Create a JsonString in iOS - iphone

Question

I am new in iOS. I created a JSON NSDictionary like this:
NSArray *keys = [NSArray arrayWithObjects:#"User", #"Password", nil];
NSArray *objects = [NSArray arrayWithObjects:#"Ali", #"2020", nil];
NSDictionary *jsonDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
And then I could convert it to NSString via two mechanisms:
1)
NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonDictionary options:0 error:&error];
NSString *jsonString = nil;
if (! jsonData) {
NSLog(#"Got an error: %#", error);
} else {
jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
}
2)
NSString *jsonString = [jsonDictionary JSONRepresentation];
In the second way I get this warning :
Instance method '-JSONRepresentation' not found (return type defaults to 'id')
But when I run the project, both of the mechanisms works fine:
NSLog(#"Val of json parse obj is %#",jsonString);
Do you know how can I remove the warning in the second way?
My main goal is POST this json String to an external database using RESTful Web Service.
Basically which way is better considering my main goal?

Answer 1

You should use NSJSONSerialization as it is faster and comes directly with iOS SDK as long as your "target audience" is iOS5+
To POST the data to your web service you need the create a request along these lines...
NSDictionary * postDictionary = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"value1", #"value2", nil]
forKeys:[NSArray arrayWithObjects:#"key1", #"key2", nil]];
NSError * error = nil;
NSData * jsonData = [NSJSONSerialization dataWithJSONObject:postDictionary options:NSJSONReadingMutableContainers error:&error];
NSMutableURLRequest * urlRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:#"your_webservice_post_url"]];
[urlRequest setValue:#"application/json" forHTTPHeaderField:#"Accept"];
[urlRequest setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[urlRequest setHTTPMethod:#"POST"];
[urlRequest setHTTPBody:jsonData];
NSURLConnection * myConnection = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self startImmediately:YES];
Please read up on NSURLConnectionDelegate protocol.

Answer 2

For iOS 5.0 > :
Use NSJSONSerialization like this :
NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:NSJSONWritingPrettyPrinted error:&error];
NSString *resultAsString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
NSLog(#"jsonData as string:\n%# Error:%#", resultAsString,error);
For < iOS 5 :
Use json-framework a third party library that uses category for NSDictionary to provide json string :
NSString *jsonString = [dictionary JSONRepresentation];
//with options
NSString *jsonString = [dictionary JSONStringWithOptions:JKSerializeOptionNone error:nil]

Answer 3

This will help you... Convert NSDictionary to JSON with SBJson

Answer 4

use this way i hope it will help you
NSArray *keys = [NSArray arrayWithObjects:#"User", #"Password", nil];
NSArray *objects = [NSArray arrayWithObjects:#"Ali", #"2020", nil];
NSDictionary *jsonDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
NSError *error = nil;
// NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonDictionary options:0 error:&error];
id result = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&error];
NSLog(#"\n\n\n id for json==%# \n\n\n\n\n",result);

Answer 5

JSON DEFAULT METHOD......
+(NSDictionary *)stringWithUrl:(NSURL *)url postData:(NSData *)postData httpMethod:(NSString *)method {
NSDictionary *returnResponse=[[NSDictionary alloc]init];
#try {
NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:180]; [urlRequest setHTTPMethod:method];
if(postData != nil)
{
[urlRequest setHTTPBody:postData];
}
[urlRequest setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[urlRequest setValue:#"application/json" forHTTPHeaderField:#"Accept"];
[urlRequest setValue:#"text/html" forHTTPHeaderField:#"Accept"];
NSData *urlData;
NSURLResponse *response;
NSError *error;
urlData = [NSURLConnection sendSynchronousRequest:urlRequest
returningResponse:&response
error:&error];
returnResponse = [NSJSONSerialization
JSONObjectWithData:urlData
options:kNilOptions
error:&error];
} #catch (NSException *exception) { returnResponse=nil; } #finally { return returnResponse; } }
Return Method :
+(NSDictionary )methodName:(NSString)string {
NSDictionary *returnResponse; NSData *postData = [NSData dataWithBytes:[string UTF8String] length:[string length]]; NSString *urlString = #"https//:..url...."; returnResponse=[self stringWithUrl:[NSURL URLWithString:urlString] postData:postData httpMethod:#"POST"];
return returnResponse;
}