到下一个vc了
*/
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray<UIViewController *> *)previousViewControllers transitionCompleted:(BOOL)completed {
if (completed) {
//已经跳转完成
self.currentIndex = temp_index;
}
}
顶部的三个按钮对应的拖进来的方法
- (IBAction)clickFirstButton:(UIButton *)sender {
self.currentIndex = 0;
[self.pageVC setViewControllers:@[self.dataSource[0]] direction:UIPageViewControllerNavigationDirectionReverse animated:YES completion:nil];
}
- (IBAction)clickSecondButton:(UIButton *)sender {
if (self.currentIndex > 1) {
[self.pageVC setViewControllers:@[self.dataSource[1]] direction:UIPageViewControllerNavigationDirectionReverse animated:YES completion:nil];
}else {
[self.pageVC setViewControllers:@[self.dataSource[1]] direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:nil];
}
self.currentIndex = 1;
}
- (IBAction)clickThirdButton:(UIButton *)sender {
[self.pageVC setViewControllers:@[self.dataSource[2]] direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:nil];
self.currentIndex = 2;
}
