獲得JSON值

-2

我有麻煩訪問JSON對象從一個I在教程中不同：獲得JSON值

我有此JSON在指南中，我以下：

{ 
"coord": { 
    "lon": -0.13, 
    "lat": 51.51 
}, 
"weather": [{ 
    "id": 803, 
    "main": "Clouds", 
    "description": "broken clouds", 
    "icon": "04d" 
}], 
"base": "cmc stations", 
"main": { 
    "temp": 285.325, 
    "pressure": 1024.67, 
    "humidity": 95, 
    "temp_min": 285.325, 
    "temp_max": 285.325, 
    "sea_level": 1034.69, 
    "grnd_level": 1024.67 
}, 
"wind": { 
    "speed": 7.46, 
    "deg": 246.001 
}, 
"clouds": { 
    "all": 76 
}, 
"dt": 1448967456, 
"sys": { 
    "message": 0.0027, 
    "country": "GB", 
    "sunrise": 1448955837, 
    "sunset": 1448985295 
}, 
"id": 2643743, 
"name": "London", 
"cod": 200

}

而且從它那裏得到的主要價值我用這個代碼：

NSURLRequest *urlrequest =[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://api.openweathermap.org"]]; 

NSURLSession *session = [NSURLSession sharedSession]; 

[[session dataTaskWithRequest:urlrequest completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) { 
    NSMutableDictionary *allData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil]; 

    NSString* currentWeather = nil; 

    NSArray* weather = allData[@"weather"]; 

    for (NSDictionary* weatherDictionary in weather){ 
     currentWeather = weatherDictionary[@"main"]; 
    } 

    [self setImageAndTextWithWeather:currentWeather]; 

    //NSLog(allData[@"temp_c"]); 

}] resume];

，這是工作得很好。但現在我想從另一個來源是這樣的訪問JSON對象：

{ 
"response": { 
    "version": "0.1", 
    "termsofService": "http://www.wunderground.com/weather/api/d/terms.html", 
    "features": { 
     "conditions": 1 
    } 
}, 
"current_observation": { 
    "image": { 
     "url": "http://icons-ak.wxug.com/graphics/wu2/logo_130x80.png", 
     "title": "Weather Underground", 
     "link": "http://www.wunderground.com" 
    }, 
    "display_location": { 
     "full": "San Francisco, CA", 
     "city": "San Francisco", 
     "state": "CA", 
     "state_name": "California", 
     "country": "US", 
     "country_iso3166": "US", 
     "zip": "94101", 
     "latitude": "37.77500916", 
     "longitude": "-122.41825867", 
     "elevation": "47.00000000" 
    }, 
    "observation_location": { 
     "full": "SOMA - Near Van Ness, San Francisco, California", 
     "city": "SOMA - Near Van Ness, San Francisco", 
     "state": "California", 
     "country": "US", 
     "country_iso3166": "US", 
     "latitude": "37.773285", 
     "longitude": "-122.417725", 
     "elevation": "49 ft" 
    }, 
    "estimated": {}, 
    "station_id": "KCASANFR58", 
    "observation_time": "Last Updated on June 27, 5:27 PM PDT", 
    "observation_time_rfc822": "Wed, 27 Jun 2012 17:27:13 -0700", 
    "observation_epoch": "1340843233", 
    "local_time_rfc822": "Wed, 27 Jun 2012 17:27:14 -0700", 
    "local_epoch": "1340843234", 
    "local_tz_short": "PDT", 
    "local_tz_long": "America/Los_Angeles", 
    "local_tz_offset": "-0700", 
    "weather": "Partly Cloudy", 
    "temperature_string": "66.3 F (19.1 C)", 
    "temp_f": 66.3, 
    "temp_c": 19.1, 
    "relative_humidity": "65%", 
    "wind_string": "From the NNW at 22.0 MPH Gusting to 28.0 MPH", 
    "wind_dir": "NNW", 
    "wind_degrees": 346, 
    "wind_mph": 22.0, 
    "wind_gust_mph": "28.0", 
    "wind_kph": 35.4, 
    "wind_gust_kph": "45.1", 
    "pressure_mb": "1013", 
    "pressure_in": "29.93", 
    "pressure_trend": "+", 
    "dewpoint_string": "54 F (12 C)", 
    "dewpoint_f": 54, 
    "dewpoint_c": 12, 
    "heat_index_string": "NA", 
    "heat_index_f": "NA", 
    "heat_index_c": "NA", 
    "windchill_string": "NA", 
    "windchill_f": "NA", 
    "windchill_c": "NA", 
    "feelslike_string": "66.3 F (19.1 C)", 
    "feelslike_f": "66.3", 
    "feelslike_c": "19.1", 
    "visibility_mi": "10.0", 
    "visibility_km": "16.1", 
    "solarradiation": "", 
    "UV": "5", 
    "precip_1hr_string": "0.00 in (0 mm)", 
    "precip_1hr_in": "0.00", 
    "precip_1hr_metric": " 0", 
    "precip_today_string": "0.00 in (0 mm)", 
    "precip_today_in": "0.00", 
    "precip_today_metric": "0", 
    "icon": "partlycloudy", 
    "icon_url": "http://icons-ak.wxug.com/i/c/k/partlycloudy.gif", 
    "forecast_url": "http://www.wunderground.com/US/CA/San_Francisco.html", 
    "history_url": "http://www.wunderground.com/history/airport/KCASANFR58/2012/6/27/DailyHistory.html", 
    "ob_url": "http://www.wunderground.com/cgi-bin/findweather/getForecast?query=37.773285,-122.417725" 
}

} 現在我怎樣才能temp_c價值？

我做過NSLog(allData)和@"temp_c" : (double)26.9 可能是我想要存儲在NSString double value？

我嘗試將當前代碼中的值更改爲allData[@"current_observation"]和weatherDictonary[@"temp_c"]，但我總是遇到錯誤。

來源

2015-12-01 Jack

你能解釋一下你認爲'for'循環在做什麼嗎？ – trojanfoe

如果你可以在這裏粘貼你的整個JSON？ – Stefan

@trojanfoe我真的不知道，我有一個更好的方式訪問它請告訴我。 – Jack

「current_observation」不包含數組，它包含字典

NSDictionary* weather = allData[@"current_observation"]; 
NSString *currentWeather = nil; 
NSString *currentTemp = nil; 
if (weather[@"temperature_string"]){ 
    currentWeather = weather[@"temperature_string"]; 
} 
if (weather[@"temp_c"]) { 
    currentTemp = [NSString stringWithFormat:@"%@",weather[@"temp_c"]]; 
}

「temp_c」是一個數字，而不是字符串，所以你需要將它轉換爲字符串。

來源

2015-12-01 12:28:09

Ooooh ok！得到它了！非常感謝解釋！ – Jack

通過使用'if'來執行'NSString * currentWeather = weather [@「temperature_string」];'等等，可以使它變得更簡單。你會得到相同的結果。 – trojanfoe

當然，你可以這樣做，但使用if語句可以保證安全，特別是如果你從第三方獲取數據。 –

-1

這是不是很好的解釋您的問題，在以前的評論。您有NSDictionary不是NSArray。簡單的解決方案是迭代：

NSString *weather =[NSString stringWithFormat:@"%@", [allData objectForKeyPath:@"temp_c"]];

來源

2015-12-01 12:34:39

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