connect to sqlite - objective-c

Question

I'm having some issue connecting to my sqlite database.. I'm using xcode version 4.4.1
here's my code..
NSString *docsDir;
NSArray *dirPaths;
// Get the documents directory
dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];
// Build the path to the database file
databasePath = [[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent: #"signature.db"]];
NSFileManager *filemgr = [NSFileManager defaultManager];
if ([filemgr fileExistsAtPath: databasePath ] == NO)
{
const char *dbpath = [databasePath UTF8String];
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
status.text = #"Connected..";
} else {
status.text = #"Failed to open/create database..";
}
}
[filemgr release];
Any suggestion..?
Thanks,
Boom

Answer 1

There is no need to check if the database exists; sqlite3_open_v2() (reference) will create the database, if it does not exist, if you pass the flag SQLITE_OPEN_CREATE:
NSString *dbPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPath:#"signature.db"];
if (sqlite3_open_v2([dbPath UTF8String], &database, SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE) == SQLITE_OK)
{
status.text = #"Connected..";
// Check the schema and install if it doesn't exist
sqlite3_close(database);
} else {
status.text = #"Failed to open/create database..";
}

Answer 2

You may wish to check if the DB file is in place if you have one in your app's bundle that is pre-built so you can drop it into your documents folder. Of course, as you enhance your app, any schema changes will need to be done in code. Here is some code that I use (that works, but needs to updated a bit)
When opening/creating the DB I use this to specify where the DB file will be. I don't put it with the init because my location is different between iOS and Mac OS X and I want the DB code to work with both:
NSString *dbFilePath;
NSArray *searchPaths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentFolderPath = searchPaths[0];
dbFilePath = [documentFolderPath stringByAppendingPathComponent: #"MyDBFile.db"];
MyDB* appDB = [[EasySpendLogDB alloc] initWithFile:dbFilePath];
if(!appDB) {
// show error
return;
}
This is in my DB access class. It uses some wrapper classes I wrote:
- (id) initWithFile: (NSString*) filePathName {
if(!(self = [super init])) return nil;
BOOL myPathIsDir;
BOOL fileExists = [[NSFileManager defaultManager]
fileExistsAtPath: filePathName
isDirectory: &myPathIsDir];
NSString *backupDbPath = [[NSBundle mainBundle]
pathForResource:#"MyDBFile"
ofType:#"db"];
if (backupDbPath != nil && !fileExists) {
[[NSFileManager defaultManager]
copyItemAtPath:backupDbPath
toPath:filePathName
error:nil];
}
db = [[ABSQLiteDB alloc] init];
if(![db connect:filePathName]) {
return nil;
}
[self checkSchema]; // this is where schema updates are done (see project sample)
return self;
}
You may also want to check out this objective-c wrapper I wrote that has a sample project: https://github.com/AaronBratcher/ABSQLite