iphone - 放大 UIscrollview 使图像子视图消失

Question

我的主要动机是创建一个类似于 iPad 图片库的屏幕。图片来自服务器，可以是 5 或 50 或 100 等数字。我按照 Ray Wenderlich 的教程一步一步完成了它（http://www.raywenderlich.com/10518/how-to-use-uiscrollview -to-scroll-and-zoom-content）但仍然面临问题。
我有一个主滚动视图（外部），我想在其中拥有这些图像，这样我就可以使用滚动（和分页）功能放大/缩小每个图像，并且当我双击图像时它应该放大到 2 倍和第二次加倍它应该恢复正常。
为此，我有一个内部滚动视图，它将为每个图像保存一个 UIImageview。这样每张图片都可以放大/缩小。但是当我加载图像时，我只能看到第一张图像，其他图像没有显示。当我设置每个滚动视图和图像视图的背景颜色时，我也知道问题出在它们身上，但我不知道它是什么：

我的代码中的问题在哪里，我在互联网上搜索了很多但无法弄清楚，并且我尝试了许多其他示例。

下面是我的代码

.h 文件

    #import <UIKit/UIKit.h>


@interface SliderViewController : UIViewController<UIScrollViewDelegate,MFMailComposeViewControllerDelegate,UIPrintInteractionControllerDelegate,UIAlertViewDelegate,UIPopoverControllerDelegate,ButtonPressedDelegate>
{

    NSMutableArray *thumbsArray;
    int index;
    int count;
    UIView *containerView;
    bool isEmpty;
    NSString *firstName;
    NSString *lastName;
    NSMutableArray *annotatedThumbsArray;
}


@property(nonatomic,retain) NSMutableArray *thumbsArray;
@property(nonatomic, assign) int index;
@property(nonatomic, assign) int count;
@property(nonatomic,retain) NSString *firstName;
@property(nonatomic,retain) NSString *lastName;
@property(nonatomic,retain) NSMutableArray *annotatedThumbsArray;
@property(nonatomic,retain) UIPopoverController *popover_controller;

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

@end

.m 文件：

#import "SliderViewController.h"

#import "AppDelegate.h"

#define VIEW_FOR_ZOOM_TAG (10)

@interface SliderViewController ()
{
    UITapGestureRecognizer *singleFingerTap;
    CGRect rect;
}
    @property (nonatomic, strong) NSMutableArray *pageImages;
    @property (nonatomic, strong) NSMutableArray *pageViews;
    
    - (void)loadVisiblePages;
    - (void)loadPage:(NSInteger)page;
    - (void)purgePage:(NSInteger)page;

@end

implementation SliderViewController
@synthesize pageImages,pageControl,libid,libname,thumbsArray,index,count,imageNameLabel,imageNameView,footerView,navBar,firstName,lastName,annotatedThumbsArray;
@synthesize drawingViewController,popover_controller;

@synthesize pageViews = _pageViews;
@synthesize scrollView = _scrollView;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}


#pragma mark - view cycle
- (void)viewDidLoad
{
    [super viewDidLoad];
    
    NSLog(@"THUMBSSSSS%@",thumbsArray);
    pageImages = [[NSMutableArray alloc]init];
    isEmpty = false;
    
    self.scrollView.backgroundColor = [UIColor greenColor];
    
    
    
    NSInteger pageCount = self.thumbsArray.count;
    
    // Set up the page control
    self.pageControl.currentPage = index;
    self.pageControl.numberOfPages = pageCount;
    
    // Set up the array to hold the views for each page
    _pageViews = [[NSMutableArray alloc] init];
    for (NSInteger i = 0; i < pageCount; ++i)
    {
        [_pageViews addObject:[NSNull null]];
    }
    
    self.navBar.topItem.title = [NSString stringWithFormat:@"%@ %@",self.firstName,self.lastName];
    
    singleFingerTap =
    [[UITapGestureRecognizer alloc] initWithTarget:self
                                            action:@selector(viewTapped:)];
    [self.view addGestureRecognizer:singleFingerTap];
    
    rect = CGRectZero;

}

- (void)centerScrollViewContents
{
    CGSize boundsSize = self.scrollView.bounds.size;
    CGRect contentsFrame = [self.scrollView viewWithTag:202].frame;
    
    if (contentsFrame.size.width < boundsSize.width) {
        contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2.0f;
    } else {
        contentsFrame.origin.x = 0.0f;
    }
    
    if (contentsFrame.size.height < boundsSize.height)
    {
        contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0f;
    }
    else
    {
        contentsFrame.origin.y = 0.0f;
    }
    
    [self.scrollView viewWithTag:202].frame = contentsFrame;
}


-(void)setViewContents
{
    // Set up the content size of the scroll view
    CGSize pagesScrollViewSize = self.scrollView.frame.size;
    self.scrollView.contentSize = CGSizeMake(pagesScrollViewSize.width * self.thumbsArray.count, pagesScrollViewSize.height);
    [self.scrollView setContentOffset:CGPointMake(index*pagesScrollViewSize.width, 0.0f)];
    self.scrollView.delegate = self;
    
    self.navBar.topItem.title = [NSString stringWithFormat:@"%@ %@",firstName,lastName];
    
    // Load the initial set of pages that are on screen
    [self loadVisiblePages];
    
    [self centerScrollViewContents];
}

-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    
    

    [self setViewContents];
    [self performSelectorOnMainThread:@selector(showHeaderFooterViews) withObject:nil waitUntilDone:YES];
}
- (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
        isEmpty = false;
        NSInteger firstPage = page - 1;
        NSInteger lastPage = page + 1;
        
        // Purge anything before the first page
        for (NSInteger i=0; i<firstPage; i++) {
            [self purgePage:i];
        }
        for (NSInteger i=firstPage; i<=lastPage; i++) {
            [self loadPage:i];
        }
        for (NSInteger i=lastPage+1; i<self.thumbsArray.count; i++) {
            [self purgePage:i];
        }
        
        thumbnail *tempThumb = [[thumbnail alloc]init];
        tempThumb = [thumbsArray objectAtIndex:page];
        NSString *image_name = [[NSString alloc]initWithFormat:@"%@",tempThumb.name];
        tempThumb = nil;
        [self.imageNameLabel setText:[NSString stringWithFormat:@"%@(%d/%d)",image_name,pageControl.currentPage+1,pageControl.numberOfPages]];
}


-(void)purgePage:(NSInteger)page
{
        if(page < 0 || page >= self.thumbsArray.count+self.annotatedThumbsArray.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 = [_pageViews objectAtIndex:page];
        if ((NSNull*)pageView != [NSNull null])
        {
            [pageView removeFromSuperview];
            [_pageViews replaceObjectAtIndex:page withObject:[NSNull null]];
        }
}

- (void)loadPage:(NSInteger)page
{
    @try
    {
        if (page < 0 || page >= self.thumbsArray.count)
        {
            // If it's outside the range of what we have to display, then do nothing
            return;
        }
        
        // Load an individual page, first checking if you've already loaded it
        UIView *pageView = [_pageViews objectAtIndex:page]; // page views holds
        
        
        if ((NSNull*)pageView == [NSNull null] || isEmpty)
        {
            CGRect frame = self.scrollView.bounds;
            frame.origin.x = frame.size.width * page;
            frame.origin.y = 0.0f;
            frame = CGRectInset(frame, 10.0f, 0.0f);
            
            thumbnail *tempThumb = [[thumbnail alloc]init];
            tempThumb = [thumbsArray objectAtIndex:page];
            NSString *image_name = [[NSString alloc]initWithFormat:@"%@",tempThumb.name];
            tempThumb = nil;
            
            NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
            NSString *documentDir = [path objectAtIndex:0];
            NSString *docsPath = [documentDir stringByAppendingPathComponent:[NSString stringWithFormat:@"downloaded/%@",libid]];
            UIImage *fullImage = [[UIImage alloc]init];
            NSString *imagePath;
            
            if(page<(thumbsArray.count-annotatedThumbsArray.count))
            {
                imagePath = [docsPath stringByAppendingPathComponent:image_name];
            }
            else
            {
                documentDir = [documentDir stringByAppendingPathComponent:libid];
                imagePath = [documentDir stringByAppendingPathComponent:image_name];
            }
            BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:imagePath];
            if(fileExists)
            {
                NSLog(@"file NAMEEEE: - %@",image_name);
                fullImage = [UIImage imageWithContentsOfFile:imagePath];
            }
            else
            {
                NSLog(@"FILE NOT FOUND");
                fullImage = [UIImage imageNamed:@"noimage.jpg"];
                isEmpty = true;
            }
            
            UIImageView *newPageView = [[UIImageView alloc] initWithImage:fullImage];
            [newPageView setUserInteractionEnabled:YES];
            newPageView.contentMode = UIViewContentModeScaleAspectFit;
            newPageView.frame = frame;
            newPageView.backgroundColor = [UIColor blueColor];
            newPageView.tag = VIEW_FOR_ZOOM_TAG;

            // ******* add each image view into a scroll view so that it can be zoomed and also can be swiped
            UIScrollView *pageScrollView = [[UIScrollView alloc] initWithFrame:frame];
            pageScrollView.tag = 202;
            pageScrollView.minimumZoomScale = 1.0f;
            pageScrollView.maximumZoomScale = 2.0f;
            pageScrollView.zoomScale = 1.0f;
//            pageScrollView.contentSize = newPageView.bounds.size;
            pageScrollView.delegate = self;
            pageScrollView.showsHorizontalScrollIndicator = NO;
            pageScrollView.showsVerticalScrollIndicator = NO;
            pageScrollView.backgroundColor = [UIColor yellowColor];

            [self.scrollView addSubview:pageScrollView];
            [pageScrollView addSubview:newPageView];
            [self.scrollView bringSubviewToFront:pageScrollView];

            NSLog(@"frame --> %f", frame.origin.x);
            NSLog(@"frame --> %f", newPageView.frame.origin.x);
            NSLog(@"frame --> %f", pageScrollView.frame.origin.x);
            
            [self.pageViews replaceObjectAtIndex:page withObject:newPageView];
            
            UITapGestureRecognizer *doubleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(viewDoubleTapped:)];
            doubleTapRecognizer.numberOfTapsRequired = 2;
            doubleTapRecognizer.numberOfTouchesRequired = 1;
            [newPageView addGestureRecognizer:doubleTapRecognizer];

        }

    }
    @catch (NSException *exception)
    {
        NSLog(@"crash in - loadPage = %@", exception);
    }
    @finally {
//        NSLog(@"finally-");
    }
}
#pragma mark - double tapped

-(void)viewDoubleTapped:(UITapGestureRecognizer*)recognizer
{
   //TODO: code for 2x zooming in / out 
}

#pragma mrak - view tapped
-(void) viewTapped:(UITapGestureRecognizer*)recognizer
{
    if([self.footerView isHidden])
    {
        [self performSelectorOnMainThread:@selector(showHeaderFooterViews) withObject:nil waitUntilDone:YES];
    }
}
- (void)showHeaderFooterViews
{
    [self.imageNameView setHidden:NO];
    [self.footerView setHidden:NO];

    [self performSelector:@selector(hideHeaderFooterViews) withObject:nil afterDelay:5.0];
    
}

- (void)hideHeaderFooterViews
{
    NSLog(@"hide header footer called ");
    [self.imageNameView setHidden:YES];
    [self.footerView setHidden:YES];
}



#pragma mark - back button (cross button ) pressed

- (IBAction)backButtonPressed:(id)sender
{
    @try
    {
        AppDelegate* myAppDelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
        
        int l = [[[myAppDelegate window].rootViewController childViewControllers] count];// to access the previous controller
        
        FolderViewController *parentVC = (FolderViewController *)((UITabBarController *)[[[myAppDelegate window].rootViewController childViewControllers] objectAtIndex:l-2]); // accessing FolderviewC
        [parentVC loadThumbnails];
        
        
        [self.view removeFromSuperview];
        [self removeFromParentViewController];
    }
    @catch (NSException *exception) {
        NSLog(@"crash in SliderVC: backButtonPressed - %@", exception);
    }
    @finally {
        
    }
}


#pragma  mark - scroll view delegate

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    // Load the pages that are now on screen
    [self loadVisiblePages];
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    if(scrollView.tag == 202)
        return [scrollView viewWithTag:VIEW_FOR_ZOOM_TAG];
    
    return nil;
}


- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    NSLog(@"view zoomed");
    [self centerScrollViewContents ];
}

- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view
{
    NSLog(@"Beginning zooming");
}

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale{
    NSLog(@"Zooming Did End");
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)swipeRight:(id)sender
{
    if (!((self.scrollView.contentOffset.x+self.scrollView.frame.size.width) >= self.scrollView.contentSize.width))
    {
        [self.scrollView setContentOffset:CGPointMake(self.scrollView.contentOffset.x+self.scrollView.frame.size.width, self.scrollView.contentOffset.y)];
        [self loadVisiblePages];
    }
}

- (IBAction)swipeLeft:(id)sender
{
    if (!((self.scrollView.contentOffset.x-self.scrollView.frame.size.width) < 0))
    {
        [self.scrollView setContentOffset:CGPointMake(self.scrollView.contentOffset.x-self.scrollView.frame.size.width, self.scrollView.contentOffset.y)];
        [self loadVisiblePages];
    }
}

注意：我已将我从服务器获取的图像保存在 Documents 目录中，并从我的loadPage:方法中访问它们（这是访问这些图像的正确位置吗？）

iphone - 放大 UIscrollview 使图像子视图消失

0 回答 0

Related

Reference