Emanuele Feronato

italian geek and PROgrammer

Talking about Game development, Html, iOS and Javascript.

Some days ago I showed you the basics of an HTML game optimized for the iPhone.

Now we are going to improve the game with three exciting new features:

* Showing a splash/preloader screen
* Changing iPhone top bar appearance
* Saving data locally

To show a preloader we just need to add a line in the header of the page:

This will work only on iOS 3.0 and later, and splash.png (which you will change with any other path) is the splash image that is displayed while your web application launches, replacing the default screenshot of the web application taken the last time it was used.

Your image must have a size of 320×460 pixels.

In the following picture, on the left the picture I used, on the right how it is shown on the iPhone.

You can also change the status bar with just one line in the header:

This will work only if your app is launched in full screen mode (refer to step 1 to see how to launch a web app in full screen mode).

content attribute may have three values:

default: displays the status bar as you are used to see.

black: the status bar will have a black background.

black-translucent: the status bar is black and translucent. In this case, the web content is displayed even below the status bar, partially obscured by the status bar.

This is how my app looks before and after changing the status bar:

As you can see, the status bar is black.

To save data locally, localStorage comes into our help as it acts like a browser local database, or something like a cookie, if you prefer.

That’s why in this script:

$(document).ready(function(){
	var currentNumber = Math.floor(Math.random()*10);
	var score = 0;
	if(localStorage.topScore==undefined){
		localStorage.topScore=0;	
	}
	$("#topscore").html("Top score: "+localStorage.topScore);
	$("#number").html(currentNumber);
	$("#comment").html("Click higher or lower");
	$("#higher").live("click tap",(function(){
		var newNumber = Math.floor(Math.random()*10);
		if(newNumber >= currentNumber){
			score++;	
			if(score>localStorage.topScore){
				localStorage.topScore=score;
				$("#topscore").html("Top score: "+localStorage.topScore);
			}
			$("#comment").html("Good! score: "+score);	
		}
		else{
			$("#comment").html("Bad! score: "+score);
		}
		currentNumber = newNumber;
		$("#number").html(currentNumber);	
	}));
	$("#lower").live("click tap",(function(){
		var newNumber = Math.floor(Math.random()*10);
		if(newNumber <= currentNumber){
			score++;	
			if(score>localStorage.topScore){
				localStorage.topScore=score;
				$("#topscore").html("Top score: "+localStorage.topScore);
			}
			$("#comment").html("Good! score: "+score);	
		}	
		else{
			$("#comment").html("Bad! score: "+score);
		}
		currentNumber = newNumber;
		$("#number").html(currentNumber);
	}))
});

At lines 4-7, 14-17 and 30-33 we are using a variable called topScore saved into localStorage accessing it just like an ordinary variable.

And that’s enough for this step, no we have everything we need to create a complete game with high scores, which will be shown during next step.