iOS SQLite与Android SQLite等效

Question

I am a new programmer in Objective-C. I have created an Android app and I've integrated SQLite. I want to build the same app in iOS. In Android for SQLite manipulation I've created a class that extends from Content Provider:

public class MyCProvider extends ContentProvider {
...
...
}

I've also overrided this methods: the boolean onCreate() method:

@Override
    public boolean onCreate() {
        dbHelper = new MySQLiteOpenHelper(getContext(), MySQLiteOpenHelper.DATABASE_NAME, null, MySQLiteOpenHelper.DATABASE_VERSION);
        return dbHelper != null;
    }



@Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
...
}



 @Override
        public String getType(Uri uri) {
...
}

@Override
    public Uri insert(Uri uri, ContentValues values) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        String nullColumnHack = null;

        long id = -1;
        Uri contentURI = null;

        switch (uriMatcher.match(uri)) {
            case GROUP_ALL_ROWS:
                contentURI = GROUP_CONTENT_URI;
                id = db.insert(USEFUL_NUMBER_GROUP_TABLE_NAME, nullColumnHack, values);
                break;
...
...
}

I wanted to know this methods equivalences in Objective- C. Any idea about this?

Answer 1

SQLite is provided directly with iOS and you'd just use its native C API . Apple doesn't provide any sort of wrapping.

The attitude seems to be that you can use SQLite directly or you can use Core Data, which is really quite a different thing — it's a queriable object graph which implicitly relies on an opaque storage method that can be a SQLite-based relational database if you like but Core Data is explicitly not a relational database. You can and should optimise for the SQL store underneath if that's the storage you pick but the database itself has a private schema and is not queried directly.

As such there's no equivalent to SQLiteOpenHelper . If you want to use SQLite then you need to do the work of opening, creating, migrating, etc for yourself.

iOS also doesn't have an equivalent to ContentProvider because that's a formalised model structure to allow sharing of data between applications but iOS doesn't really do sharing of data between applications in that sense. Applications from the same developer can share disk storage, all applications can open each other by URL schema, etc, but you can't write code that different applications can all interact with. So you'd just build whatever sort of model object you think most appropriate and its lifetime and interface would be whatever you explicitly decide.