Retrieving and displaying JSON data from URL (objective-C) - iphone

Question

I am doing my homework to retrieve and display information about current weather from a JSON object using singleton pattern and ASIHTTPRequest.
The data from the URL in JSON format looks like this:
{ "data":
{ "current_condition":
[ {
"cloudcover": "51",
"humidity": "66",
"observation_time": "12:44 PM",
"precipMM": "0.0",
"pressure": "1002",
"temp_C": "30",
"temp_F": "86",
"visibility": "10",
"weatherCode": "116",
"weatherDesc": [ {"value": "Partly Cloudy" } ],
"weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0004_black_low_cloud.png" } ],
"winddir16Point": "S",
"winddirDegree": "170",
"windspeedKmph": "19",
"windspeedMiles": "12" } ],
"request": [ {
"query": "Lat 22.49 and Lon 114.14",
"type": "LatLon" } ],
"weather": [ {
"date": "2012-06-06",
"precipMM": "0.0",
"tempMaxC": "30",
"tempMaxF": "86",
"tempMinC": "26",
"tempMinF": "79",
"weatherCode": "113",
"weatherDesc": [ {"value": "Sunny" } ],
"weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0001_sunny.png" } ],
"winddir16Point": "SE",
"winddirDegree": "136",
"winddirection": "SE",
"windspeedKmph": "17",
"windspeedMiles": "11"
},
{
"date": "2012-06-07",
"precipMM": "0.1",
"tempMaxC": "30",
"tempMaxF": "87",
"tempMinC": "27",
"tempMinF": "80",
"weatherCode": "113",
"weatherDesc": [ {"value": "Sunny" } ],
"weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0001_sunny.png" } ],
"winddir16Point": "ESE",
"winddirDegree": "121",
"winddirection": "ESE",
"windspeedKmph": "15",
"windspeedMiles": "10"
},
{
"date": "2012-06-08",
"precipMM": "2.1",
"tempMaxC": "31",
"tempMaxF": "87",
"tempMinC": "27",
"tempMinF": "81",
"weatherCode": "116",
"weatherDesc": [ {"value": "Partly Cloudy" } ],
"weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0002_sunny_intervals.png" } ],
"winddir16Point": "SSE",
"winddirDegree": "166",
"winddirection": "SSE",
"windspeedKmph": "17",
"windspeedMiles": "11"
},
{
"date": "2012-06-09",
"precipMM": "2.8",
"tempMaxC": "32",
"tempMaxF": "89",
"tempMinC": "28",
"tempMinF": "82",
"weatherCode": "176",
"weatherDesc": [ {"value": "Patchy rain nearby" } ],
"weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0009_light_rain_showers.png" } ],
"winddir16Point": "SSW",
"winddirDegree": "198",
"winddirection": "SSW",
"windspeedKmph": "17",
"windspeedMiles": "11"
},
{
"date": "2012-06-10",
"precipMM": "13.0",
"tempMaxC": "32",
"tempMaxF": "90",
"tempMinC": "28",
"tempMinF": "82",
"weatherCode": "116",
"weatherDesc": [ {"value": "Partly Cloudy" } ],
"weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0002_sunny_intervals.png" } ],
"winddir16Point": "SW",
"winddirDegree": "220",
"winddirection": "SW",
"windspeedKmph": "22",
"windspeedMiles": "14"
} ]
}
}
In my AppData.m, the code looks like this:
- (void)requestFinished:(ASIHTTPRequest *)request {
NSData* responseData = [request responseData];
NSDictionary* resultDict = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:NULL];
NSDictionary* dataDict = [resultDict objectForKey:#"data"];
NSArray* myArray = [dataDict objectForKey:#"weather"];
if(weatherDataArray == nil)
weatherDataArray = [[NSMutableArray alloc] init];
[weatherDataArray setArray:myArray];
}
In myWeather.m, the code like this :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
myWeatherDataCell *cell = [tableView dequeueReusableCellWithIdentifier:#"myWeatherDataCell"];
// get the view controller's info dictionary based on the indexPath's row
NSDictionary* item = [[AppData sharedData].weatherDataArray objectAtIndex:indexPath.row];
cell.maxTempLabel.text = [item objectForKey:#"tempMaxC"];
cell.minTempLabel.text = [item objectForKey:#"tempMinC"];
cell.dateLabel.text = [item objectForKey:#"date"];
cell.detailTextLabel.adjustsFontSizeToFitWidth = YES;
NSArray* weatherIconUrl = [item objectForKey:#"weatherIconUrl"];
NSDictionary* value = [weatherIconUrl valueForKey:#"value"];
NSString* urlString = [NSString stringWithFormat:#"%#",value];
NSData* url = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:urlString]];
cell.iconView.image = [UIImage imageWithData:url];
NSLog(#"weatherIconUrl" "%#",urlString);
return cell;
}
The tableview can show
cell.maxTempLabel.text = [item objectForKey:#"tempMaxC"];
cell.minTempLabel.text = [item objectForKey:#"tempMinC"];
cell.dateLabel.text = [item objectForKey:#"date"];
Except the iconview.image.
I try to use NSlog for
NSString* urlString = [NSString stringWithFormat:#"%#",value];
It can show looks like this:
2012-11-11 11:51:46.100 MyWeather[1583:1a603] weatherIconUrl(
"http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0001_sunny.png"
)
2012-11-11 11:51:46.101 MyWeather[1583:1a603] weatherIconUrl(
"http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0017_cloudy_with_light_rain.png"
)
2012-11-11 11:51:46.102 MyWeather[1583:1a603] weatherIconUrl(
"http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0001_sunny.png"
)
2012-11-11 11:51:46.102 MyWeather[1583:1a603] weatherIconUrl(
"http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0001_sunny.png"
)
2012-11-11 11:51:46.103 MyWeather[1583:1a603] weatherIconUrl(
"http://www.worldweatheronline.com/images/wsymbols01_png_64/wsymbol_0004_black_low_cloud.png"
)
But when I try to NSLog NSData* url, the result is (null).
So I think I am stuck in when "NSString* urlString" pass the data to "NSData* url".

Answer 1

As I said in my comment, your variable, "weatheIconURL", is actually an array with one object (a dictionary) in it, so you can use lastObject to fix that line. So those few lines need to be changed to:
NSDictionary* weatherIconUrl = [[item objectForKey:#"weatherIconUrl"] lastObject];
NSString* urlString = [weatherIconUrl valueForKey:#"value"];
NSData* url = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:urlString]];
cell.iconView.image = [UIImage imageWithData:url];

Answer 2

you can use JsonKit
to parse Jdon data and convert it into dictionary after getting the response from ASSIHTTPRequest
like this
- (void) requestFinished:(ASIHTTPRequest *)request {
// Use when fetching text data
NSString *responseString = [request responseString];
// Json dictionary
NSDictionary *resultsDictionary = [responseString objectFromJSONString];
}
in your case if you wanna get the cloudcover you may say
NSString *cloudCover =[[[resultsDictionary objectForKey:#"data"]objectForKey:#"current_condition"] objectAtIndex:0];
hope that helps