访问 NSDictionary 值 Objective C

Question

我的字典看起来像这样。

{
 thread = "{
 \"uuid\": \"e9290344dee38c42782\",
 \"site_full\": \"www.independent.co.uk\",
 \"main_image\":\"http://www.independent.co.uk/incoming/article10498560.ece/binary/original/39-tea-party-ap.jpg\"
 }";
}  

[newDict valueForKeyPath:@"thread.main_image"];

我正在尝试这样访问它，但它我可以获得线程之外的所有其他值，但不能获得线程中的嵌套值。感谢任何帮助。

编辑

      for (int i=0;i < [responseObject count];i++) {
                NSDictionary* newDict = (NSDictionary*)responseObject[i];

                    if ([(NSString*)[newDict valueForKey:@"title"]  isEqualToString: @""] || [newDict valueForKey:@"title"]== Nil)  {
                        NSLog(@"Image or Title Text is null");
                    }
                    else{
                    NewsFeed* newsData = [NewsFeed new];
                    newsData.newsSource = [newDict valueForKeyPath:@"thread.site"];
                    newsData.newsImageLink = [newDict valueForKeyPath:@"thread.main_image"];
              //these three work fine
                    newsData.newsTitle = [newDict valueForKeyPath:@"title"];
                    newsData.newsText = [newDict valueForKeyPath:@"text"];
                    newsData.newsDate = [newDict valueForKeyPath:@"published"]; 
              //
                    NSLog(@"news Source :: %@ \n and news ImageLink:: %@ \n news Title %@  \nnews Text:: %@ \n news Date::  %@  ",newsData.newsSource,newsData.newsImageLink,newsData.newsTitle,newsData.newsText,newsData.newsDate);
                    [NewsData addObject:newsData];
                    }


        }

Answer 1

看起来存储在索引下标"thread" 处的对象不是假设的NSDictionary，而是似乎是NSString 的一个实例。

这很微妙，但请查看根级字典中键 "thread" 处对象的打印值：

This is an NSDictionary with one key: "thread"
|
|         This is an NSString object, see the quotes (")?
|         |
V         |                     Notice that these other keys/values have their quotes (") escaped with backslash?
{         V                     |
 thread = "{                    V
 \"uuid\": \"e9290344dee38c42782\",
 \"site_full\": \"www.independent.co.uk\",
 \"main_image\":\"http://www.independent.co.uk/incoming/article10498560.ece/binary/original/39-tea-party-ap.jpg\"
 }";
} ^
  |
  Here is the end of the NSString, again we see quotes (")

假设这确实是问题所在，您需要将字符串转换为实际字典，您应该可以轻松做到这一点using JSON serialization which this question/answer should help guide you to do.

一旦这个问题得到纠正，您对valueForKeyPath: 的使用应该是正确的并且应该立即开始工作。

Answer 2

试试这个现代的 Objective-C 代码：

NSDictionary *myDict = @{@"thread" : @{@"uuid" : @"e9290344dee38c42782", @"site_full" : @"www.independent.co.uk", @"main_image" : @"http://www.independent.co.uk/incoming/article10498560.ece/binary/original/39-tea-party-ap.jpg"}};
NSLog(@"Image = %@", myDict[@"thread"][@"main_image"]);

编辑：在附加调试器屏幕截图的 OP 响应后：