如何将NSDictionary转换为包含NSDictionary的json的NSString?

Dam*_*mir 2 ios ios6

如何转换NSDictionaryNSString其中包含JSONNSDictionary?我试过但没有成功

//parameters is NSDictionary
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:parameters
                                                       options:0
                                                         error:&error];
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nsg*_*ver 5

如果jsonData是 NSDictionary

NSString *str=[NSString stringWithFormat:@"json data is %@", jsonData];
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或者如果jsonData是 NSData

NSString *str = [[NSString alloc] initWithData:jsonData encoding:NSASCIIStringEncoding];
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