Programming iOS 4

SQLite

SQLite (http://www.sqlite.org/docs.html) is a lightweight, full-featured relational database that you can talk to using SQL, the universal language of databases. This can be an appropriate storage format when your data comes in rows and columns (records and fields) and needs to be rapidly searchable.

In the same way as you can link to libxml2.dylib, you can link to libsqlite3.dylib (and import <sqlite3.h>) to access the power of SQLite. As with libxml2, talking C to sqlite3 may prove annoying. There are a number of lightweight Objective-C front ends. In this example, I use fmdb (https://github.com/ccgus/fmdb) to read the names of people out of a previously created database:

NSString* docsdir = [NSSearchPathForDirectoriesInDomains(
    NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString* dbpath = [docsdir stringByAppendingPathComponent:@"people.db"];
FMDatabase* db = [FMDatabase databaseWithPath:dbpath];
if (![db open]) {
    NSLog(@"Ooops");
    return;
}
FMResultSet *rs = [db executeQuery:@"select * from people"];
while ([rs next]) {
    NSLog(@"%@ %@",
        [rs stringForColumn:@"firstname"],
        [rs stringForColumn:@"lastname"]);
}
[db close];
/* output:
Matt Neuburg
Snidely Whiplash
Dudley Doright
*/

You can include a previously constructed SQLite file in your app bundle, but you can’t write to it there; the solution is to copy it from your app bundle into another location, such as the Documents directory, before you start working with it.

The Core Data framework also uses SQLite as ...