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:...
}