如何在Objective-C中解析JSON [英] How to parse JSON in Objective-C

问题描述

我有这个json字符串

i have this json string

{
    "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/",
    "city": [
        {
            "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ABJ/",
            "agencyCollection": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ABJ/agencyCollection/"
            },
            "codecit": "ABJ",
            "country": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ABJ/country/"
            },
            "namecit": "ABIDJAN"
        },
        {
            "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/",
            "agencyCollection": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/agencyCollection/",
                "agency": [
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/agencyCollection/3/"
                    },
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/agencyCollection/4/"
                    }
                ]
            },
            "codecit": "ALG",
            "country": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/ALG/country/"
            },
            "namecit": "ALGER"
        },
        {
            "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/",
            "agencyCollection": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/agencyCollection/",
                "agency": [
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/agencyCollection/5/"
                    },
                    {
                        "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/agencyCollection/6/"
                    }
                ]
            },
            "codecit": "AMS",
            "country": {
                "@uri": "http://localhost:8080/TunisairRESTful/resources/cities/AMS/country/"
            },
            "namecit": "AMSTERDAM"
        }
    ]
}

我想解析它，我写了这段代码

I want to parse it, I wrote this code

NSString *myJSON = [[NSString alloc] initWithContentsOfFile:responseString encoding:NSUTF8StringEncoding error:NULL];   
NSDictionary *json    = [myJSON JSONValue];
//NSLog(responseString);
NSArray *citysList    =  [json objectForKey:@"city"];
NSLog(@"ok");
NSLog(@" number of element : %@", [citysList count]);

但是我有0个元素，请帮助

But I have 0 number of element , help please

推荐答案

迈克尔是正确的.这是更详细的答案:

Michael is right. Here's a more detailed answer:

initWithContentsOfFile采用包含文件路径的字符串(例如"/users/mehdi/documents/myFile.txt").您似乎正在传递您的实际JSON字符串，这不是文件路径.结果，initWithContentsOfFile可能返回nil.

initWithContentsOfFile takes a string containing a file path (e.g. "/users/mehdi/documents/myFile.txt"). You seem to be passing in your actual JSON string, which isn't a file path. As a result, initWithContentsOfFile is probably returning nil.

通过询问以下内容进行确认:

Check this by asking:

if (myJSON == nil) NSLog(@"myJSON variable == nil!");

如果为nil，则您的代码还将json和citysList设置为nil.

If it is nil, then your code is also setting json and citysList to nil.

尝试一下:

NSDictionary *json    = [responseString JSONValue];
NSArray *citysList    =  [json objectForKey:@"city"];
NSLog(@" number of element : %d", [citysList count]);

这篇关于如何在Objective-C中解析JSON的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！