在 iOS 错误中解析 JSON 图像 url

Posted 2023-03-04

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【中文标题】在 iOS 错误中解析 JSON 图像 url【英文标题】：Parsing JSON image urls in iOS error 【发布时间】：2013-10-21 11:54:36 【问题描述】：

我正在尝试解析一个 JSON 文件，其中包含一些图像链接以及一些标题和时间。

这是我的代码：

#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;

但是当我启动我的应用程序时，我收到了这个错误：

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"
    
]

我做错了什么？

【问题讨论】：

【参考方案1】：

我认为您必须检查属性 instaImage。我认为您正在访问您尚未在 nib 中定义的属性。

【讨论】：

如果单元格不是单元格，那么单元格的其他两个属性也应该抛出异常。【参考方案2】：

拳头尝试调试这个。从崩溃日志中，我认为您对自定义单元做错了。首先检查 PictureJSON 的连接。并检查您的文件所有者，它应该是您的自定义单元格。您可以使用 breakpoint 确认这一点。如果您在创建单元格时遇到错误，那么上面就是解决方案。

【讨论】：

为什么要投反对票？至少花点力气说明原因。【参考方案3】：

我认为问题不在于您的 JSON 序列化，从您的日志来看，这次崩溃是因为您的 static NSString *simpleTableIdentifier = @"PictureJSON";

确保您已为您的自定义单元格分配了此标识符！

【讨论】：