如何编写 SQLite3 Objective-C 结果集包装器？

Question

I want to write an SQLite resultset wrapper class for iPhone to dynamically call sqlite3_column_int or sqlite3_column_text . In my fetchAll method I would like without knowing data type to just return the data.

I was thinking of using performSelector . How would I design such a class to interact with SQLite?

Answer 1

No, you can't use an Objective-C feature to call a C function in that way (performSelector that is). You can call C code within objective-C. One approach may be to keep function pointers to the C functions you want to call, then implement some logic to choose the appropriate function pointer to reference.

Answer 2

I'm not quite sure I understand, but I suppose you might be able to write a few Objective-C methods containing small amounts of pure C and call performSelector on those. Unfortunately the SQLite3 API for the iPhone kind of sucks.

Answer 3

You could take a look at how other wrappers do it. For example, here's the source of the resultset object from Flying Meat Database: http://code.google.com/p/flycode/source/browse/trunk/fmdb/src/FMResultSet.h http://code.google.com/p/flycode/source/browse/trunk/fmdb/src/FMResultSet.m