TweetFollow Us on Twitter

Developing for the iPhone

Volume Number: 23 (2007)
Issue Number: 08
Column Tag: iPhone

Developing for the iPhone

OR: how I learned to stop worrying and love Web 2.0

by Marc S. Ressl

Introduction

The iPhone has finally come to us. After several months of speculation, jokes, disappointments and surprises, the incredible device hit the streets. In this article we will talk a little bit about the recent developments in the iPhone scene, about the kind of applications you can write for the iPhone, and about the ways you can implement them. We'll also discuss some human interface aspects, so you can start writing intuitive applications that "just work".

The missing software development kit

Let's talk a little bit about history. It was January 9th, 2007, a beautiful Tuesday morning at the MacWorld conference in San Francisco when Steve Jobs introduced the "next big thing", the iPhone.

During the following months the hype and spin grew to epic proportions. Rumor had it that the iPhone would be capable of some sort of third-party application development.

But in June, at Apple's developer conference WWDC 2007, the unexpected happened. Based on the fact that the full Safari engine is inside the phone, Steve Jobs introduced a "very sweet solution" for developing apps. Web 2.0 applications can look and behave exactly like iPhone applications, he claimed.

Most people weren't expecting a full-blown SDK in a version 1.0 device. However, his announcement let down some developers, as Jobs was hardly telling anything new. This feeling was only exacerbated by Jobs' claims from a week before, when he said that "...you can't do that stuff in a browser", while discussing the iPhone's internal Google Maps client.

In spite of Apple's real reasons for not opening up the iPhone (yet), there are many advantages with web applications:

· Security. Keeping third-party web applications sand-boxed in Safari protects the device and networks from software pathogens. The https protocol provides secure communications over the Internet. A stolen iPhone is no security concern, as no sensitive application data is stored locally. There is also no need for an application certificate, as with Symbian.

· Installations. No installation is needed, as an application just exists as a URL, a username and a password. As a side-effect, applications get copy protection. Your code stays on the server.

· Updates. Web-apps only need to be updated on the server. Update once, update everywhere.

· Access. Being platform-agnostic, a web-app for the iPhone works on a regular web browser and on other mobile browsers as well, wherever you are.

· Usability. HTML controls, enhanced with JavaScript, provide all the flexibility you could expect from a traditional application. Besides, the pinch gesture always works as expected.

· New ways for earning revenue. You can charge for usage of your app. Another possibility is to add advertisements to it.

· Efficient data transmission. There has been some criticism that web-apps would have a large overhead. But Safari has a cache, and Web 2.0 apps can be highly optimized.

Of course, the list of disadvantages is also quite long:

· Web applications can't be stored on the local file system, they are not available offline. Forget widgets à la Mac OS X.

· No access to the iPhone's resources. No direct sound playback or recording, no direct access to the camera, no interfacing with Bluetooth, no direct access to the Internet, no direct access to the cellular network, no direct access to iPhone's sensors.

· Computationally intensive tasks are not possible. No sound, image or video processing.

· Limited access to the multi-touch interface.

· Containment. Since web-apps are contained in Safari, they cannot call your attention while Safari is out of focus.

· No direct links to the applications from the iPhone home screen. If you want to open an application you have to open a Safari bookmark, and this is odd.

· Bills. Data service bills might get pretty hefty when roaming.

· This is not confirmed at the time of this writing, but there appears to be no access to the data on the local file system.

I want to write an application for the iPhone

Want to write an app for the iPhone? You should ask yourself first if it is feasible.

It should be feasible if your requirements are not on the list of disadvantages we just mentioned. Particularly well suited are applications that demand permanent connection, like instant messengers, remote control or directory look-up services. Group collaboration tools, regular office applications, calculators, converters, RSS readers, news tickers, and mobile mini-games are also good candidates.

But sadly there are many things that can't be implemented: Skype-like VoIP (obviously not in the interest of cellular operators), a voice recorder (for voice blogging purposes, perhaps?), games (I certainly would love MAME or ScummVM for iPhone), third-party media players (like VLC or MPlayer) and VNC (this might be possible with Web 2.0, albeit slowly). And many futuristic applications using the camera, microphone, Bluetooth or motion sensors are just not possible at the time being.

To see an example of what is feasible consider Google Docs & Spreadsheets. It is a powerful online office application that runs on the iPhone. And "iGoogle" is a personalized homepage with many customizable "Google Gadgets". It even accepts user-submitted gadgets.

It is clearly visible that Apple is heading in an open-standards, web-based direction. I myself can see many benefits in this move, as more and more online web applications might end up replacing traditional VPN systems with online, secure document viewing/editing and group collaboration tools. Might there be a big market about to be exploited?

The soul of a web application

How does one start writing a web application? Well, if you have something that serves web pages you are done, it'll work on the iPhone. I have always had a very good experience with AMP (Apache, mySQL and PHP), and do recommend it. You can easily find AMP (LAMP or MAMP) tutorials on the web. Other interesting frameworks are Ruby on Rails and Java+any application server.

As a first step, you should think about the web-app client-server communication. It will have a huge impact on people's patience (and maybe on their phone bills, too) if you transmit too much data. Remember the iPhone is GSM/EDGE.

The most straightforward approach is a classic HTTP request>response scheme. You display an HTML form, receive the variables from the form, and respond with the requested information. This simple approach works well for directory look-ups.

The problem with this scheme is complex interfaces that require minor screen updates (as a Web 2.0 office application certainly would). The overhead of HTML pages and forms will quickly render such a web-app unusable. Fortunately, one can use Ajax (Asynchronous JavaScript and XML) to solve this issue. JavaScript provides the XMLHttpRequest class that lets a web browser send asynchronous messages to a web server and receive a response. The JavaScript client on the browser can then update the page accordingly, with no reloading at all.

Let's see an example of a web page that automatically fills in a city name from a ZIP code. The HTML code for this example is:

<input type="text" id="zip" name="zip" onblur="getCityFromZip();"> <input type="text" id="city" name="city">

The onblur event starts the getCityFromZip() function when the user leaves focus of the zip field. Shown below is the JavaScript code that performs the look-up:

<script type="text/javascript" language="JavaScript">
// Create the HTTP object
function getHTTPObject() {
   var xmlhttp;
   if (typeof XMLHttpRequest != 'undefined') {
      try {
         xmlhttp = new XMLHttpRequest();
    } catch (e) {
         xmlhttp = false;
    }
   }
   return xmlhttp;
}
var http = new getHTTPObject();
// Look-up function
var url = "http://www.example.com/getCity.php?zip=";
function getCityFromZipcode() {
  var zip = document.getElementById("zip").value;
  http.open("GET", url+escape(zip), true);
  http.onreadystatechange = handleHttpResponse;
  http.send(null);
}
// HTTP response handler
function handleHttpResponse() {
  if (http.readyState == 4) {
    // Split the comma delimited response into an array
    document.getElementById('city').value = http.responseText;
  }
}
</script>

getHTTPObject() initializes the 'http' variable with an XMLHttpRequest object. A call to getCityFromZip() sets the request's http handler to handleHttpResponse(). It also starts a GET web request to:

   http://www.example.com/getCity.php?zip=[zipcode]

When the server answers, handleHttpResponse() takes over and updates the HTML element 'city' with the response from the GET request. In this example, the http response from the server is read directly. When you deal with complex data types an XML container might not be a bad idea.

How can you optimize your web-app? You can start by separating static and dynamic content. If static content is in a separate file it will be loaded only once, reducing data flow. You can get dynamic content with the XMLHttpRequest class described before. The same optimization can also be applied to JavaScript code. Consider creating a .js file for JavaScript code common to many URLs. Yet another optimization is to minimize the data flow of the dynamic requests: keep variable names short, keep URLs short. Try to bundle multiple dynamic requests to avoid HTTP overhead. Also, try to use HTTP GET requests, they have a smaller overhead than a POST (unless you have a lot of data). You can improve responsiveness by putting all user interface screens in a single .html file and using <DIV> styles to show only the one you currently need. It will take longer to load on the first time, but Safari caches content, so it will pay off soon. Final advise: enable gzip compression on the server, it helps when and if the browser allows it (Safari does). By following these guidelines, you will make many users happy.

The face of a web application

Now you know a little bit about the internals of good web-apps, but there is still something missing: the user interface.

It is unfortunate that so many developers disregard user interface design. Horrible, unintuitive apps are out there, and this is particularly true of mobile phone applications. I am sure you can make a difference. UIs are not just decor, they are what your users work with.

The iPhone screen

The iPhone screen is 320x480 pixels. At 160 pixels per inch, this is two by three inches. But HTML page width is not important, as iPhone's Safari is resolution independent (it adjusts page width automatically). It is nevertheless a good idea to limit HTML page width to 480 pixels, as this is the iPhone's largest native resolution.

You should also consider that your application can be viewed in either portrait or landscape mode. When viewed in portrait mode, an application gets approximately 320x355 visible pixels. In landscape mode, about 195x480 pixels are visible. When scrolling down, additional 60 or so pixels get available from the top of the title/address bar.

You should always choose font sizes that are easy to read in both portrait and landscape modes.

Controls

A great user interface is grandmother-proof. iPhone has one, so make no exception! A typical finger is 1/2 inch thick, so you should never pack more than 4 or 5 buttons in a row. The buttons should also be approximately the size of a finger.

When selected, text-entry fields open up the virtual keyboard. Consider resizing all HTML input elements so that they are easily accessible on the iPhone's screen.

In order to send an email from a form, link to a mailto: [email address] URI. At the time of this writing, this is unconfirmed, but most likely you can start a phone call by linking to a tel: [phone number here] URI (RFC 2806 standard).

Interaction

This is probably the most important, but also the hardest aspect to achieve, as it depends on the application. General guidelines are: keep everything as clean as possible. Never have more than eight user interface elements visible at the same time. The human brain is not good at dealing with more than eight things at once. You can use an <iframe> to emulate the iPhone's scrolling center part of the screen. Attempt to use the same symbols and logic as in the rest of the phone. Consider the flow of the different screens of your user interface. Is everything as simple as possible? Is it possible to accommodate your user interface so that users don't have to re-learn things they know from somewhere else?

Always keep asking yourself how your UI can be improved. And read Apple's Human Interface Guidelines, they are an excellent reference.

Eye candy

If you want to create a nice user experience, attempt to integrate your style with the iPhone's UI style. Split content and presentation with HTML/CSS (this will also reduce data flow). You can do pretty amazing animations in JavaScript. Check out this site for some examples: http://script.aculo.us/

An example under the spotlight

This article came to be because I was looking for an iPhone ssh client and simply couldn't find one. So, I started developing a Web 2.0 ssh client, as this was the one thing from keeping me buying an iPhone.

Luckily, I found the open-source Ajaxterm project. They were doing something similar to what I had in mind. Only the user interface had to be adapted.

So how does Ajaxterm work? It consists of a web client written in JavaScript, and a web server running in python. The web client periodically polls the server for screen updates. The web client also sends any key presses to the server.

What was needed to adapt Ajaxterm to the iPhone?

Ajaxterm gets key events through the JavaScript "onkeypressed" event. Unfortunately, this is not supported on the iPhone. Therefore, I added a text input control below the console screen, and several buttons for cursors, control and other special keys. The UI elements were arranged so the most common keys are close to where you actually work. The least used key combinations are hidden behind an alternative button control.

You can test the ssh client as well as download the source code at this URL:

http://www-personal.umich.edu/~mressl/webshell

What does the future hold?

In my opinion Web 2.0 (JavaScript + Ajax + XML + XHTML + RSS) is much more powerful than many believe. There are lots of limitations: no local storage, no access to iPhone's resources, limited computing resources, limited access to the multi-touch interface. But except for the applications discussed previously, I can't find a serious software limitation for iPhone.

Nevertheless, I hope that we will soon see a native iPhone software development kit. It will trigger a whole new generation of applications that we are not even capable of dreaming right now. Just imagine what a multi-touch controller with accelerometers and Bluetooth could do to a mobile game...


Marc S. Ressl is a senior developer in the cell phone business. He presently designs web applications using open-source technologies. He is also experienced in computer security and user interface design. You can reach him at mressl@umich.edu.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Lyn 1.5.11 - Lightweight image browser a...
Lyn is a lightweight and fast image browser and viewer designed for photographers, graphic artists and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it... Read more
NeoOffice 2014.11 - Mac-tailored, OpenOf...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
LaunchBar 6.4 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Remotix 3.1.4 - Access all your computer...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more
DesktopLyrics 2.6.6 - Displays current i...
DesktopLyrics is an application that displays the lyrics of the song currently playing in "iTunes" right on your desktop. The lyrics for the song have to be set in iTunes; DesktopLyrics does nothing... Read more
VOX 2.5.1 - Music player that supports m...
VOX is a beautiful music player that supports many filetypes. The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all... Read more
NetNewsWire 4.0.0 - RSS and Atom news re...
NetNewsWire is the best way to keep up with the sites and authors you read most regularly. Let NetNewsWire pull down the latest articles, and read them in a distraction-free and Mac-like way. Native... Read more
MacUpdate Desktop 6.0.6 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
ForkLift 2.6.5 - Powerful file manager:...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
Drive Genius 4.1.0 - Powerful system uti...
Drive Genius 4 gives you faster performance from your Mac while also protecting it. The award-winning and improved DrivePulse feature alerts you to hard drive issues before they become major problems... Read more

Auroch Digital is Bringing Back Games Wo...
| Read more »
Carbo - Handwriting in the Digital Age...
Carbo - Handwriting in the Digital Age 1.0 Device: iOS Universal Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Draggy Dead (Games)
Draggy Dead 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: Ditch your dead end job and take up a rewarding career in Grave Robbing today!Guide the recently deceased to a fun filled life of... | Read more »
Bad Dinos (Games)
Bad Dinos 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Apple Watch isn't Great as a Fi...
| Read more »
Show the World What You See With Stre.am...
Live broadcasting is getting popular on mobile devices, which is why you can now get Stre.am, by Infinite Takes. [Read more] | Read more »
PhotoTime's 2.1 Update Adds Apple W...
The latest PhotoTime update is adding even more functionality to the handy photo organizing app. Yep, including Apple Watch support. [Read more] | Read more »
Oh My Glob! Adventure Time Puzzle Quest...
Finn and Jake are taking over D3 Go!'s popular puzzle game series in the upcoming Adventure Time Puzzle Quest. [Read more] | Read more »
Earthcore: Shattered Elements - Tips, Tr...
At first glance, Earthcore: Shattered Elements seems like a rather simple card-battling game. Once you’re introduced to skills that will change quite a bit. Even more so once you start to acquire hero cards. But it’s not so complicated that we... | Read more »
Dungeon999F (Games)
Dungeon999F 1.33 Device: iOS Universal Category: Games Price: $.99, Version: 1.33 (iTunes) Description: "The game you must play at least once in your life!" "The game with potential of million downloads globally!" ...is what the... | Read more »

Price Scanner via MacPrices.net

OtterBox Maximizes Portability, Productivity...
From the kitchen recipe book to the boarsroom presentation, the OtterBox Agility Tablet System turns tablets into one of the most versatile pieces of handheld technology available. Available now, the... Read more
Launch of New Car App Gallery and Open Develo...
Automatic, a company on a mission to bring the power of the Internet into every car, has announced the launch of the Automatic App Gallery, an app store for nearly every car or truck on the road... Read more
Memorial Day Weekend Sale: 13-inch 1.6GHz Mac...
Best Buy has the new 13″ 1.6GHz/128GB MacBook Air on sale for $849 on their online store this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders... Read more
Memorial Day Weekend Sale: 27-inch 3.5GHz 5K...
Best Buy has the 27″ 3.5GHz 5K iMac on sale for $2099.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary.... Read more
Sale! 16GB iPad mini 3 for $349, save $50
B&H Photo has the 16GB iPad mini 3 WiFi on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model. Read more
Price drop on 2014 15-inch Retina MacBook Pro...
B&H Photo has dropped prices on 2014 15″ Retina MacBook Pros by $200. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799.99 save $200 - 15″ 2.5GHz... Read more
With a Mission to Make Mobile Free, Scratch W...
Scratch Wireless, claiming to be the world’s first truly free mobile service, has announced the availability of a new Scratch-enabled Android smartphone, the Coolpad Arise. The smartphone is equipped... Read more
First-Ever Titanium Alloy Curved iPhone 6 Scr...
One of the most common problems with mobile phones is damage to the screens. The slightest drop can cause a dreaded spider web of gashes and cracks in the glass panel surface that can cost $hundreds... Read more
Preorder new 12-inch MacBook, $10 off, save o...
Adorama has new 12″ Retina MacBooks available for preorder for $10 off MSRP including free shipping plus NY & NJ sales tax only. For a limited time, Adorama will include a free Apple USB-C to USB... Read more
Will iOS 9 Finally Bring Productivity Friendl...
Ah, the irony. From its original announcement in 2010, Apple has doggedly insisted that the iPad remain “simple,” thus arbitrarily limiting its considerable potential as a content creation and... Read more

Jobs Board

*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
Business Development Manager - *Apple* Pay...
**Job Summary** Apple Pay is seeking an experienced Business Development professional to join the Apple Pay team to develop partnerships and strategic alliances with Read more
Project Manager, *Apple* Retail New Store O...
**Job Summary** An Apple Retail New Store Openings & Remodels Project Manager is responsible for successfully managing the openings, remodels, and small works of Read more
SW QA Engineer - *Apple* TV - Apple (United...
**Job Summary** The Apple TV team is looking for experienced Quality Assurance Engineers with a passion for delivering first in class home entertainment solutions. **Key Read more
Partner Marketing Manager - *Apple* Pay - A...
**Job Summary** The Apple Pay partner marketing team is looking for a marketing manager to develop and drive US marketing programs with our financial institution Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.