Friday, March 14, 2014

Sprite Kit: Animation in English-Speak

Message sequence of actions to SKAction, then message that sequence of actions to repeatActionForever, then run that forever action to the player (SKSpriteNode)

Thursday, March 13, 2014

Sprite Kit: Up is down, down is up

There's no error on messaging the location.x to moveToX action of SKAction, think spaceship which just move left and right and remains stationary on its Y

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
    UITouch* touched = [touches anyObject];

    CGPoint location = [touched locationInView:self.view];

    SKAction* moveAction = [SKAction moveToX: location.x duration:0.0];
    [player runAction: moveAction];

However, it's preferable to use locationInNode. If we want the spaceship to move in all direction yet we use locationInView, the app will exhibit this same error:

CGPoint location = [touched locationInView:self.view]
SKAction* moveAction = [SKAction moveTo: location duration:0.0];    

Though the spaceship's X will move accordingly to your touch, the spaceship's Y will not follow your finger movements.

To rectify that flaw, get the location from SKScene's view (self) instead of the UIView's view (self.view), then message that view to touched object's locationInNode instead of locationInView

CGPoint location = [touched locationInNode:self];
SKAction* moveAction = [SKAction moveTo: location duration:0.0];

Happy Coding! ツ

Wednesday, March 12, 2014

Sprite Kit: Determine touch location in English-speak

Create a touchesMoved event in the game scene. To determine the touched location, first get a UITouch from touched object (use anyObject), then from that UITouch object get its location(CGPoint) in view, with the parameter being the game scene's view.

To move an object (e.g. player (SKSpriteNode)), message the location(CGPoint) to the moving action functionality (moveTo) of an action(SKAction). Then message that action to the player's (SKSpriteNode) run action functionality

Tuesday, March 11, 2014

Making sense of Sprite Kit and iOS's MVC

Sprite Kit flow in English-speak

From the ViewController’s viewDidLoad we configure the view by doing the following:

1. Create a game view by casting the ViewController’s view to SKView

    SKView has some properties like:

         showsFPS, showsNodeCount, showsDrawCount

2. We create game scene via instance of a class that derives from SKScene

3. Then we call game view’s presentScene to present the game scene

A game scene extends SKScene. On game scene’s initialization: 

1. We can set the size of the scene, from the scene we can also set the background color. 

2. We can add a player (instance of SKSpriteNode) on game scene by calling the game scene’s addChild which has a parameter of SKSpriteNode

Friday, February 28, 2014


Can we survive the onslaught of frameworks that makes our job easier and could potentially make our jobs obsolete?

First, there's No Software, then there's NoSQL, now No Programming is needed when making an application. Ok I exaggerated a bit, in this stage of technology we can now learn to make applications with almost no programming background required.

You got a complete list (no paging) of data a user wanted to filter, it would be overkill to re-fetch the data from the server as all the data being used on filtering are already at the client-side. We can use some jQuery skills or some good ol' DOM manipulation skills to do that task. But who would do that when the No technologies are all the rage now?

Here's one of the many ways to do no programming with AngularJS, enjoy! Active filtering:

Programming required to fit the filter requirement of clicking the search button first: almost no programming required

Thursday, February 13, 2014

Sparrow Framework newbie: Run is not available on project

Run is not available on Scaffold project:

Switch to Scaffold project:

When DEFAULT doesn't default

I almost gave a wrong code review to a colleague:

It's better to use NOT NULL:

ALTER TABLE dbo.blah
ADD IsTransferred BIT NULL DEFAULT (0);

Is there a business or technical reason why IsTransferred should be nullable?

On the above DDL for IsTransferred, nullable or not nullable, IsTransferred defaults to 0, hence this is a superfluous code:

-- initialize new column, i.e., NULL columns, to "not transferred"
UPDATE dbo.blah
SET IsTransferred = 0
WHERE IsTransferred IS NULL ;

Further read:

The code could be shortened and optimized but I'm not inclined to advise it; this query is just a one-time thing, no need to micro-optimize. The code is good enough

Spotted the wrong thing on the above advice? The above advice is correct if we are using PostgreSQL. However we are using SQL Server, the newly-added IsTransferred field will default to null if the field is nullable regardless of the above DDL indicating a default value of false(0).

So the UPDATE above is not a superfluous code, at least on SQL Server, the UPDATE is still needed despite the DEFAULT 0 clause. PostgreSQL (and other RDBMSes for that matter) is intuitive in this regard, it honors the DEFAULT clause regardless of the field is nullable or not.

Further read:

PostgreSQL-related news:

Happy Coding! ツ