ios - UIImageView 不显示来自 UITableViewController 的设置图像

Question

我有一个 UITableViewController带有图像名称列表。单击名称时，图像的 URL 设置在 ImageViewController 中。然后是 UITableViewController转至 ImageViewController包含 UIImageView (与 socket 相连)。在 ImageViewController的viewDidLoad我设置了UIImageView从 URL 到图像，但是当我在模拟器上运行它时，只有一个黑屏出现在图像应该出现的位置。

对转场的一点视觉描述(其中 -> 表示转场):

ImageListTableViewController –> ImageViewController(有 UIImageView )

ImageListTableViewController.m

// The delegate here is the ImageViewController
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"Show Image"]) {
        [self setDelegate:segue.destinationViewController];
    }
}
// getting URL and calling the protocol method (in ImageViewController) which sets
// the image as an @property
#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSDictionary *imageDict = [self.imageArray objectAtIndex:indexPath.row];
    NSURL *imageURL = [FlickrFetcher urlForPhoto:imageDict format:FlickrPhotoFormatLarge];
    NSLog([imageURL description]);
    [self.delegate imageListTableViewController:self withURL:imageURL];
}

ImageViewController.m

#import "ImageViewController.h"

@implementation ImageViewController

@synthesize image = _image;
@synthesize imageView = _imageView;

- (void)imageListTableViewController:(ImageListTableViewController *)sender 
                             withURL:(NSURL *)imageURL;
{
    NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
    self.image = [UIImage imageWithData:imageData];
}

#pragma mark - View lifecycle


// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView
{
  // nothing
}


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.imageView setImage:self.image];
}


- (void)viewDidUnload
{
    [self setImageView:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

@end

关于发生了什么的任何想法？
谢谢!

Answer 1

不是真正使用委托(delegate)的正确方法。试试这个:
在 ImageViewController.h :

@property(nonatomic,strong) NSURL *imageURL;

在 ImageViewController.m

@synthesize imageURL;

删除 imageListTableViewController

更改viewDidLoad :

- (void)viewDidLoad
{
    [super viewDidLoad];
    NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
    self.image = [UIImage imageWithData:imageData];
}

添加到 viewDidUnload :

[self setImageURL:nil];

然后在你的ImageListTableViewController.m :
更改prepareForSegue :

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"Show Image"]) {
        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
        NSDictionary *imageDict = [self.imageArray objectAtIndex:indexPath.row];
        NSURL *imageURL = [FlickrFetcher urlForPhoto:imageDict format:FlickrPhotoFormatLarge];

        // Set the property on our Dest VC
        ImageViewController *ivc = segue.destinationViewController;
        ivc.imageURL = imageURL;

    }
}

更改您的 didSelectRowAtIndexPath :

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [self performSegueWithIdentifier:@"Show Image" sender:nil];
}

确保您已将该 Segue 连接到 VC 本身而不是 TableView。如果你不这样做，Segue 会在 didSelectRowAtIndexPath 之前被解雇。被解雇。在这种情况下，它不会产生影响，但对于真正的控制 - 养成连接到 VC 并在需要时调用 performSegue 的习惯。