This is part one of a two part series focused on the iPhone 4.0 Operating System (OS) recently announced by Apple.

Last Thursday’s announcement of the upcoming release of version 4 of the iPhone OS platform was billed by Apple as the biggest release yet for its operating system (OS).  This operating system powers the iPhone, iPod Touch and now the iPad. The announcement refers to 1500 new APIs (application programming interface) that will be available for developers, giving them access to a multitude of new features and deeper access to hardware features that were previously only available to Apple.

Although the fine details are available only to developers, the presentation given by Steve Jobs and colleagues was a good overview of the most important new features. An excellent summary of the features was also done by Gizmodo and Engadget.


The announcement most widely reported, of course, was multitasking. Many in the medical community have suggested the ability of third party applications to run in the background is a necessary feature for wider adoption of the iPhone and iPad in health IT – we haven’t always agreed. While good application design can at least partially obviate this restriction, there is clearly an advantage to an application retaining its exact state every time it’s re-entered. Furthermore, some applications may need to generate alerts or messages, even while not in the foreground.

Apple has been rightly concerned that giving third party applications license to run in the background could decrease CPU performance and reduce battery life. The solution implemented in iPhone OS 4.0 is simultaneously elegant and transparent to the user. According to Apple, this involved surveying the population of applications in the App store and identifying the types of background services 3rd party applications would most be needed for. They then built these functions directly into the operating system. This way, application developers can implement certain key background processes with minimal additional code while Apple can be certain that these processes are consistent across applications and extremely power efficient.  An example of this will be given below.

Background services

Not surprisingly, the first such service mentioned is background audio streaming. High on the wish list of many iPhone (and now iPad) users is the ability to listen to the internet radio, such as, while working. That is now possible to do – and if the demonstration Apple gave is to be believed, this type of functionality will have negligible effect on battery life and CPU performance. I am not sure what the medical application for this might be but the next feature mentioned, background voice-over-IP (VOIP), I can certainly imagine being helpful in the hospital setting.

This feature allows VOIP services, such as Skype, to run in the background. This not only allows a Skype conversation to continue after quitting the application, but also allows the user to receive Skype phone calls without the application running.  In a hospital where phone service is unreliable, but where Wi-Fi is widespread, this could be very useful for communicating between team members. I can imagine this being directly built into electronic health record (EHR) applications so you could initiate a conversation with a colleague without having to leave the app.

Also coming in iPhone 4.0 is background location services. This allows applications that rely on GPS or wireless positioning, e.g. turn-by-turn navigation and location-based social applications like Loopt, to access location data in the background.  This added functionality has huge potentials for health care applications.  A weight loss application could run in the background and measure how much you walk in a work day and translate this into calories burned – all while you do normal tasks on your iPhone.  This monitoring of mobility could also be used to study post op surgical patients – to see the right balance of physical activity after certain procedures.

Fast-app switching

Another system-wide service being deployed as part of the multi-tasking package is fast app switching. This service, available to developers for any application, allows the developer to “freeze” the user interface whenever a user leaves the application. The application remains in a “suspended” mode, drawing minimal resources, until the user returns to the app and resumes working.  To the user, when reopening the app, it appears the application never quit.

The user-interface for accessing multi-tasked applications was also elegant. Double clicking the home button causes the current view to slide upwards revealing a row of icons, representing the currently running apps.  In the demonstration, Jobs could be seen repeatedly switching between applications in fractions of seconds.

For the typical multi-tasking physician, probably talking on the phone, while writing on the chart, and quickly looking up clinical data or contact information on her phone, this will no doubt be a great new addition.


Multitasking functionality should be a welcome addition for those in the health IT industry working on electronic health records for the iPhone, such as Epocrates.  Having the ability to write a patients note – switching over to safari to access key information via the web and then going right back to your patient note without hesitation should make more healthcare providers accepting of the iPhone OS platform in practice.

Iltifat Husain contributed to this post