How do I parse JSON with Objective-C? - objective-c

Question

I am new to iPhone. Can anyone tell me the steps to follow to parse this data and get the activity details, first name, and last name?
{
"#error": false,
"#data": {
"": {
"activity_id": "35336",
"user_id": "1",
"user_first_name": "Chandra Bhusan",
"user_last_name": "Pandey",
"time": "1300870420",
"activity_details": "Good\n",
"activity_type": "status_update",
"photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/sites/default/files/pictures/picture-1627435117.jpg"
},
"boolean": "1",
"1": {
"1": {
"photo_1_id": "9755"
},
"activity_id": "35294",
"album_name": "Kalai_new_Gallery",
"user_id": "31",
"album_id": "9754",
"user_first_name": "Kalaiyarasan",
"user_last_name": "Balu",
"0": {
"photo_0_id": "9756"
},
"time": "1300365758",
"activity_type": "photo_upload",
"photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/"
},
"3": {
"activity_id": "35289",
"user_id": "33",
"user_first_name": "Girija",
"user_last_name": "S",
"time": "1300279636",
"activity_details": "girija Again\n",
"activity_type": "status_update",
"photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/sites/default/files/pictures/picture-33-6361851323080768.jpg"
},
"2": {
"owner_first_name": "Girija",
"activity_id": "35290",
"activity_details": "a:2:{s:4:\"html\";s:51:\"!user_fullname and !friend_fullname are now friends\";s:4:\"type\";s:10:\"friend_add\";}",
"activity_type": "friend accept",
"owner_last_name": "S",
"time": "1300280400",
"photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/sites/default/files/pictures/picture-33-6361851323080768.jpg",
"owner_id": "33"
},
"4": {
"activity_id": "35288",
"user_id": "33",
"user_first_name": "Girija",
"user_last_name": "S",
"time": "1300279530",
"activity_details": "girija from mobile\n",
"activity_type": "status_update",
"photo_url": "http://184.73.155.44/hcl-meme/QA_TEST/sites/default/files/pictures/picture-33-6361851323080768.jpg"
}
}
}

Answer 1

With the perspective of the OS X v10.7 and iOS 5 launches, probably the first thing to recommend now is NSJSONSerialization, Apple's supplied JSON parser. Use third-party options only as a fallback if you find that class unavailable at runtime.
So, for example:
NSData *returnedData = ...JSON data, probably from a web request...
// probably check here that returnedData isn't nil; attempting
// NSJSONSerialization with nil data raises an exception, and who
// knows how your third-party library intends to react?
if(NSClassFromString(#"NSJSONSerialization"))
{
NSError *error = nil;
id object = [NSJSONSerialization
JSONObjectWithData:returnedData
options:0
error:&error];
if(error) { /* JSON was malformed, act appropriately here */ }
// the originating poster wants to deal with dictionaries;
// assuming you do too then something like this is the first
// validation step:
if([object isKindOfClass:[NSDictionary class]])
{
NSDictionary *results = object;
/* proceed with results as you like; the assignment to
an explicit NSDictionary * is artificial step to get
compile-time checking from here on down (and better autocompletion
when editing). You could have just made object an NSDictionary *
in the first place but stylistically you might prefer to keep
the question of type open until it's confirmed */
}
else
{
/* there's no guarantee that the outermost object in a JSON
packet will be a dictionary; if we get here then it wasn't,
so 'object' shouldn't be treated as an NSDictionary; probably
you need to report a suitable error condition */
}
}
else
{
// the user is using iOS 4; we'll need to use a third-party solution.
// If you don't intend to support iOS 4 then get rid of this entire
// conditional and just jump straight to
// NSError *error = nil;
// [NSJSONSerialization JSONObjectWithData:...
}

Answer 2

Don't reinvent the wheel. Use json-framework or something similar.
If you do decide to use json-framework, here's how you would parse a JSON string into an NSDictionary:
SBJsonParser* parser = [[[SBJsonParser alloc] init] autorelease];
// assuming jsonString is your JSON string...
NSDictionary* myDict = [parser objectWithString:jsonString];
// now you can grab data out of the dictionary using objectForKey or another dictionary method

Answer 3

NSString* path = [[NSBundle mainBundle] pathForResource:#"index" ofType:#"json"];
//将文件内容读取到字符串中，注意编码NSUTF8StringEncoding 防止乱码，
NSString* jsonString = [[NSString alloc] initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
//将字符串写到缓冲区。
NSData* jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *jsonError;
id allKeys = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONWritingPrettyPrinted error:&jsonError];
for (int i=0; i<[allKeys count]; i++) {
NSDictionary *arrayResult = [allKeys objectAtIndex:i];
NSLog(#"name=%#",[arrayResult objectForKey:#"storyboardName"]);
}
file:
[
{
"ID":1,
"idSort" : 0,
"deleted":0,
"storyboardName" : "MLMember",
"dispalyTitle" : "76.360779",
"rightLevel" : "10.010490",
"showTabBar" : 1,
"openWeb" : 0,
"webUrl":""
},
{
"ID":1,
"idSort" : 0,
"deleted":0,
"storyboardName" : "0.00",
"dispalyTitle" : "76.360779",
"rightLevel" : "10.010490",
"showTabBar" : 1,
"openWeb" : 0,
"webUrl":""
}
]

Answer 4

JSON parsing using NSJSONSerialization
NSString* path = [[NSBundle mainBundle] pathForResource:#"data" ofType:#"json"];
//Here you can take JSON string from your URL ,I am using json file
NSString* jsonString = [[NSString alloc] initWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
NSData* jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *jsonError;
NSArray *jsonDataArray = [NSJSONSerialization JSONObjectWithData:[jsonString dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&jsonError];
NSLog(#"jsonDataArray: %#",jsonDataArray);
NSDictionary *jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData options:kNilOptions error:&jsonError];
if(jsonObject !=nil){
// NSString *errorCode=[NSMutableString stringWithFormat:#"%#",[jsonObject objectForKey:#"response"]];
if(![[jsonObject objectForKey:#"#data"] isEqual:#""]){
NSMutableArray *array=[jsonObject objectForKey:#"#data"];
// NSLog(#"array: %#",array);
NSLog(#"array: %d",array.count);
int k = 0;
for(int z = 0; z<array.count;z++){
NSString *strfd = [NSString stringWithFormat:#"%d",k];
NSDictionary *dicr = jsonObject[#"#data"][strfd];
k=k+1;
// NSLog(#"dicr: %#",dicr);
NSLog(#"Firstname - Lastname : %# - %#",
[NSMutableString stringWithFormat:#"%#",[dicr objectForKey:#"user_first_name"]],
[NSMutableString stringWithFormat:#"%#",[dicr objectForKey:#"user_last_name"]]);
}
}
}
You can see the Console output as below :
Firstname - Lastname : Chandra Bhusan - Pandey
Firstname - Lastname : Kalaiyarasan - Balu
Firstname - Lastname : (null) - (null)
Firstname - Lastname : Girija - S
Firstname - Lastname : Girija - S
Firstname - Lastname : (null) - (null)

Answer 5

I recommend and use TouchJSON for parsing JSON.
To answer your comment to Alex. Here's quick code that should allow you to get the fields like activity_details, last_name, etc. from the json dictionary that is returned:
NSDictionary *userinfo=[jsondic valueforKey:#"#data"];
NSDictionary *user;
NSInteger i = 0;
NSString *skey;
if(userinfo != nil){
for( i = 0; i < [userinfo count]; i++ ) {
if(i)
skey = [NSString stringWithFormat:#"%d",i];
else
skey = #"";
user = [userinfo objectForKey:skey];
NSLog(#"activity_details:%#",[user objectForKey:#"activity_details"]);
NSLog(#"last_name:%#",[user objectForKey:#"last_name"]);
NSLog(#"first_name:%#",[user objectForKey:#"first_name"]);
NSLog(#"photo_url:%#",[user objectForKey:#"photo_url"]);
}
}