I always hear people described as being a back-end guy or a front-end guy. Really, I think those terms are a little ambiguous and can be a little misleading. Or worse, you can get pigeon-holed into one or the other and then people don't trust you with half of the system.

I have been working on a few sprints lately that require some javascript to do dynamic positioning of a DOM element on whatever was just clicked on the screen. Here is a sample of some of that code. It assumes that there is an element, a.some_link, that when you click it the dynamically positioned element, #DP, places itself just to the right and centered vertically. It will also detect if positioning to the right will cause it to be off the screen and flip it to the left side instead. The only CSS requirement is that #DP be "position: absolute;". [js]$("a.some_link").click(function() { //Get the coordinates of the clicked element. var cellPosition = $(this).position(); //Add the left displacement to the width of the trigger, //placing the DP just to the right of it. var horizontalPosition = cellPosition.left + $(this).outerWidth(); //Here is the fancy part. If the position plus the width of your DP //if greater than the window width, change the position to the left //side of the trigger. if (horizontalPosition + $("#DP").outerWidth() > $(window).width()) { horizontalPosition = cellPosition.left - $("#DP").outerWidth(); } //Center your DP vertically on the trigger. var verticalPosition = cellPosition.top - ($("#DP").outerHeight() / 2) + ($(this).outerHeight() / 2); //Update the position of your DP. $("#DP").css({top: verticalPosition, left: horizontalPosition}); });[/js] Also note that if you were to call "animate" instead of "css" in that last call, then it would animate the movement instead of just snapping it to the new position.

Using a sqlite database in an iPhone app is actually really easy. The only real requirement to get started is that you need to create a sqlite database to include, which is very easy to do.

sqlite3 test.sqlite3

CREATE TABLE iphone_test ( id INTEGER PRIMARY KEY, value VARCHAR(255) );

INSERT INTO iphone_test (value) VALUES ("This is value 1"); INSERT INTO iphone_test (value) VALUES ("This is value 2");

You need to link the sqlite3 framework library to your project. All you need to do is right-click on the Frameworks folder and select Add > Existing Frameworks... then select:

/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS2.2.1.sdk/usr/lib/libsqlite3.0.dylib

Step 3 - Add Some Code to Your AppDelegate.h

Open up your AppDelegate.h and add an import for sqlite3.h so you can use sqlite. Then this declaration inside your @interface so you have a nice handle to the database:

sqlite3 *database;

Then add these prototypes for the methods we are adding to the AppDelegate.m:

- (void)verifyDatabase:(NSString *)databaseName databasePath:(NSString *)databasePath;

- (NSString *) randomRecordContent;

Step 4 - Add Some Code to Your AppDelegate.m

Open up your appDelegate.m and add this method in somewhere. This will make sure that the database file exists in the user's file store and if it doesn't, it will copy it over from your application code.

- (void)verifyDatabase:(NSString *)databaseName databasePath:(NSString *)databasePath { NSFileManager *fileManager = [NSFileManager defaultManager]; if (![filemanager fileExistsAtPath:databasePath]) { NSString *databasePathFromApp = [[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:databaseName]; [fileManager copyItemAtPath:databasePathFromApp toPath:databasePath error:nil]; } [fileManager release]; }

Then add this code inside your applicationDidFinishLaunching method to get the location of the database in the users phone:

NSString *databaseName = @"test.sqlite3"; NSString *documentsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex: 0]; NSString *documentsPath = [documentsDir stringByAppendingPathComponent:databaseName];

Now call the verifyDatabase method to copy the database from your app code to the users file store in case it isn't already there.

[self verifyDatabase: databaseName databasePath:databasePath];

Open the database so you can use it throughout your application:

sqlite3_open([databasePath UTF8String], &database);

Don't forget to close the connection in your dealloc method:

sqlite3_close(database);

Finally, add in a method that will read something from the database. In this case, we are adding the implementation of randomRecordContent that we specified in the header.

-(NSString *) randomRecordContent { NSString *theValue; const char *sqlStatement = "select value from iphone_test order by random() limit 1"; sqlite3_stmt *compiledStatement; if (sqlite3__prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { while (sqlite3_step(compiledStatement) == SQLITE_ROW) { theValue = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)]; } } sqlite3_finalize(compiledStatement); return theValue; }

Now you are all set. As long as you have a handle to your AppDelegate, you can call this method and grab something from the database. For example, if you are in your view controller you can get a handle and call the method like this:

YourAppDelegate yourAppDelegate = (YourAppDelegate *)[[UIApplication sharedApplication] delegate]; NSString theValue = [yourAppDelegate randomRecordContent];

So there you have it. Hopefully that code is pretty readable. Please post comments or e-mail me if you have any questions.