I am from php domain, and now learning ios coding. I want to make a view with one part showing user info, and a table showing friends details.
I can get the json Logged correctly.
My json looks like this:
{"Me":
{"username":"aVC",
"userID":1
},
"Friends":
[{"username":"Amm",
"userID":2
},...
]
}
Here is what I use.
NSError *error;
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
NSDictionary *json = (NSDictionary*)[NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
NSLog(#"jS: %#", json);
this works fine. I want to seperate the two sections (Me, and friends), and then use it to fill tables. Can someone throw some ideas?
NOTE: I am not using any frameworks. Just NSJSONSerialization.
Try adding this code after obtaining the json dictionary:
NSDictionary *me = [json objectForKey:#"Me"];
NSArray *friends = [json objectForKey:#"Friends"];
This should let you pull the information from the #"Me" and #"Friends" into separate variables.
Related
This has got to be something obvious that I am doing wrong. I have been banging my head against a wall trying to figure out what is going on. I already have this json parsing done in the android version of my app, now trying to parse this simple json in xcode and can't get it done.
NSError *myError = nil;
NSDictionary *res = [NSJSONSerialization JSONObjectWithData:self.responseData options:kNilOptions error:&myError];
NSLog([res objectForKey:#"Date"]);
This code get me the "unrecognized selector sent to instance" error.
Here is the json data and you can see Date is one of the objects:
[{"Date":"2016-06-17T22:56:33.0811255-05:00"}]
Thanks in advance for any help on this issue. I've tried to simplify this post, but if more info is needed I will try and quickly provide.
http://i.stack.imgur.com/Y5fsT.png
JSONObjectWithData is returning an array of dictionaries and not a dictionary. Your print out of the raw JSON confirms this:
[{"Date":"2016-06-17T22:56:33.0811255-05:00"}] // This is an array
However you're attempting to treat that response object like a dictionary. In doing so you're calling a dictionary method (objectForKey:) on an array. This results in a crash. Try something like this:
NSError *error = nil;
id responseObject = [NSJSONSerialization JSONObjectWithData:self.responseData options:kNilOptions error:&error];
if (error)
{
// Handle error
return;
}
NSLog(#"%#", responseObject);
if ([responseObject isKindOfClass:[NSArray class]])
{
NSArray *responseArray = (NSArray *)responseObject;
for (id item in responseArray)
{
NSLog(#"%#", item);
if ([item isKindOfClass:[NSDictionary class]])
{
NSDictionary *dictionary = (NSDictionary *)item;
NSString *dateString = [dictionary objectForKey:#"Date"];
NSLog(#"%#", dateString);
}
}
}
else
{
// responseObject is not an array...
}
I'm pretty sure this is because you should first set res as [NSDictionary]. Then pick the first element in that array and then get objectForKey: "Date". Normal JSON Data starts with a {, this starts with a [. Which means it's an array.
You can see it for yourself in the screenshot when it says #: 1 Element . THEN it says 1 key/value pair. The NSDictionary is inside an array.NSError
Try this code:
*myError = nil;
[NSDictionary] *res = [NSJSONSerialization JSONObjectWithData:self.responseData options:kNilOptions error:&myError];
if (res.count > 0) {
NSLog([res[0] objectForKey:#"Date"]);
}
I'm trying to get one value from JSON. JSON is located in NSString and it looks like this:
{"coord":{"lon":-122.38,"lat":37.57},"weather":[{"id":300,"main":"Drizzle","description":"Lekka mżawka","icon":"09d"}],"base":"stations","main":{"temp":304.74,"pressure":1017,"humidity":35,"temp_min":300.15,"temp_max":307.59},"visibility":16093,"wind":{"speed":6.7,"deg":250},"clouds":{"all":75},"dt":1437346641,"sys":{"type":1,"id":478,"message":0.0615,"country":"US","sunrise":1437311022,"sunset":1437362859},"id":5357155,"name":"Hillsborough","cod":200}
I'm interested in getting "temp". How should I do that?
Assuming your JSON string was stored as a NSString named JSONString:
NSError *error;
NSDictionary *keys = [NSJSONSerialization JSONObjectWithData:[JSONString dataUsingEncoding:NSUTF8StringEncoding]
options:NSJSONReadingMutableContainers
error:&error];
NSLog(#"temp = %#", keys[#"main"][#"temp"]); // temp = 304.74
To get the main sub item in weather, which is an array with multiple items, you should point out its index to tell the selector which object in the array is the one you are looking for. In this case, it's 0:
NSLog(#"weather = %#", keys[#"weather"][0][#"main"]); // weather = Drizzle
I am a novice at IOS dev and i really need some help.
I want to parse (which is working) and fetch some JSON Data.
i used this tutorial for the http request and json parsing
http://www.mysamplecode.com/2013/04/ios-http-request-and-json-parsing.html
everything works fine with a 1 dimensional dictionary
but I need to be able to fetch the following JSON Data
[{"defaultGateway": "10.10.10.254", "hostname": "On", "connected": "true", "subnetMask": "255.255.255.255", "iPAddress": "10.10.10.10", "dhcpEnabled": "true"},
{"defaultGateway": "10.10.10.254", "hostname": "On", "connected": "true", "subnetMask": "255.255.255.255", "iPAddress": "10.10.10.10", "dhcpEnabled": "true"}]
after I use the following function I got the following dictionary which I really don't know how to access
NSDictionary * res = [NSJSONSerialization
JSONObjectWithData:data
options:NSJSONReadingMutableContainers
error:&error];
here is a picture of the dictionary
http://www11.pic-upload.de/09.11.14/5n4hdg3eh84q.png
How can I access for example the defaultGateway in the first dictionary?
You have a small logical error in your example. The expression [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error]; returns an NSArray and not and NSDictionary. So, first you should change this part to:
NSArray *result = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];
I know it's an array because your JSON string contains an array of two JSON objects. NSJSONSerialization will transform JSON arrays into objects of type NSArray and JSON objects into objects of type NSDictionary.
If you're not sure what your JSON contains, you can do the following:
id result = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];
if ([result isKindOfClass:[NSArray class]]){
// do something with the array
}
else if ([result isKindOfClass:[NSDictionary class]]){
// do something with the dictionary
}
As for your question, you can access the data in an NSDictionary by providing a key, which you can do in two ways:
NSString *gateway = [dictionary objectForKey:#"defaultGateway"];
or even faster:
NSString *gateway = dictionary[#"defaultGateway"];
Coming back to your example, to access the defaultGateway from the first of your two JSON objects, you can do the following:
NSArray *result = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error]; // parse the JSON and store in array
NSDictionary *dict = result[0]; // take the first of the two JSON objects and store it in a dictionary
NSString *gateway = dictionary[#"defaultGateway"]; // retrieve the defaultGateway property
As you might expect, i'm fairly new to obj-C, and i'm constantly trying to build knowledge and experience. But i'm still struggling with a lot of concepts, and that includes JSON data 'catching'.
I've seen many tutorials and guides but i just can't translate them into what i need. Most of the time they layout data in arrays or get multiple values, and (of course) use different variables, which makes everything confusing and unclear to me, even though this should be stupidly simple.
I'm trying to do something very simple :
Get a single value from the open weather API, the temperature.
I'll show you my code which, according to my disgraceful knowledge, should be perfect, but apparently it doesn't work :D
#implementation HomeViewController
{
NSMutableArray *tableData;
NSDictionary *jsonDict;
NSMutableString *title;
}
-(void) viewDidLoad
{
[super viewDidLoad];
NSError *error;
//I create my data array and the string i'll store my value later on
tableData = [[NSMutableArray alloc] init];
title = [[NSMutableString alloc]init];
// Creating the link for the json api so it fits coordinates ; this works but i edited the locations out to clear the code
NSString *s = [[NSString alloc]initWithFormat:#"http://api.openweathermap.org/data/2.5/weather?lat=%.05f&lon=%.05f", _annotation.coordinate.latitude, _annotation.coordinate.longitude];
// I go online and catch the data of the url stored in S
NSData *jSonData = [NSData dataWithContentsOfURL:[NSURL URLWithString:s]];
// This is a dictionary where all my data is stored from jsonData, keys and values all the way
jsonDict = [NSJSONSerialization JSONObjectWithData:jSonData options:NSJSONReadingMutableContainers error:&error];
// I use the string created previously and assign it the value stored in that dictionary, in the TEMP 'folder', right under MAIN.
title = [[jsonDict objectForKey:#"main"]objectForKey:#"main.temp"];
// I assign that title to a label so it appears in my view.
self.tempLabel.text = title;
...
}
There you go. I'm probably missing something very simple but i've been stuck on this and even if i feel I know what i'm doing, i'm probably missing something. So it'd be great if with the answer you give me, you could also tell me what I did wrong :D
Thank you very much for your support and knowledge. This community is amazing :)
Put a breakpoint after assigning value to jsonDict and use
po jsonDict
in the console to print out what you are getting. Then, adjust the code that extracts the value. And use modern Objective-C syntax for it.
Example
title = jsonDict[#"main"][#"temp"];
Note
po is a debugger command that will print out the contents of an object. If you need to print out the contents of a primitive, use p instead.
My guess is
jsonDict = [NSJSONSerialization JSONObjectWithData:jSonData options:NSJSONReadingMutableContainers error:&error];
is trying to create an nsdictionary, but it the results are coming back as an array. Try this:
NSError *e = nil;
NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: jsonDict options: NSJSONReadingMutableContainers error: &e];
if (!jsonArray) {
NSLog(#"Error parsing JSON: %#", e);
} else {
for(NSDictionary *item in jsonArray) {
NSLog(#"Item: %#", item);
}
}
This should set you right:
title = [[jsonDict objectForKey:#"main"]objectForKey:#"temp"];
To explain the issue, it seems you were referring to temp using a combination of dot syntax in the key.
EDIT: In response to your error:
That error appears when you're trying to find the length of a string on a value that is not of NSString type. Looks like temp is being returned as a number. So, to do what it looks like you're trying to do, you'll wanna convert [[jsonDict objectForKey:#"main"]objectForKey:#"temp"] to an NSString:
NSNumber *temp = [[jsonDict objectForKey:#"main"]objectForKey:#"temp"];
NSString *tempString = [temp stringValue];
OR
NSString *temp = [[[jsonDict objectForKey:#"main"]objectForKey:#"temp"] stringValue];
That will allow you to get the length: temp.length
**EDIT: Unless you're trying to get the length of the array of weather data...in which case i'd like to see more of that code
I come from Android dev, so sorry if I'm missing obvious iOS concepts here.
I have a JSON feed that looks like:
{"directory":[{"id":0,"fName":"...","lName":"...","title":"...","dept":"...","bld":"...","room":"...","email":"...","phone":"..."},{"id":1,"fName":"...","lName":"...","title":"...","dept":"...","bld":"...","room":"...","email":"...","phone":"..."}]}
Then, I have a Staff.h and .m with a class with properties to match it (id, fName, lName) ect.
I've been working at this for hours, but I can't seem to parse the JSON string to an array of Staff objects. The end goal is to get them into Core Data, so any advice would be nice.
Tutorials I've read haven't shown how to work with a JSON string in the form of {"directory":[{...}]} I had no problem doing this in my Android app, but I'm out of ideas here for iOS (6) in objective-c.
Thanks for reading.
You can do it like
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseObject options:0 error:&error];//response object is your response from server as NSData
if ([json isKindOfClass:[NSDictionary class]]){ //Added instrospection as suggested in comment.
NSArray *yourStaffDictionaryArray = json[#"directory"];
if ([yourStaffDictionaryArray isKindOfClass:[NSArray class]]){//Added instrospection as suggested in comment.
for (NSDictionary *dictionary in yourStaffDictionaryArray) {
Staff *staff = [[Staff alloc] init];
staff.id = [[dictionary objectForKey:#"id"] integerValue];
staff.fname = [dictionary objectForKey:#"fName"];
staff.lname = [dictionary objectForKey:#"lName"];
//Do this for all property
[yourArray addObject:staff];
}
}
}
Use: NSJSONSerialization
You use the NSJSONSerialization class to convert JSON to Foundation
objects and convert Foundation objects to JSON.
An object that may be converted to JSON must have the following properties:
The top level object is an NSArray or NSDictionary.
All objects are instances of NSString, NSNumber, NSArray, NSDictionary, or NSNull.
All dictionary keys are instances of NSString.
Numbers are not NaN or infinity.
You will get NSDictionary then you can parse (create) it to your object and then use it in CoreData.
Use following code:
NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
This will covert json data onto NSDictionary, which is similar to hashmap on android. I think this will help you. :)
you can use NSJSonSerialisation or AFNetworking library. Here is the example of AFNetworking to parse json response
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:#"http://example.com/resources.json" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"JSON: %#", responseObject);
NSDictionary *json = (NSDictionary *)responseObject;
NSArray *staffArray = json[#"directory"];
[staffArray enumerateObjectsUsingBlock:^(id obj, NSUInteger index, BOOL *stop){
Staff *staff = [[Staff alloc] init];
staff.id = [[obj objectForKey:#"id"] integerValue];
staff.fname = [obj objectForKey:#"fName"];
staff.lname = [obj objectForKey:#"lName"];
//add data to new array to store details
[detailsArray addObect:staff);
} ];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
}];
then use Core Data framework to store data.
I would take a look at RestKit. It provides object-mapping and CoreData backed storage.
For this, you can SBJSON framework.
You have to convert the response string into an NSDictionary like
NSString *responseString = [[NSString alloc]initWithData:responseData encoding:NSUTF8StringEncoding];
NSDictionary *dic = [responseString JSONValue];
Now you can create an object for Staff class.
Staff *staff = [[Staff alloc]init];
Then you can store values in this object like
staff.firstname = [[[dic objectForKey:#"directory"] objectAtIndex:0] objectForKey:#"fName"];
Now you can pass this single object to other classes
You can use the handmade solution proposed by #janak-nirmal, or use a library like jastor, https://github.com/elado/jastor, it doesn't make much difference.
I warn you against Restkit, because the ratio benefits-vs-pain is very low, in my opinion.
Moreover, it could be as use a tank to kill a fly in your scenario.