详解Sqlite如何在IOS开发中应用

- (BOOL) initializeDb {  
NSLog (@"initializeDB");  
// look to see if DB is in known location (~/Documents/$DATABASE_FILE_NAME)  
//START:code.DatabaseShoppingList.findDocumentsDirectory  
NSArray *searchPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);  
NSString *documentFolderPath = [searchPaths objectAtIndex: 0];  
//查看文件目录  
NSLog(@"%@",documentFolderPath);  
dbFilePath = [documentFolderPath stringByAppendingPathComponent:@"shopping.db"];  
//END:code.DatabaseShoppingList.findDocumentsDirectory  
[dbFilePath retain];  
//START:code.DatabaseShoppingList.copyDatabaseFileToDocuments  
if (! [[NSFileManager defaultManager] fileExistsAtPath: dbFilePath]) {  
// didn't find db, need to copy  
NSString *backupDbPath = [[NSBundle mainBundle] pathForResource:@"shopping" ofType:@"db"];  
if (backupDbPath == nil) {  
// couldn't find backup db to copy, bail  
return NO;  
} else {  
BOOL copiedBackupDb = [[NSFileManager defaultManager] copyItemAtPath:backupDbPath toPath:dbFilePath error:nil];  
if (! copiedBackupDb) {  
// copying backup db failed, bail  
return NO;  
}  
}  
}  
return YES;  
//END:code.DatabaseShoppingList.copyDatabaseFileToDocuments  
NSLog (@"bottom of initializeDb");  
}  
- (void)applicationDidFinishLaunching:(UIApplication *)application {  
// copy the database from the bundle if necessary  
if (! [self initializeDb]) {  
// TODO: alert the user!  
NSLog (@"couldn't init db");  
return;  
}  
    // Add the tab bar controller's current view as a subview of the window  
    [window addSubview:tabBarController.view];  
} 
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