Developers should iPhone-optimize their sites

A while ago I wrote how the Dejal site is iPhone-optimized: when you view it on an iPhone or iPod touch, the website content is reformatted to fit neatly in the 320-pixel-wide display:

I would suggest that any developers who write iPhone software should do this too. So here's some technical info on what I did. This isn't necessarily the best solution, but it works for me, and isn't very difficult.

Firstly, of course, you need to be able to detect whether you're running on an iPhone or elsewhere. The standard way to do this is by looking at the "user agent" value of the HTTP session. In PHP, you can simply look at the $_SERVER['HTTP_USER_AGENT'] global variable. I have the following function in a utility PHP file included on every page (via the header code):

    function getIsIPhonePlatform()
    {
        global $private_is_iphone_platform;
        
        if (isset($private_is_iphone_platform))
            return $private_is_iphone_platform;
        
        $user_agent = $_SERVER['HTTP_USER_AGENT'];
        $private_is_iphone_platform = stristr($user_agent, 'iPhone') || 
            stristr($user_agent, 'iPod') ||
            stristr($_GET['platform'], 'iPhone');
        
        return $private_is_iphone_platform;
    }

This function returns whether or not the user agent is an iPhone or iPod touch, either by returning the state if already known, or determining it if not. It also allows testing the iPhone-optimized pages from your Mac by adding "platform=iphone" to a page's URL parameters (try it; it's fun!).

Not everyone would want the pages optimized, though: a great thing about the iPhone is MobileSafari does an excellent job of rendering "real" web pages. So I also added a checkbox at the bottom of every page to toggle iPhone-optimized mode off and on. The state is recorded in cookie. So I have another function to read that, on the iPhone platform:

    function getIsIPhoneOptimized()
    {
        global $private_is_iphone_optimized;
        
        if (isset($private_is_iphone_optimized))
            return $private_is_iphone_optimized;
        
        $private_is_iphone_optimized = getIsIPhonePlatform();
        
        if ($private_is_iphone_optimized && isset($_COOKIE['iphone_optimized']))
            $private_is_iphone_optimized = $_COOKIE['iphone_optimized'];
       
        return $private_is_iphone_optimized;
    }
Then the checkbox is actually output (in the footer's include file) via somewhat messy code that uses PHP to output the JavaScript to set the cookie and reload the page when the checkbox is toggled, and the checkbox itself:
    function outputIPhoneOptimizationCheckbox()
    {
        if (getIsIPhonePlatform())
        {
            $query_params = $_SERVER['QUERY_STRING'];
            
            if ($query_params != '')
                $query_params = '?' . $query_params;
            
            echo('<script type="text/javascript">' . "\n");
            echo('<!--' . "\n\n");
            echo('function iphoneOptimizedToggled()' . "\n");
            echo('{' . "\n");
            echo('  document.cookie=\'iphone_optimized=' .
                !getIsIPhoneOptimized() . '; path=/\';' . "\n");
            echo('  window.location.reload(true);' . "\n");
            echo('}' . "\n\n");
            echo('-->' . "\n");
            echo('</script>' . "\n\n");
            
            echo('<p><input type="checkbox" id="iphone_optimized_checkbox"
                onclick="iphoneOptimizedToggled()"');
            
            if (getIsIPhoneOptimized())
                echo(' checked="checked"');
            
            echo(' /><span id="iphone_optimized_label"
                onclick="iphoneOptimizedToggled()">
                Display site optimized for iPhone</span></input>' . "\n");
            echo('</p>');
        }
    }
And finally, the getIsIPhoneOptimized() function is called in the header to use iPhone-optimized or normal style sheets. This is actually a simplification; it actually uses several style sheets, including some common ones and some platform-dependent ones. It also sets the viewport appropriately for each platform — that is a key aspect for iPhone optimization:
    if (getIsIPhoneOptimized())
    {
        echo('<link rel="stylesheet" href="/iphone/header.css"
            type="text/css" media="all" />' . "\n");
        echo('<meta name="viewport"
            content="width=device-width, user-scalable=no" />' . "\n");
    }
    else
    {
        echo('<link rel="stylesheet" href="/mac/header.css"
            type="text/css" media="all" />' . "\n");
        echo('<meta name="viewport" content="width=900" />' . "\n");
    }
Of course, configuring the CSS appropriately is another story, but not too difficult... and very site-specific. Feel free to explore my CSS files if desired: I hope this is helpful. There are a number of other aspects, like fitting images in the available space, supporting movies that can play on the iPhone, and more. If there's interest, I might write more about this in the future.