Question

is posible using JSON-Framework for Iphone to know if a tag exists inside the JSON like in JAVA with the function hasTag(String)?

Answer 1

If by tag you mean name/key and you’re using SBJSON, use -objectForKey: and test if the return value is nil. For instance, if person is an NSDictionary instance returned by the JSON parser and it can optionally contain a nickname,

if ([person objectForKey:@"nickname"] != nil)
{
    // `nickname' is available; do something with it
}