Question

对于我正在处理的应用程序，我需要一个带有分页的scrollview以及一些视图（在本例中为tableviews）。设置它（使用Apple的PageControl示例）非常简单，我可以毫不费力地使它在页面之间滚动和捕捉。我希望tableviews几乎像scrollview中tableviews的缩略图表示。一旦你点击一个它打开或放大，让tableview覆盖整个屏幕。再次，设置它并不是一个真正的问题，我可以在scrollview中创建我想要的任何大小的视图，并且当我到达那个部分时点击我确定我可以开始工作。 :)

我的问题是：在任何给定的视图中，无论您碰巧在哪个页面，我都希望下一页和上一页分别在右侧和左侧略微可见。当然，在第一页上，只有一页显示在右侧，或左侧显示在最后一页。同样，通过设置显示的视图（tableviews）的x-origin，我可以让第一页看起来正确。但是，一旦滚动问题就会变得明显，即屏幕滚动得太远。

打破它我猜我的主要问题是我似乎无法改变切换页面时完成的滚动量。

我很感激我能得到的任何帮助，谢谢。

AppDelegate.h

#import <UIKit/UIKit.h>

@interface AppDelegate : NSObject <UIApplicationDelegate, UIScrollViewDelegate> {
UIWindow *window;
UIView *background;
UIScrollView *scrollView;
UIPageControl *pageControl;
NSMutableArray *viewControllers;

// To be used when scrolls originate from the UIPageControl
// I've commented this out (and all references to it) since I've disabled user interaction with the UIPageControl
//BOOL pageControlUsed;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet UIView *background;

@property (nonatomic, retain) IBOutlet UIScrollView *scrollView;
@property (nonatomic, retain) IBOutlet UIPageControl *pageControl;
@property (nonatomic, retain) NSMutableArray *viewControllers;

- (IBAction)changePage:(id)sender;

@end

AppDelegate.m

#import "AppDelegate.h"
#import "MyViewController.h"

static NSUInteger kNumberOfPages = 4;

@interface AppDelegate (PrivateMethods)

- (void)loadScrollViewWithPage:(int)page;
- (void)scrollViewDidScroll:(UIScrollView *)sender;

@end

@implementation AppDelegate

@synthesize window, scrollView, pageControl, viewControllers, background;

- (void)dealloc {
[background release];
[viewControllers release];
[scrollView release];
[pageControl release];
[window release];
[super dealloc];
}

- (void)applicationDidFinishLaunching:(UIApplication *)application {

background.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"Background.png"]];

// view controllers are created lazily
// in the meantime, load the array with placeholders which will be replaced on demand
NSMutableArray *controllers = [[NSMutableArray alloc] init];
for (unsigned i = 0; i < kNumberOfPages; i++) {
    [controllers addObject:[NSNull null]];
}
self.viewControllers = controllers;
[controllers release];

// a page is the width of the scroll view
scrollView.pagingEnabled = YES;
scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * kNumberOfPages, scrollView.frame.size.height);
scrollView.showsHorizontalScrollIndicator = NO;
scrollView.showsVerticalScrollIndicator = NO;
scrollView.scrollsToTop = NO;
scrollView.delegate = self;

pageControl.numberOfPages = kNumberOfPages;
pageControl.currentPage = 0;

// pages are created on demand
// load the visible page
// load the page on either side to avoid flashes when the user starts scrolling
[self loadScrollViewWithPage:0];
[self loadScrollViewWithPage:1];
}

- (void)loadScrollViewWithPage:(int)page {
if (page < 0) return;
if (page >= kNumberOfPages) return;

// replace the placeholder if necessary
MyViewController *controller = [viewControllers objectAtIndex:page];
if ((NSNull *)controller == [NSNull null]) {
    controller = [[MyViewController alloc] initWithPageNumber:page];
    [viewControllers replaceObjectAtIndex:page withObject:controller];
    [controller release];
}

// add the controller's view to the scroll view
if (nil == controller.view.superview) {
    CGRect frame = CGRectMake(50, 50, 220, 330);
    frame.origin.x = 50 + (250 * page);
    frame.origin.y = 50;
    controller.view.frame = frame;
    [scrollView addSubview:controller.view];
}
}

- (void)scrollViewDidScroll:(UIScrollView *)sender {
// We don't want a "feedback loop" between the UIPageControl and the scroll delegate in
// which a scroll event generated from the user hitting the page control triggers updates from
// the delegate method. We use a boolean to disable the delegate logic when the page control is used.
/*if (pageControlUsed) {
    // do nothing - the scroll was initiated from the page control, not the user dragging
    return;
}*/

// Switch the indicator when more than 50% of the previous/next page is visible
CGFloat pageWidth = scrollView.frame.size.width;
int page = floor((scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
pageControl.currentPage = page;

// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling)
[self loadScrollViewWithPage:page - 1];
[self loadScrollViewWithPage:page];
[self loadScrollViewWithPage:page + 1];

// A possible optimization would be to unload the views+controllers which are no longer visible
}

// At the begin of scroll dragging, reset the boolean used when scrolls originate from the UIPageControl
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
//pageControlUsed = NO;
}

// At the end of scroll animation, reset the boolean used when scrolls originate from the UIPageControl
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
//pageControlUsed = NO;
}

- (IBAction)changePage:(id)sender {
int page = pageControl.currentPage;

// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling)
[self loadScrollViewWithPage:page - 1];
[self loadScrollViewWithPage:page];
[self loadScrollViewWithPage:page + 1];

// update the scroll view to the appropriate page
CGRect frame = scrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
[scrollView scrollRectToVisible:frame animated:YES];

// Set the boolean used when scrolls originate from the UIPageControl. See       scrollViewDidScroll: above.
//pageControlUsed = YES;
}

@end

Answer 1

您似乎正在设置scrollView的帧大小和controller.view的帧不同。 scrollView是一个IBOutlet，这意味着您正在创建scrollView以使用界面构建器，但是您使用以下行来放置内容：

CGRect frame = CGRectMake(50, 50, 220, 330);
frame.origin.x = 50 + (250 * page);
frame.origin.y = 50;
controller.view.frame = frame;
[scrollView addSubview:controller.view];

并将其放入scrollView。如果您不想看到scrollView侧面的上一页/下一页，则必须更改第一行使用的数字。尝试使用`scrollView.frame.size或检查你从IB创建的scrollView的帧大小，并使用它们而不是魔术数字，你应该避免。

使用UIScrollView和PageControl定义滚动量

1 个答案: