Question

在xcode中怎么添加uipagecontrol

Answer 1

虽然看上去用 UIPageControl 在一系列 UIView或UIViewController中导航是很平常的事情,但实际上 Apple公司并没有提供一个这样的方法或者演示Demo:
在最新的iOS版本中(5.0 现在已经不是最新的),Apple公司提供了很多如何用其他方式实现
UIViewController容器的方式(可以从这里参考),但悲剧的是它们与 UIPageControl 没多大关系.
那么我们今天就来专门解决这个问题.
创建界面
首先我们需要在 Interface Builder 中在一个UIViewController里面创建一个UIPageControl与UIScrollView.当然你可以创建很多类似的UIViewController.
设置 PageViewController 类
这里的 PageViewController 对象将包含一个 UIScrollView 与一个 UIPageControl.而且 UIScrollView 将会包含所有的 subview,这些subview就是被UIPageControl控制的子页面.
你也许会在 viewController 中添加一些算法来专门处理页面转换:addChildViewController:方法.然而在我这个案例中却不是这么做的,来一起看看代码：
@interface PagerViewController :UIViewController
@property (nonatomic,strong) IBOutlet UIScrollView *scrollView;
@property (nonatomic,strong) IBOutlet UIPageControl *pageControl;
- (IBAction)changePage:(id)sender;
@end
在实现的代码文件中,首先我先不让它能够旋转屏幕.然后当 PagerViewController 预备显示时,我们需要标记一下当前哪一个view是被激活的,即被显示的,那么需要在 viewDidApplear 以及 viewWillDisappear方法中加入以下代码：
- (BOOL)automaticallyForwardAppearanceAndRotationMethodsToChildViewControllers {
return NO;
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
UIViewController *viewController = [self.childViewControllers objectAtIndex:self.pageControl.currentPage];
if (viewController.view.superview != nil) {
[viewController viewDidAppear:animated];
}
}
- (void)viewWillDisappear:(BOOL)animated {
UIViewController *viewController = [self.childViewControllers objectAtIndex:self.pageControl.currentPage];
if (viewController.view.superview != nil) {
[viewController viewWillDisappear:animated];
}
[super viewWillDisappear:animated];
}
- (void)viewDidDisappear:(BOOL)animated {
UIViewController *viewController = [self.childViewControllers objectAtIndex:self.pageControl.currentPage];
if (viewController.view.superview != nil) {
[viewController viewDidDisappear:animated];
}
[super viewDidDisappear:animated];
}
viewWillAppear 可能会有点复杂,因为我们也需要加载所有的子view到 scrollView中,而且必须确保scrollview的contentsize比子view要大.
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
for (NSUInteger i =0; i < [self.childViewControllers count]; i++) {
[self loadScrollViewWithPage:i];
}
self.pageControl.currentPage = 0;
_page = 0;
[self.pageControl setNumberOfPages:[self.childViewControllers count]];
UIViewController *viewController = [self.childViewControllers objectAtIndex:self.pageControl.currentPage];
if (viewController.view.superview != nil) {
[viewController viewWillAppear:animated];
}
self.scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * [self.childViewControllers count],scrollView.frame.size.height);
}
为了将UIViewController的内容加载到UIScrolView的contentView中,需要如下代码:
- (void)loadScrollViewWithPage:(int)page {
if (page < 0)
return;
if (page >= [self.childViewControllers count])
return;
// replace the placeholder if necessary
UIViewController *controller = [self.childViewControllers objectAtIndex:page];
if (controller == nil) {
return;
}
// add the controller's view to the scroll view
if (controller.view.superview == nil) {
CGRect frame = self.scrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
controller.view.frame = frame;
[self.scrollView addSubview:controller.view];
}
}