Creating NSDictionary - ios

Question

how i can create Dictionary that when i create jsondata with it, json looks like :
"historyStep":[
{
"counter": "50",
"timestamp": "1461674383632"
}
]
I did this :
NSMutableDictionary*jsonDictOth = [[NSMutableDictionary alloc]init];
[jsonDictOth setObject:#(810) forKey:#"counter"];
[jsonDictOth setObject:#"1464957395241.447998" forKey:#"timestamp"];
NSMutableDictionary *jsonDictMain = [[NSMutableDictionary alloc]initWithObjectsAndKeys:jsonDictOth,#"historyStep", nil];
NSError*error;
NSData *data = [NSJSONSerialization dataWithJSONObject:jsonDictMain
options:NSJSONWritingPrettyPrinted
error:&error];
but it looks :
historyStep = {
counter = 810;
timestamp = "1464957395241.447998";
};

Answer 1

You are missing a level: NSDictionary (top level) with NSArray of NSDictionary in the top level key historyStep:
NSMutableDictionary *topLevel = [[NSMutableDictionary alloc] init];
NSArray *historySteps = [[NSMutableArray alloc] init];
//Here you may have a for loop in case there are more steps
NSDictionary *aStep = #{#"counter":#"50", #"timestamp":#"1461674383632"};
[historySteps addObject:aStep]
[topLevel setObject:historySteps forKey#"historyStep"];
NSError*error;
NSData *data = [NSJSONSerialization dataWithJSONObject:topLevel
options:NSJSONWritingPrettyPrinted
error:&error];

Answer 2

NSDictionary *innerDictionary = [[NSDictionary alloc]initWithObjectsAndKeys:#"50", #"counter",#"1461674383632", #"timestamp", nil];
NSArray *array = [[NSArray alloc]initWithObjects:innerDictionary, nil];
NSDictionary *outerDict = [[NSDictionary alloc]initWithObjectsAndKeys:array, #"historyStep", nil];
Use this code it will work perfectly.

Answer 3

Your code should be like,
NSMutableDictionary*jsonDictOth = [[NSMutableDictionary alloc]init];
[jsonDictOth setObject:#(810) forKey:#"counter"];
[jsonDictOth setObject:#"1464957395241.447998" forKey:#"timestamp"];
NSMutableArray *arr = [[NSMutableArray alloc]init];
[arr addObject:jsonDictOth];
NSMutableDictionary *jsonDictMain = [[NSMutableDictionary alloc]initWithObjectsAndKeys:arr,#"historyStep", nil];
NSLog(#"jsonMain is %#",jsonDictMain);
NSError*error;
NSData *data = [NSJSONSerialization dataWithJSONObject:jsonDictMain
options:0
error:&error];
It's output is,
jsonMain is {
historyStep = (
{
counter = 810;
timestamp = "1464957395241.447998";
}
);
}
You just missed one array between