Fetching specific Json data with NSDictionnary - ios

Question

I would like to fetch specific values in NSDictionnary with json data.
I would like to only fetch the first value for key "windspeedMiles" for example (in current_condition).
My Json data I've fetch is :
{
"data": {
"nearest_area": [
{
"distance_miles": "0.0",
"latitude": "54.500",
"longitude": "-8.500"
}
],
"request": [
{
"query": "Lat 54.50 and Lon -8.50",
"type": "LatLon"
}
],
"weather": [
{
"date": "2014-12-09",
"hourly": [
{
"cloudcover": "59",
"humidity": "84",
"precipMM": "0.1",
"pressure": "1024",
"sigHeight_m": "3.1",
"swellDir": "290",
"swellHeight_m": "3.0",
"swellPeriod_secs": "12.6",
"tempC": "5",
"tempF": "41",
"time": "0",
"visibility": "10",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "116",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0002_sunny_intervals.png"
}
],
"winddir16Point": "SSW",
"winddirDegree": "204",
"windspeedKmph": "34",
"windspeedMiles": "21"
},
{
"cloudcover": "84",
"humidity": "87",
"precipMM": "0.1",
"pressure": "1020",
"sigHeight_m": "0.6",
"swellDir": "240",
"swellHeight_m": "0.1",
"swellPeriod_secs": "12.4",
"tempC": "6",
"tempF": "42",
"time": "300",
"visibility": "10",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "119",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0003_white_cloud.png"
}
],
"winddir16Point": "SSW",
"winddirDegree": "193",
"windspeedKmph": "45",
"windspeedMiles": "28"
},
{
"cloudcover": "75",
"humidity": "91",
"precipMM": "0.4",
"pressure": "1016",
"sigHeight_m": "3.1",
"swellDir": "290",
"swellHeight_m": "3.0",
"swellPeriod_secs": "11.3",
"tempC": "7",
"tempF": "44",
"time": "600",
"visibility": "2",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "266",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0017_cloudy_with_light_rain.png"
}
],
"winddir16Point": "SSW",
"winddirDegree": "193",
"windspeedKmph": "54",
"windspeedMiles": "34"
},
{
"cloudcover": "0",
"humidity": "93",
"precipMM": "0.8",
"pressure": "1011",
"sigHeight_m": "1.0",
"swellDir": "250",
"swellHeight_m": "0.2",
"swellPeriod_secs": "10.6",
"tempC": "16",
"tempF": "61",
"time": "900",
"visibility": "10",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "113",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0001_sunny.png"
}
],
"winddir16Point": "SSW",
"winddirDegree": "202",
"windspeedKmph": "62",
"windspeedMiles": "39"
},
{
"cloudcover": "98",
"humidity": "95",
"precipMM": "6.6",
"pressure": "1006",
"sigHeight_m": "3.7",
"swellDir": "290",
"swellHeight_m": "3.6",
"swellPeriod_secs": "11.0",
"tempC": "18",
"tempF": "65",
"time": "1200",
"visibility": "7",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "302",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0018_cloudy_with_heavy_rain.png"
}
],
"winddir16Point": "SW",
"winddirDegree": "220",
"windspeedKmph": "64",
"windspeedMiles": "40"
},
{
"cloudcover": "89",
"humidity": "95",
"precipMM": "8.3",
"pressure": "1003",
"sigHeight_m": "4.3",
"swellDir": "290",
"swellHeight_m": "4.0",
"swellPeriod_secs": "10.9",
"tempC": "19",
"tempF": "65",
"time": "1500",
"visibility": "5",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "308",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0018_cloudy_with_heavy_rain.png"
}
],
"winddir16Point": "SW",
"winddirDegree": "234",
"windspeedKmph": "60",
"windspeedMiles": "38"
},
{
"cloudcover": "49",
"humidity": "73",
"precipMM": "1.5",
"pressure": "1004",
"sigHeight_m": "5.7",
"swellDir": "290",
"swellHeight_m": "5.3",
"swellPeriod_secs": "10.8",
"tempC": "7",
"tempF": "45",
"time": "1800",
"visibility": "10",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "353",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0009_light_rain_showers.png"
}
],
"winddir16Point": "W",
"winddirDegree": "261",
"windspeedKmph": "66",
"windspeedMiles": "41"
},
{
"cloudcover": "58",
"humidity": "73",
"precipMM": "0.5",
"pressure": "1005",
"sigHeight_m": "7.2",
"swellDir": "290",
"swellHeight_m": "6.7",
"swellPeriod_secs": "10.6",
"tempC": "5",
"tempF": "42",
"time": "2100",
"visibility": "10",
"waterTemp_C": "12",
"waterTemp_F": "53",
"weatherCode": "353",
"weatherIconUrl": [
{
"value": "http:\/\/cdn.worldweatheronline.net\/images\/wsymbols01_png_64\/wsymbol_0009_light_rain_showers.png"
}
],
"winddir16Point": "W",
"winddirDegree": "260",
"windspeedKmph": "79",
"windspeedMiles": "49"
}
],
"maxtempC": "19",
"mintempC": "5"
}
]
}
}
Here is my code :
Reports.m :
#import "Reports.h"
#interface Reports ()
#end
#implementation Reports
- (void)viewDidLoad
{
[super viewDidLoad];
NSURL *url = [NSURL URLWithString:#"http://api.worldweatheronline.com/free/v2/weather.ashx?q=Bundoran&format=json&num_of_days=5&key=e1caa114b7fba6f5bcea272e1fc77"];
NSData *data = [NSData dataWithContentsOfURL:url];
NSDictionary *dico = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
NSDictionary *wind = [dico objectForKey:#"windspeedMiles"];
NSLog(#"The current windspeedMiles is : %#", wind);
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

To grab that specific value in the structure you posted, you would access:
[[[[dico objectForKey:#"data"] objectForKey:#"current_condition"] objectAtIndex:0] objectForKey:#"windspeedMiles"]
You just need to look at your structure. When you get your dictionary with the JSONObjectWithData it will give you an NSDictionary for every set of curly braces, and an NSArray for every set of square ones.
Because everything in your JSON is a sub-object of "Data", I would recommend creating your original NSDictionary as:
NSDictionary *dico = [[NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil] objectForKey:#"data"];
This way you don't have to keep referencing the "data" dictionary.

Answer 2

Your intended key resides in a nested NSDictionary object, so you can't retrieve it using:
NSDictionary *wind = [dico objectForKey:#"windspeedMiles"];
NSLog(#"The current windspeedMiles is : %#", wind);
Use:
NSDictionary *wind = [dico[#"data"][#"condition"] objectAtIndex:0];
NSLog(#"The current windspeedMiles is : %#", wind[#"windspeedMiles"]);