Retrieve nsdata from sqlite stored in Blob data type for iPhone App

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);

来源：https://stackoverflow.com/questions/4724118/retrieve-nsdata-from-sqlite-stored-in-blob-data-type-for-iphone-app