iphone - 如何用字符串分隔的组件进行json解析

Question

我是解析 JSON 的新手，我正在尝试一个简单的任务，即从预报天气 json 文件中检索 URL。

这里我解析了 json 并且我 NSLog 了数据的每个组成部分的内容:

NSError *myError = nil;
NSDictionary *res = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableLeaves  error:&myError];

NSArray *data =  [res objectForKey:@"data"];
NSLog(@"data=%@",data);

NSArray *results =  [data valueForKey:@"weather"];
NSLog(@"weather=%@",results);

NSArray *results1 =  [results valueForKey:@"tempMaxC"];
NSLog(@"tempMaxC=%@",results1);

NSArray *results2 =  [results1 valueForKey:@"weatherIconUrl"];
NSLog(@"weatherIconUrl=%@",results2);

问题是当我得到 WeatherIconUrl 时它带有这种格式

"http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0001_sunny.png"

我无法在没有引号的情况下获取 url 本身，我尝试使用 nsrange 和 componentsSeparatedByString 但它总是给我这个错误:

[__NSArrayI componentsSeparatedByString:]: unrecognized selector sent to instance 

来自服务器的 JSON:

{
    "data": {
        "current_condition": [
            {
                "cloudcover": "0",
                "humidity": "73",
                "observation_time": "12:19 PM",
                "precipMM": "0.0",
                "pressure": "1021",
                "temp_C": "23",
                "temp_F": "73",
                "visibility": "10",
                "weatherCode": "113",
                "weatherDesc": [
                    {
                        "value": "Sunny"
                    }
                ],
                "weatherIconUrl": [
                    {
                        "value": "http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0001_sunny.png"
                    }
                ],
                "winddir16Point": "NW",
                "winddirDegree": "320",
                "windspeedKmph": "17",
                "windspeedMiles": "11"
            }
        ],
        "request": [
            {
                "query": "Fanzeres, Portugal",
                "type": "City"
            }
        ],
        "weather": [
            {
                "date": "2012-09-12",
                "precipMM": "0.0",
                "tempMaxC": "28",
                "tempMaxF": "83",
                "tempMinC": "17",
                "tempMinF": "63",
                "weatherCode": "113",
                "weatherDesc": [
                    {
                        "value": "Sunny"
                    }
                ],
                "weatherIconUrl": [
                    {
                        "value": "http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0001_sunny.png"
                    }
                ],
                "winddir16Point": "NW",
                "winddirDegree": "312",
                "winddirection": "NW",
                "windspeedKmph": "16",
                "windspeedMiles": "10"
            },
            {
                "date": "2012-09-13",
                "precipMM": "0.0",
                "tempMaxC": "33",
                "tempMaxF": "91",
                "tempMinC": "17",
                "tempMinF": "63",
                "weatherCode": "113",
                "weatherDesc": [
                    {
                        "value": "Sunny"
                    }
                ],
                "weatherIconUrl": [
                    {
                        "value": "http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0001_sunny.png"
                    }
                ],
                "winddir16Point": "N",
                "winddirDegree": "8",
                "winddirection": "N",
                "windspeedKmph": "10",
                "windspeedMiles": "6"
            }
        ]
    }
}

抱歉我的英语不好，如果我做错了请纠正我，在此先感谢

Answer 1

从 @"weatherIconUrl"获取数组时使用 objectForKey 而不是 valueForKey 然后将字符串获取到 NSString 例如

NSString *weatherIconUrlString = [results2 objectAtIndex:0]

要检查这是一个有效的 url，请使用 NSURLConnection 的 canHandleRequest 方法，例如

NSURL *url = [NSURL URLWithString:weatherIconUrlString];
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url 
BOOL canGo = [NSURLConnection canHandleRequest:request];