在iOS中解析JSON圖片網址錯誤

Question

我正在嘗試解析一個JSON文件，其中包含一些指向圖像的鏈接以及一些標題和時間。

這是我的代碼：

#import "PicturesViewController.h"
#import "DemoViewController.h"
#import "SecondViewController.h"
#import "AppDelegate.h"
#import "RNBlurModalView.h"
#import "PictureJSON.h"
#import "HMSegmentedControl.h"

@interface PicturesViewController ()
{
    NSInteger refreshIndex;
    NSArray *images;
}

@end

@implementation PicturesViewController

- (void)viewDidLoad
{

    HMSegmentedControl *segmentedControl = [[HMSegmentedControl alloc] initWithSectionTitles:@[@"Instagram", @"Hashtags", @"Facebook"]];
    [segmentedControl setFrame:CGRectMake(10, 10, 300, 60)];
    [segmentedControl addTarget:self action:@selector(segmentedControlChangedValue:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:segmentedControl];

    [super viewDidLoad];
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Menu" style:UIBarButtonItemStyleBordered target:self action:@selector(showMenu)];

    UIPanGestureRecognizer *gestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(swipeHandler:)];
    [self.view addGestureRecognizer:gestureRecognizer];

    [self issueLoadRequest];
}

- (void)swipeHandler:(UIPanGestureRecognizer *)sender
{
    [[self sideMenu] showFromPanGesture:sender];
}

- (void)segmentedControlChangedValue:(HMSegmentedControl *)segmentedControl1 {
    [self issueLoadRequest];
}

- (void)segmentedControlSelectedIndexChanged:(id)sender
{
    [self issueLoadRequest];
}

#pragma mark -
#pragma mark Button actions

- (void)showMenu
{
    [[self sideMenu] show];
}

#pragma mark - Table view data source


- (void)issueLoadRequest
{
    // Dispatch this block asynchronosly. The block gets JSON data from the specified URL and performs the proper selector when done.
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData* data = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://my-site/pictureparse.php?name=Name"]];
        [self performSelectorOnMainThread:@selector(receiveData:) withObject:data waitUntilDone:YES];
    });
}

- (void)receiveData:(NSData *)data {
    // When we have the data, we serialize it into native cocoa objects. (The outermost element from twitter is
    // going to be an array. I JUST KNOW THIS. Reload the tableview once we have the data.
    self.tweets = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
    [self.myTableView reloadData];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return self.tweets.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *simpleTableIdentifier = @"PictureJSON";

    PictureJSON *cell = (PictureJSON *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"PictureJSON" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }

    // The element in the array is going to be a dictionary. I JUST KNOW THIS. The key for the tweet is "text".
    NSDictionary *tweet = [self.tweets objectAtIndex:indexPath.row];
    NSLog(@"%@", [cell class]);
    cell.instaImage = [tweet objectForKey:@"link"];
    cell.titleLabel.text = [tweet objectForKey:@"title"];
    cell.timeLabel.text = [tweet objectForKey:@"published"];

    return cell;
}

但是，當我啟動我的應用程序時，出現此錯誤：

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<PicturesViewController 0x758bf70> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key instaImage.'

我的JSON文件如下所示：

[
    {
        "link": "http://link.com/picture.jpg",
        "title": "title",
        "published": "0:12 PM 21/10"
    },
    {
        "link": "http://link.com/picture.jpg",
        "title": "title",
        "published": "0:09 AM 21/10"
    }
]

我究竟做錯了什么？

Answer 1

我認為您必須檢查屬性instaImage。 我認為您正在訪問未在筆尖中定義的屬性。

Answer 2

拳頭試圖調試這個。 從崩潰日志中，我認為您在自定義單元上做錯了。 首先檢查您的PictureJSON連接。 並檢查您的文件所有者，它應該是您的自定義單元格。 您可以使用breakpoint確認。 如果在創建單元格時遇到錯誤，則可以采用上述解決方案。

Answer 3

我認為問題不在於您的JSON序列化，而是由於您的static NSString *simpleTableIdentifier = @"PictureJSON";

確保已為您的自定義單元分配了此標識符！