Ios 将UIImage另存为Blob SQLite

我有以下代码将信息推送到数据库。它提供了一个成功的插入，但是包含图像blob的canvas列为NULL。根据我在StackOverflow上看到的其他答案，我对sqlite3_prepare_v2和sqlite3_bind_blob的使用进行了建模

-(void) sendMoment: (Album *) alb moment:(Moment *) m
{
    @try {
        NSFileManager *fileMgr = [NSFileManager defaultManager];

        // First, test for existence of writable file:
        NSError *error;
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"pictures.sqlite"];

        BOOL success = [fileMgr fileExistsAtPath:writableDBPath];
        if (!success){
            // The writable database does not exist, so copy the default to the appropriate location.
            NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"pictures.sqlite"];
            success = [fileMgr copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
            if (!success) {
                NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
            }
        }

        NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
        [dateFormat setDateFormat:@"yyy-MM-dd HH:mm:ss"];
        NSString *dateString = [dateFormat stringFromDate: m.timestamp];

        //add passed-in moment to the given album
        sqlite3_stmt *sqlStatement;
        NSData *imageData = UIImageJPEGRepresentation([m.moment firstObject], 1.0);


        NSString *deleteSQL = [NSString stringWithFormat:@"DELETE FROM MomentTbl WHERE user = \"t-amkruz\""];

        NSString *momentInsertSQL = [NSString stringWithFormat:@"INSERT INTO MomentTbl (momentID, albumID, title, timestamp, author, latitude, longitude, canvas) VALUES (NULL, %d, '%@', '%@', '%@', '%@', '%@', ?)", alb.ID, alb.title, dateString, @"user", m.latitude, m.longitude];
        const char *query_stmt = [momentInsertSQL UTF8String];
        const char *dbPath = [writableDBPath UTF8String];

        int result = sqlite3_open(dbPath, &db);

        if (SQLITE_OK == result) {
            char *errInfo = nil;

            sqlite3_prepare_v2(db, query_stmt, -1, &sqlStatement, NULL);

            sqlite3_bind_blob(sqlStatement, 1, [imageData bytes], [imageData length], SQLITE_TRANSIENT);

            result = sqlite3_exec(db, query_stmt, nil, nil, &errInfo);
            if (SQLITE_OK == result) {
                NSLog(@"Sucessful insert");
            } else {
                NSLog(@"Insert failed");
            }
            sqlite3_close(db);
        }

        else {
            NSLog(@"Could not open database");
        }

    }
    @catch (NSException *exception) {
        NSLog(@"An exception occured: %@", [exception reason]);
    }
}

---

同样，我唯一有问题的部分是最后一列；每隔一列正确插入一个值。我已经验证了imageData是非零的。当我使用NSLog检查prepare_v2语句和bind_blob语句时，它们都返回0。我真的很感激你的帮助

结果表明，我需要用以下语句替换exec语句和后续if语句：

if(sqlite3_step(sqlStatement) == SQLITE_OK){
    NSLog(@"Sucessful insert");
}
else {
    NSLog(@"Insert failed");
}

希望这对其他人有帮助