用iPhone中的页面控制刷图像(第2部分)

我正在尝试制作练习应用程序，可以在其中滚动图像使用页面控制。我能够滚动图像，并能够包含页面控件。但是我遇到的问题是我无法将两者互联。意思是说我滚动图像时，页面控件不会受到影响，并且当我更改页面控件时，图像的滚动不受影响。

我指的是此网站：http：//www.raywenderlich.com/10518/how-to-to-use-uscrollview-to-scroll-scroll-and-zoom-content

viewController.h

#import <UIKit/UIKit.h>
@interface ViewController : UIViewController <UIScrollViewDelegate>
@property (nonatomic, strong) IBOutlet UIScrollView *scrollView;
@property (nonatomic, strong) IBOutlet UIPageControl *pageControl;
@property (nonatomic, strong) NSArray *pageImages;
@property (nonatomic, strong) NSMutableArray *pageViews;
- (void)loadVisiblePages;
- (void)loadPage:(NSInteger)page;
- (void)purgePage:(NSInteger)page;
@end

viewcontroller.m

#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
@synthesize scrollView = _scrollView;
@synthesize pageControl = _pageControl;
@synthesize pageImages = _pageImages;
@synthesize pageViews = _pageViews;
- (void)loadPage:(NSInteger)page {
    if (page < 0 || page >= self.pageImages.count) {
        // If it's outside the range of what you have to display, then do nothing
        return;
    }
    // 1
    UIView *pageView = [self.pageViews objectAtIndex:page];
    if ((NSNull*)pageView == [NSNull null]) {
        // 2
        CGRect frame = self.scrollView.bounds;
        frame.origin.x = frame.size.width * page;
        frame.origin.y = 0.0f;
        // 3
        UIImageView *newPageView = [[UIImageView alloc] initWithImage:[self.pageImages objectAtIndex:page]];
        newPageView.contentMode = UIViewContentModeScaleAspectFit;
        newPageView.frame = frame;
        [self.scrollView addSubview:newPageView];
        // 4
        [self.pageViews replaceObjectAtIndex:page withObject:newPageView];
    }
}
- (void)loadVisiblePages {
    // First, determine which page is currently visible
    CGFloat pageWidth = self.scrollView.frame.size.width;
    NSInteger page = (NSInteger)floor((self.scrollView.contentOffset.x * 2.0f + pageWidth) / (pageWidth * 2.0f));
    // Update the page control
    self.pageControl.currentPage = page;
    // Work out which pages you want to load
    NSInteger firstPage = page - 1;
    NSInteger lastPage = page + 1;
    // Purge anything before the first page
    for (NSInteger i=0; i<firstPage; i++) {
        [self purgePage:i];
    }
    // Load pages in our range
    for (NSInteger i=firstPage; i<=lastPage; i++) {
        [self loadPage:i];
    }
    // Purge anything after the last page
    for (NSInteger i=lastPage+1; i<self.pageImages.count; i++) {
        [self purgePage:i];
    }
}
- (void)purgePage:(NSInteger)page {
    if (page < 0 || page >= self.pageImages.count) {
        // If it's outside the range of what you have to display, then do nothing
        return;
    }
    // Remove a page from the scroll view and reset the container array
    UIView *pageView = [self.pageViews objectAtIndex:page];
    if ((NSNull*)pageView != [NSNull null]) {
        [pageView removeFromSuperview];
        [self.pageViews replaceObjectAtIndex:page withObject:[NSNull null]];
    }
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    // Load the pages that are now on screen
    [self loadVisiblePages];
}
- (void)viewDidLoad
{
    [super viewDidLoad];
    // 1
    self.pageImages = [[NSArray alloc] initWithObjects:
                       [UIImage imageNamed:@"1.jpeg"],
                       [UIImage imageNamed:@"2.jpeg"],
                       [UIImage imageNamed:@"3.jpeg"],
                       nil];
    NSInteger pageCount = self.pageImages.count;
    // 2
    self.pageControl.currentPage = 0;
    self.pageControl.numberOfPages = pageCount;
    // 3
    self.pageViews = [[NSMutableArray alloc] init];
    for (NSInteger i = 0; i < pageCount; ++i) {
        [self.pageViews addObject:[NSNull null]];
    }
}
- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    // 4
    CGSize pagesScrollViewSize = self.scrollView.frame.size;
    self.scrollView.contentSize = CGSizeMake(pagesScrollViewSize.width * self.pageImages.count, pagesScrollViewSize.height);
    // 5
    [self loadVisiblePages];
}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
@end

第三张图像没有出现，仍然无法链接pagecontrol和图像的滚动。需要一些指导...

NSInteger page = (NSInteger)floor((self.scrollView.contentOffset.x * 2.0f + pageWidth) / (pageWidth * 2.0f));

NSInteger page = self.scrollView.contentOffset.x / self.scrollView.frame.size.width;