Retrieve nsdata from sqlite stored in Blob data ty

问题:

In iPhone App how to store UIImage converted into NSData to sqlite table in BLOB datatype? Is there any kind of binding needed(NSData ->Blob)?

or

While retrieving image stored in NSData form in sqlite Blob datatype, should I need to perform any task to convert that stored database in blob datatype to get back into NSData form?

Please help and suggest.

回答1:

I used something like this:

// prepare sqlite3 statement before this line
int res = sqlite3_step(stmt);
if (res == SQLITE_ROW) {
    const void *ptr = sqlite3_column_blob(stmt, 0);
    int size = sqlite3_column_bytes(stmt, 0);
    data = [[NSData alloc] initWithBytes:ptr length:size];
    sqlite3_reset(stmt);

    return [data autorelease];
} 
sqlite3_reset(stmt);

For saving as blob you can extract pointer and size of NSData using [data bytes] and [data length]. And then bind to your BLOB row

sqlite3_bind_blob (stmt, 2, [data bytes], [data length], SQLITE_TRANSIENT);