Question

我有CollectionView设置，显示来自服务器的远程图像数据。我可以在CollectionView中查看图片，但在点按DetailView的项目时没有显示任何内容。当我使用本地图像时它工作正常，但在添加＆＃34; SDWebImage框架＆＃34; 后，当我点击DetailView时，我无法查看图像。我认为问题在于prepareForSegue方法，但我尝试过的任何方法都无法解决问题。我在＆＃34; StackOverflow＆＃34;上搜索过很多问题，但无法找到这个特定问题的答案。

以下是CollectionViewController的代码：

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *identifier = @"Cell";

    CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

    [cell.thumbnailView setImageWithURL:[NSURL URLWithString:[photos objectAtIndex:indexPath.row]] placeholderImage:[UIImage imageNamed:@"logo.png"] options:SDWebImageRefreshCached];

    return cell;

}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"displayDetail"]) {
        PhotoViewController *destViewController = (PhotoViewController *)segue.destinationViewController;
        NSIndexPath *indexPath = [self.collectionView indexPathForCell:sender];
        NSString *imagePath = [photos objectAtIndex:indexPath.row];
        UIImage *image = [UIImage imageNamed:imagePath];
        NSLog(@"Image named: %@ at row %ld", imagePath, (long)indexPath.row);
        destViewController.largeImage = image;
    }
}

segue触发正常，但在点击后只在PhotoViewController.m显示白屏。

Answer 1

从我在代码中看到的内容，您使用setImageWithURL类的SDWebImage方法构建了thumbnailView。

然后，当您构建大型视图时，将图像的网址传递给[UIImage imageNamed:imagePath]。

从SDWebImage的文档中，我看到它是UIImageView的扩展。因此，您只需在您的segue准备中致电[destViewController.imageView setImageWithURL:...]。

您的prepareForSegue应该是这样的：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"displayDetail"]) {
        PhotoViewController *destViewController = (PhotoViewController *)segue.destinationViewController;
        NSIndexPath *indexPath = [self.collectionView indexPathForCell:sender];
        NSString *imagePath = [photos objectAtIndex:indexPath.row];
        NSLog(@"Image named: %@ at row %ld", imagePath, (long)indexPath.row);

        [destViewController.imageView
                     setImageWithURL:[NSURL URLWithString:imagePath]
                    placeholderImage:[UIImage imageNamed:@"logo.png"] 
                             options:SDWebImageRefreshCached];
    }
}

修改

在PhotoViewController的viewDidLoad中，您不必对此做任何事情。只需确保在实施#import <SDWebImage/UIImageView+WebCache.h>的文件中导入prepareForSegue。

Answer 2

我最终重新修改了我显示数据的方式，并设法使其工作。

这是我使用的代码：

<强> CollectionViewController.h

#import <UIKit/UIKit.h>
#import "PhotoViewController.h"
#import "CollectionViewCell.h"

@class PhotoViewController;

@interface CollectionViewController : UICollectionViewController <UICollectionViewDataSource, UICollectionViewDelegate>

@property (nonatomic, strong) PhotoViewController *photoViewController;

@end

<强> CollectionViewController.m

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([[segue identifier] isEqualToString:@"displayDetail"]) {
    PhotoViewController *destViewController = segue.destinationViewController;
    NSIndexPath *indexPath = [[self.collectionView indexPathsForSelectedItems] lastObject];
    NSString *largeImageURL = [photos objectAtIndex:indexPath.row];
    destViewController.imageURL = [NSURL URLWithString:largeImageURL];
    }
}

<强> PhotoViewController.h

#import <UIKit/UIKit.h>
#import "CollectionViewController.h"

@interface PhotoViewController : UIViewController

@property (strong, nonatomic) IBOutlet UIImageView *imageView;
@property (strong, nonatomic) NSURL *imageURL;

@end

<强> PhotoViewController.m

#import "PhotoViewController.h"
#import <SDWebImage/UIImageView+WebCache.h>
#import "UIImageView+WebCache.h"

@interface PhotoViewController ()

@end

@implementation PhotoViewController

@synthesize imageURL = _imageURL;
@synthesize imageView = _imageView;

#pragma mark - Managing the detail item

- (void)setImageURL:(NSURL *)imageURL
{
    if (_imageURL != imageURL)
    {
        _imageURL = imageURL;
        [self configureView];
    }
}

- (void)configureView
{
    if (self.imageURL)
        // NSLog(@"%@", self.imageURL);
    {
        // NSLog(@"%@", self.imageView);
        [self.imageView setImageWithURL:self.imageURL placeholderImage:nil options:SDWebImageProgressiveDownload progress:^(NSInteger receivedSize, NSInteger expectedSize)
         {
         }
             completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType)
         {
             // NSLog(@"%@", image);
         }];
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self configureView];

}

CollectionView prepareForSegue不将图像数据发送到DetailView

2 个答案: