Question

我编写了一个带有TableView和detailView的iPhone应用程序，其中包含一个包含2页（包含图像）的ScrollView和一个显示2个白点的pageControl。

它似乎完美无缺。视图向左滚动并显示下一页（就像它应该的那样）除了scrollView下的小白点（PageControl点）。如果我按下小点：页面滚动，第二个点突出显示（完美！）。但如果我将第一页（用我的拇指手工制作）滑到下一页，白点就不会随之改变。（它应突出显示第二个点）。

希望有人可以帮助我。我已经阅读了10次代码并搜索了我可以找到的示例代码。

这是我的代码：

#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

感谢您花时间阅读本文。

Answer 1

ScrollViewDidScroll:应以小写“S”开头，例如scrollViewDidScroll:。这同样适用于scrollViewDidEndDecelerating:。

好吧，在Objective-C中，您应该始终使用小写字符启动方法。大写保留用于类名，常量，也可以是全局变量。方法 - 从不！

Answer 2

如果Michal的答案没有解决，请尝试：

在Interface Builder中将pageControl IBOutlet连接到您的班级？如果未连接，则pageControl.currentPage = page;中的- (void)scrollViewDidScroll:(UIScrollView *)_scrollView不会更改所选的点。

ScrollView：PageControl点不随页面而变化

2 个答案: