ScrollView: PageControl点不随页面变化

Question

我写了一个带有TableView和detailView的iPhone应用程序，其中包含一个包含2个页面(都包含一个图像)的ScrollView和一个显示2个白点的pageControl。

它似乎工作得很完美。视图向左滚动并显示下一页(就像它应该显示的那样)，除了scrollView下的小白点(PageControl点)。如果我按下小圆点:页面滚动，第二个圆点突出显示(完美！)。但是如果我滑动第一页(用拇指手动)到下一页，白点不会随之改变。(它应该突出显示第二个点)。

希望有人能帮我。我已经将代码读了10遍，并搜索了我能找到的所有示例代码。

下面是我的代码：

#import <UIKit/UIKit.h>

@interface DetailViewController : UIViewController

<UIScrollViewDelegate>
    {

 NSString *selectedImage1;
 NSString *selectedImage2;
 NSNumber *selectedNpages;

 IBOutlet UIScrollView* scrollView;
 IBOutlet UIPageControl* pageControl;

 BOOL pageControlIsChangingPage;
    }

@property (nonatomic, retain) NSString *selectedImage1;    
@property (nonatomic, retain) NSString *selectedImage2;    
@property (nonatomic, retain) NSNumber *selectedNpages;    
@property (nonatomic, retain) UIView *scrollView;    
@property (nonatomic, retain) UIPageControl* pageControl;

-(IBAction)changePage:(id)sender;    
-(void)setupPage;

 @end



#import "DetailViewController.h"

@implementation DetailViewController


@synthesize selectedImage1;
@synthesize selectedImage2;
@synthesize selectedNpages;
@synthesize scrollView;
@synthesize pageControl;


#pragma mark -
#pragma mark UIView boilerplate
- (void)viewDidLoad 
{
 [self setupPage];
 [super viewDidLoad];
}


- (void)didReceiveMemoryWarning 
{
    [super didReceiveMemoryWarning];
}

- (void)viewDidUnload 
{ 
 [scrollView release];
 [pageControl release];
}



#pragma mark -
#pragma mark The Guts
- (void)setupPage
{

 scrollView.scrollsToTop = NO;
 scrollView.delegate = self; 
 scrollView.indicatorStyle = UIScrollViewIndicatorStyleWhite;
 scrollView.clipsToBounds = YES;
 scrollView.scrollEnabled = YES;
 scrollView.pagingEnabled = YES;
 scrollView.showsHorizontalScrollIndicator = NO;
 scrollView.showsVerticalScrollIndicator = NO;
 [scrollView setCanCancelContentTouches:NO];
 pageControl.currentPage = 0;

 NSString *image1a = selectedImage1;
 NSString *image2a = selectedImage2;

 CGFloat cx = 0;


 //FIRST PAGE

  // Image

 UIImage *bimage = [UIImage imageWithContentsOfFile: [[NSBundle mainBundle]  pathForResource:image1a ofType:@"jpg"]];
 UIImageView *bimageView = [[UIImageView alloc] initWithImage:bimage];

 CGRect brect = bimageView.frame;

 brect.size.height = bimage.size.height;
 brect.size.width = bimage.size.width;
 brect.origin.x = ((scrollView.frame.size.width - bimage.size.width) / 2) + cx;
 brect.origin.y = ((scrollView.frame.size.height - bimage.size.height) / 2);

 bimageView.frame = brect; 
 [scrollView addSubview:bimageView];

 [bimageView release];

 cx += scrollView.frame.size.width;


 //SECOND PAGE

 if([selectedNpages intValue] == 2)
 {

  //Image

  UIImage *bimage2 = [UIImage imageWithContentsOfFile: [[NSBundle mainBundle]    pathForResource:image2a ofType:@"jpg"]];
  UIImageView *bimage2View = [[UIImageView alloc] initWithImage:bimage2];

  UIImageView *bimageView2 = [[UIImageView alloc] initWithImage:bimage2];

  CGRect brect2 = bimageView2.frame;
  brect2.size.height = bimage2.size.height;
  brect2.size.width = bimage2.size.width;
  brect2.origin.x = ((scrollView.frame.size.width - bimage2.size.width) / 2) + cx;
  brect2.origin.y = ((scrollView.frame.size.height - bimage2.size.height) / 2);

  bimageView2.frame = brect2;

  [scrollView addSubview:bimageView2];
  [bimageView2 release];

  cx += scrollView.frame.size.width;

 }

 self.pageControl.numberOfPages = [selectedNpages intValue];

 [scrollView setContentSize:CGSizeMake(cx, [scrollView bounds].size.height)]; 

 [image1a release];
 [image2a release]; 
}

#pragma mark -
#pragma mark UIScrollViewDelegate stuff

- (void)ScrollViewDidScroll:(UIScrollView *)_scrollView
{
    if (pageControlIsChangingPage) {
        return;
    }
 CGFloat pageWidth = _scrollView.frame.size.width;
 int page = floor((_scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;

 pageControl.currentPage = page;
}


- (void)ScrollViewDidEndDecelerating:(UIScrollView *)_scrollView 
{
    pageControlIsChangingPage = NO;
}

#pragma mark -
#pragma mark PageControl stuff
- (IBAction)changePage:(id)sender 
{
    CGRect frame = scrollView.frame;
    frame.origin.x = frame.size.width * pageControl.currentPage;
    frame.origin.y = 0;

    [scrollView scrollRectToVisible:frame animated:YES]; 

    pageControlIsChangingPage = YES;
}


- (void)dealloc {
 [DetailViewController release];
 [selectedImage1 release];
 [selectedImage2 release];
 [selectedImage2 release];
 [selectedNpages release];
 [super dealloc];
}

@end

感谢您抽出时间阅读这篇文章。

Answer 1

ScrollViewDidScroll:应该以小写的"S“开头，就像这样的scrollViewDidScroll:。这同样适用于scrollViewDidEndDecelerating:。

在Objective-C中，你应该总是以小写字符开始方法。大写是为类名，常量，也许是全局变量保留的。方法-从不！

Answer 2

如果Michal的答案不能解决这个问题，试试这个：

接口生成器中的pageControl IBOutlet是否已连接到您的类？如果未连接，- (void)scrollViewDidScroll:(UIScrollView *)_scrollView中的pageControl.currentPage = page;不会更改选定的点。