objectForKey 处的空数组导致 iPhone 应用程序崩溃

发布于 2024-11-02 03:31:03 字数 1254 浏览 0 评论 0原文

我有一个从 JSON 创建的数组。该数组如下所示：

[
    {
        "img": "images/photo_10.jpg", 
        "title": "None", 
        "photo_comments": [
            {
                "body": "my comment", 
                "author": "john", 
                "created": "2011-04-17 14:21:11"
            }
        ], 
        "id": 24
    }, 
    {
        "img": "images/photo_8.jpg", 
        "title": "None", 
        "photo_comments": [], 
        "id": 22
    }


]

我将数组传递给一个函数，该函数枚举字典并创建一个字符串，然后将其添加到注释数组中。我的代码如下所示：

    -(NSArray *)formatCommentArray:(NSArray *)array  
{

    NSMutableArray *comments = [[[NSMutableArray alloc] init] autorelease];

    for (NSDictionary *photo in array)
    {   


           for( NSDictionary *comment in [photo objectForKey:@"photo_comments"])
           {

               NSString *commentString = [NSString stringWithFormat:@"%@: %@", 
                                           [comment objectForKey:@"author"], [comment objectForKey:@"body"]];



               [comments addObject:commentString];


           }




    return comments;

}

该应用程序似乎崩溃了，因为并非所有照片都有注释，当它到达空数组时，它就会停止。我尝试了一些“if 语句”和其他一些技巧，但没有成功。我成功地使用此代码创建了图像数组，但显然“img”键的值不是带有字典的数组。任何帮助将不胜感激。提前致谢。

原文

I have an array that gets created from JSON. The array looks like this:

[
    {
        "img": "images/photo_10.jpg", 
        "title": "None", 
        "photo_comments": [
            {
                "body": "my comment", 
                "author": "john", 
                "created": "2011-04-17 14:21:11"
            }
        ], 
        "id": 24
    }, 
    {
        "img": "images/photo_8.jpg", 
        "title": "None", 
        "photo_comments": [], 
        "id": 22
    }


]

I pass the array to a function that enumerates thru the dictionary and creates a string then adds it to a comments array. My code looks like this:

    -(NSArray *)formatCommentArray:(NSArray *)array  
{

    NSMutableArray *comments = [[[NSMutableArray alloc] init] autorelease];

    for (NSDictionary *photo in array)
    {   


           for( NSDictionary *comment in [photo objectForKey:@"photo_comments"])
           {

               NSString *commentString = [NSString stringWithFormat:@"%@: %@", 
                                           [comment objectForKey:@"author"], [comment objectForKey:@"body"]];



               [comments addObject:commentString];


           }




    return comments;

}

The app appears to crash because not all my photos have comments and when it gets to an empty array it comes to a halt. I've tried some "if statements" and a few other tricks to no avail. I used this code successfully to create an array of images, but obviously the value for the "img" key was NOT an array with a dictionary. Any help would be greatly appreciated. Thanks in advance.

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偏爱你一生 2024-11-09 03:31:03

好吧，[[comment objectForKey:@"photo_comments"] objectForKey:@"author"] 正在尝试在数组上使用 objectForKey，但这是行不通的。查看您的 json，photo_comments 是一个（可能为空）列表，包含对象。您还需要一个列表循环。

for (NSDictionary *photo in array)
{
  // do stuff with photo.img, photo.title etc

  for (NSDictionary *comment in [photo objectForKey:@"photo_comments"])
  {
    // do stuff with comment.author, comment.body etc
  }
}

（添加错误检查以适应。）

well, [[comment objectForKey:@"photo_comments"] objectForKey:@"author"] is trying to use objectForKey on an array, which won't work. Looking at your json, photo_comments is a (potentially empty) list, containing objects. You need one more list loop in there.

for (NSDictionary *photo in array)
{
  // do stuff with photo.img, photo.title etc

  for (NSDictionary *comment in [photo objectForKey:@"photo_comments"])
  {
    // do stuff with comment.author, comment.body etc
  }
}

(add error checking to suit.)

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