NSInvalidArgumentException... how do I define the arguments correctly? - objective-c

Question

I'm getting this exception on the following code. I think it's because I have not defined the two incoming parameter types. They are local; so how do I define them (and where).
Error: 2011-04-27 11:18:03.226
PointPeek[174:707] * Terminating app
due to uncaught exception
'NSInvalidArgumentException', reason:
'+[SQLiteDB addRecordToDatabase::]:
unrecognized selector sent to class
0x1fe70'
Here's the calling line of code:
[SQLiteDB addRecordToDatabase:
symbol.data: symbol.typeName];
and here's the method I'm calling:
- (void) addRecordToDatabase:data: typeName {
NSString *insertCommand = [NSString stringWithFormat:#"INSERT INTO CardData (CARD_ID, CARD_NAME, CODE_VAL) VALUES ('/%#', '/%#', '/%#')", data, #"Test Card", typeName];
if(sqlite3_open_v2(cDatabasePath, &db, SQLITE_OPEN_READWRITE, NULL) == SQLITE_OK) {
}

Answer 1

Error: 2011-04-27 11:18:03.226
PointPeek[174:707] * Terminating app
due to uncaught exception
'NSInvalidArgumentException', reason:
'+[SQLiteDB addRecordToDatabase::]:
unrecognized selector sent to class
0x1fe70'
Basically, the "unrecognized selector sent to..." message means you tried to tell an object (or class) to do something it doesn't know how to do. ("selector" is another name for method).
You defined your method of the SQLiteDB class as an instance method:
- (void) addRecordToDatabase:data: typeName;
We know that because of the - in the method name (see Methods and Messaging and Class Interface). In the error message you got, notice that it began with a +, which means you attempted to call a method on the SQLiteDB class itself, rather than on an instance of that class.
In other words, you attempted to do this:
[SQLiteDB addRecordToDatabase: symbol.data: symbol.typeName];
when you needed to do something like this:
SQLiteDB *db = [[[SQLiteDB alloc] init] autorelease]; // an instance
[db addRecordToDatabase: symbol.data: symbol.typeName];
(Note that the previous 2 lines of code aren't all that useful in and of themselves. Presumably, instead of creating an instance of SQLiteDB in this method, you'd have it as an instance variable).

Answer 2

[SQLiteDB addRecordToDatabase: symbol.data: symbol.typeName];
That'd assume that addRecordToDabase:: is a class method, not an instance method.
Furthermore, that is an awful name for a method. Try something like:
- (void)addRecordWithData:(NSData*)aData andType:(NSString*)aType;
That is, bare :s are to be avoided and you should always specify the type of the parameter (and not fall back to id as you did here).
Finally, why aren't you using Core Data or, at the very least, FMDB? Raw SQLite is a waste of time.
SQLite is harder to write code for than Core Data, most likely. If you are a newbie to both, Core Data is a better return on investment of your time.
In any case, the questions in your comment indicate that you really need to start by understanding Objective-C. Apple provides an excellent language guide.