Android iPhone OS Comparison

David Thomas

April 12, 2010

1 History

1.1 Android

Android OS started as a project from Android Inc., based out of California. Theirideas and work caught the attention of Google, who absorbed their company. Themen behind Android, Andy Rubin, Nick Sears, Rich Miner, and Chris White headedup the team at Google to start an open source mobile phone operating system basedon the Linux kernel.[8] In November of 2007, The Open Handset Alliance consist-ing of Google, Texas Instruments, Broadcom Corporation,HTC, Intel, LG, MarvellTechnology Group, Motorola, Nvidia, Qualcomm, Samsung Electronics, Sprint Nex-tel and T-Mobile, released the first official public information regarding Android,including that it would use Linux kernel version 2.6. The Android source was re-leased to the public on October 21, 2008 using the Apache license. The Apachelicense, created by the Apache Software Foundation in January of 2004, allows forthe user of the software the ability to modify and distribute the software freely. Italso does not require that any kind of modifications to the software use the ApacheLicense. When a piece of software is redistributed with modifications, the originalcopyright, patent, trademark, and attribution notices must be included with noticesof modification to them.[8]

1.2 iPhone

The iPhone OS is a closed source operating system developed by Apple for use onthe iPhone, iPod Touch, and now to a modified extent, the iPad. It was initiallyreleased on June 29, 2007 and has received many updates since.[10] The OS consistsof four layers. The Core OS, Core Services, Media and Cocoa Touch. The biggest

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accomplishment of the iPhone OS was wielding the forefront of technology, such asmultitouch capabilities and internal accelerometers with an easy, friendly user inter-face. The interface is designed to make user of different interactions with the device,such as a switch in viewing mode from portrait to landscape. Another example is acommon use of shaking the device to signify an backspace or deletion. The iPhoneuses versions of many Mac OSX applications modified for the mobile phone environ-ment. For example, web browsing on the iPhone OS is done through Safari. Mailand Calendar events are handled through scaled down versions of Apple Mail andApple iCal.[9]

2 Supported Devices

2.1 Android

Android supports many innovative and industry standard features for mobile phones,as well as other platforms that Android could be adapted to in the future. For ex-ample, the graphics platform is expandable from traditional smart phone layoutsto 2D and 3D graphics using OpenGL over VGA.[8] Android supports all of themajor connectivity technologies from mobile phones using GSM/CDMA to morepersonal connections via Bluetooth and Wi-Fi. Android is equipped to use videoand still camera modes, touch screens, GPS, accelerometers, accelerated 3D graph-ics, and digital compasses. Android has codecs built in to support most populardigital media formats, such as H.263, H.264 (in3GP or MP4 container), MPEG-4SP, AMR, AMR-WB(in 3GP container),AAC, HE-AAC (in MP4 or 3GP container),MP3, MIDI, OGG Vorbis, WAV,JPEG, PNG, GIF, and BMP.[8] Currently thereare atleast 18 devices running Android available at retail currently. Many largehardware manufacturers such as HTC, Dell, Acer, Motorola, and Samsung all havedevices running Android with more companies such as Creative and Sony Ericssonon about to join the list. As mentioned earlier, Android is not exclusive to mobilephones. Creative Labs is working on an MP3 player that uses Android for advancedfunctionality.[8] It is meant to enter the same entry-level market as the iPod touch.The Zii Egg is designed for OEM retailers to rebrand and resell. It comes with ZiiL-abs Plaszma OS, but also supports Android. The Zii Egg is currently being offeredfor 399 dollars as a prerelease to developers and OEM retailers.

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2.2 iPhone

The iPhone OS runs exclusively on iPhone, iPod Touch, and iPad. All previousversions of the iPhone and iPod Touch are supported as well. This includes theiPhone, iPhone 3G, and iPhone 3GS released June 29, 2007, July 11, 2008, andJune 19, 2009 respectively. That is roughly one hardware update per year. TheiPod Touch 1G, iPod Touch 2G, and iPod Touch 3G released September 13, 2007,September 9, 2008, and September 9, 2009 respectively. The iPod Touch follows asimiliar one hardware update per year strategy as the iPhone. Only one version ofthe iPad is currently available, having been released on April 3, 2010. The iPhoneand iPod Touch both start from 199 dollars the iPad starts from 499 dollars

3 Hardware

3.1 Android

In regards to hardware and device support, Android supports many innovative andindustry standard features for mobile phones, as well as other platforms that Androidcould be adapted to in the future. For example, the graphics platform is expandablefrom traditional smart phone layouts to 2D and 3D graphics using OpenGL overVGA.[8] Android supports all of the major connectivity technologies from mobilephones using GSM/CDMA to more personal connections via Bluetooth and Wi-Fi. Android is equipped to use video and still camera modes, touch screens, GPS,accelerometers, accelerated 3D graphics, and digital compasses. Iphone also supportsthese same features, with exception CDMA since the iPhone is contractually boundto AT&T.[9]

Some of the official product specifications for the Zii Egg still have yet to bereleased, but it is known that both the iPod Touch and the Zii Egg come in 8GB,16GB, and 32GB models. The Zii egg sets itself apart by provided an expansion SDCard slot to allow up to another 32GB of flash storage. The screen size (3.5, 320x480pixels) is the same between the two, as well as the multitouch user interface. TheZii Egg includes GPS, where the iPod Touch does not. GPS is only a feature on theiPhone 3GS. The iPod Touch does not currently boast an onboard camera, but theZii Egg contains two. One rear facing HD camera, presumably for capturing videoand pictures, and one lower resolution, forward facing VGA camera used for videoconferencing. The HD content captured by the rear facing camera, as well as anyHD media from storage can be output to HDMI or component sources at resolutionsup to 1080p.

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3.2 iPhone, iPod Touch, and iPad

The iPhone 3GS utilizes a 600 MHz ARM 11 processor and can support OpenGLES 2.0 with 256MB of RAM. There is a 3.0 megapixel autofocus camera onboardcapable of 30 f.p.s. VGA video camera. There is a 7.2Mbps HSDPA system for 3G,4G and GSM connections. A Wifi chip as well as Bluetooth 2.1 are also included.The iPhone 3GS is 115.5 x 62.1 x 12.3mm and weighs 4.76 ounces. It comes in 16GBand 32GB models. The iPhone is powered by a 3.7V 1219 mAh Lithium Ion battery.The iPod Touch features the same 600 MHz ARM 11 processor capable of OpenGLES 2.0 as well as the 256MB of RAM. There is no camera on the iPod Touch or7.2Mbps HSDPA system, however the Wifi and Bluetooth are included. The iPodTouch is 110 x 61 x 8.4mm and weighs 4.1 ounces. Both the iPhone and iPod Touchhave a 3.5” touchscreen with a resolution of 320x480 pixels. The iPod Touch runs ona 3.7V 789 mAh Lithium Ion battery. The iPad runs on a 1 GHz Apple A4 PowerVRSGX 535 GPU with 256MB of RAM built in. The iPad comes in 16GB, 32GB and64GB models. There is an optional iPad model that comes with HSDPA systemto connect over GSM/Edge networks. Wifi and Bluetooth 2.1 come standard on alliPad models. The iPad has a touch screen that measure 9.7 inches diagonally witha resolution of 1024 x 768 pixels. The iPad is 24.3 x 19.0 x 1.3 cm and comes inbetween 1.5-1.6 lbs depending on if the 3G networking hardware is included. It runson a 25 wH Lithium Ion polymer battery. Comparatively, the iPhone gets 30 hoursaudio playback, 10 hours of video playback, the iPod Touch gets 30 hours audioplayback, 6 hours of video playback and the iPad gets 140 hours of audio playbackand 10 hours of video playback.[9]

4 SDK

4.1 Android

Applications for the Android OS are developed in Java using the open source Eclipsedevelopment environment. A special add on for Eclipse is required in order to developfor Android. This addon can be obtained from Google. All of the components fordeveloping on Android OS are free and open source, however, the programs do notneed to be open source. This is due to the Apache license that Android is releasedunder. Android applications are released under the Google-run Android Market.No special program is needed to download the applications or browse the Androidmarket, like how iPhone OS requires iTunes. Android applications can be developedon any platform, since Eclipse is open source and available for all major operating

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systems, including Windows, Linux, Mac OSX and Solaris.[2]

4.2 iPhone

For both the iPhone OS and Android, a well known development tool is used asthe basis of the SDK. For iPhone, the Mac exclusive xCode Application is used fordevelopment. The applications must be written in ObjectiveC, an object-orientedversion of C developed by Apple.[1] A free membership with Apple’s website foriPhone developers is required to download the necessary additions to xCode in orderto develop the applications. The free membership utilizes an iPhone virtual machinefor testing, but does not permit the developer to upload the application to an actualdevice. For that purpose, a 100 dollar upgraded membership is required that allowsbeta testing access and Apple App Store privileges. The beta testing access allowsthe developer to upload the application to up to ten iPod Touch or iPhone devicesfor field testing. The environment supported by xCode is Apple’s own Mac OSX.Therefore owning a Mac is required for developing applications on the iPhone.[1]

5 Thread Management System

5.1 Android

Android’s foundation comes from the linux kernel and its associated GNU, GPL, andLGNU libraries. The specific port of the linux kernel to the ARM architecture is notunique to Android however. It is very widely used in other embedded systems. Afew of the open source libraries driving Android included, Webkit, SQLite, OpenSSLand OpenGL ES. Webkit is a very prominent and fast technology that powers manydesktop web browsers, such as Apple’s Safari, Konquerer for KDE, and some of thetop of the line Nokia cell phone’s utilizing Symbian technology. SQLite is a verylightweight version of SQL that has been trimmed down to fit in less than 500kbof memory and can utilize the vast majority of SQL-92 functions. OpenSSL bringsthe same top of the line security found in all Mozilla Foundation products, AppleMac OSX, and Linux. OpenGL ES brings a subset of the OpenGL functions thatpowers many modern desktop computer games optimized for the mobile, embeddedplatform.[2] The Dalvik virtual machine is used instead of the much more widelyused Java Virtual Machine. Dalvik differs from Java in that it does not use JustIn Time compilation techniques. By forgoing the ability to read Java bytecode andinstead utilizing a dex bytecode native to Dalvik, Android can achieve much longerbattery life. A sacrifice with this decision came in that Android can not use standard

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Java SE applications and environments. In the topmost Application layer, howeverinvisible to the user, resides the service processes. Communication to them is handledover message buses. One notable example would be a contacts manager applicationplacing a phone call by utilizing the telephony service.[3]

There are four types applications or processes in the Android framework.[12]The types include User interface applications, intent listeners, services, and contentproviders. The user interface applications are self drawn visualizations of applica-tion, The intent listeners interface with the message bus to allow application andprocesses to communicate with each other. A service in Android functions similarto services in other operating systems. Services lack user interfaces, but provideintegral background functionality to applications. Content providers allow for datato be passed between applications. Android is unique in that it does not allow datato be accessed by outside processes. This makes Android the most secure mobileoperating system. In instances when data needs to be transferred, content providersregulate if it is secure.[12]

Figure 1: The structure of the Android OS Layers[12]

spectrum data technologies

Page 3 of 17 Spectrum Data Technologies, ! 2008

1.1 Google Android Google Android is a new mobile handset platform based on Linux, Apache Harmony1 and a

proprietary, for the moment at least2, custom virtual machine named Dalvik.

Figure 1 Overview of the Android Application Stack3

1.1.1 The Red Layer

The red layer from figure 1 represents the services offered by the Linux kernel and associated

GNU utility packages ported to the ARM4 architecture. These components are licensed under

the GNU General Public License, the GPL5, or the GNU Lesser General Public License, the LGPL6.

Being subject to the GNU GPL and LGPL licenses, these components are licensed with all source code included. Furthermore, due to the viral nature of the GPL license, any modification to this layer or derived work must be distributed as source to any 3rd parties using the same licensing terms. The GNU/Linux ARM port is mature, stable, and used in

many embedded projects both in and outside of Google7.

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5.2 iPhone

Mulithreaded applications are supported on iPhone OS because of the common rootswith Mac OSX. Every process contains at least one thread from which the main()function runs. That main thread can spawn helper threads to assist in execution.Each thread contains its own execution stack, even if it was spawned from anotherthread. However, all threads share the same virtual memory space and have thesame access rights. The operating system was designed this way so that Apple couldmaintain very close control on how overall performance of the devices.[4]

6 Memory Management

6.1 Android

Memory management in the Android OS is slightly more complicated than its iPhoneOS equivalent. That is because the iPhone OS does not allow third party applica-tions to run in the background currently. Androids ability to multitask means thata complex memory management system is necessary. When an application is nolonger in use, it is effectively put to sleep by the operating system. In this state,is consumes virtually no processing power. The Java foundation of Android bringsgarbage collection in to free up memory when needed. It functions similarly to itsdesktop counterpart in that it runs in the background and deletes unused objectswhen space is needed.[12]

6.2 iPhone

The iPhones basis in Objective C means that it utilizes similar memory managementfunctionality as it desktop counterpart.[1] Objective C utilizes reference counting asa way of determining if an object is eligible to be deleted. It is only eligible to bedeleted if it is no longer needed by any other class. Each object maintains a referencecount of how many classes are currently using it. Once that count reaches zero, theobject can be safely deleted. This is very similar to garbage collection in Java. Themain difference is that Java relies on code running in the background constantly tomake these checks for the safety of deletion. Objective C has Java garbage collectionbuilt in to it, however it is not able to be used on the iPhone. The reference count isnot automatically maintained, the programmer must manually account for it. Thisis accomplished with object ownership. Object ownership is when a section of codedeclares that the specific object is necessary to its functionality.[1] An object can

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have multiple owners. In additions to declaring ownership, owners must releasetheir ownership of an object as well. Ownership is not required for object use,however it is recommended for any extended use. While using an object temporarilywithout ownership, there is a risk of the object being deleted while it is still needed.When adding an object to an array, ownership does not need to be explicitly taken;ownership is automatically given to the array.[1]

7 Networking

Android supports all of the major connectivity technologies from mobile phones usingGSM/CDMA to more personal connections via Bluetooth and Wi-Fi. A mobilephone carrier and contract, as well as a mobile phone running Android are requiredto utilize the GSM/CDMA connectivity. The non mobile phone devices, such asthe Creative Zii Egg, running Android can only utilize Wi-Fi, Bluetooth and thedirect I/O through data cable.[8] Tethering is not allowed using an Android devicedue to contractual agreements with T-Mobile. The Apple iPhone only supportsGSM because of the exclusive rights AT&T has over the iPhone market. Tetheringhas only recently become available to the iPhone as a result of much user protest.The iPhone has Wi-Fi and limited Bluetooth capabilities.[9] Ipod Touch owners areunable to utilize GSM networking due to the lack of contract and lack of hardware onthe non-mobile phone device. Ipod Touches are however capable of the same Wi-Fiand limited Bluetooth connectivity.[9]

8 Power Management

8.1 Android

Android has its own specific power management frame work built on top the stan-dard Linux power management framework. The ideaology underlying Android powermanagement strategy is that the CPU should not consume power if there are no pro-cesses that require power. Android utilizes wake locks to request CPU resources.If there are no wake locks in an active state, the CPU gets shut down to avoidwasting power. Android has facilities similiar to the iPhone for the user to managepower by allowing specific networking devices to be shut down to save power, aswell as an additional task manager application to increase user control over powerconsumption.[12]

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8.2 iPhone

Power management is left to the user on the iPhone. Options to disable each ofthe five major connectivity networks are available to the user in the settings menu.The most power consuming is the mobile phone service, or 3G network device. Thiscan be disabled separately from the the 2G network device, for when the user is ina rural area without 3G service. Using only 2G can save a significant amount ofbattery power. The next most power consuming device is Wi-Fi. Following Wi-Fiis 2G networking, Bluetooth then GPS. All of these can be individually disabled bythe user to provide a custom power management solution.[11]

9 Comparison

9.1 Development Environment and Application Distribution

For both the iPhone OS and Android, a well known development tool is used asthe basis of the SDK. For iPhone, the Mac exclusive xCode Application is used fordevelopment. The applications must be written in ObjectiveC, an object-orientedversion of C developed by Apple.[1] A free membership with Apple’s website foriPhone developers is required to download the necessary additions to xCode in orderto develop the applications. The free membership utilizes an iPhone virtual machinefor testing, but does not permit the developer to upload the application to an actualdevice. For that purpose, a 100 dollar upgraded membership is required that allowsbeta testing access and Apple App Store privileges. The beta testing access allowsthe developer to upload the application to up to ten iPod Touch or iPhone devicesfor field testing. The App Store privileges allows the developer the ability to submitthe finished application to Apple for approval. Upon approval, the application willbe made available for distribution on the Apple App Store by Apple. The developeris entitled to 70 percent of the profits from the sale of the application, with theremaining 30 percent going to Apple. The Apple iTunes application is required toaccess the App Store.[9] Applications for the Android OS are developed in Java usingthe open source Eclipse development environment. A special add on for Eclipse isrequired in order to develop for Android.[2] This add on can be obtained from Google.All of the component for developing on Android OS are free and open source, however,the programs do not need to be open source. This is due to the Apache license thatAndroid is released under. Android applications are released under the Google-runAndroid Market. This Developers of priced applications receive 70 percent of theapplication price, with the remaining 30 percent distributed between the various

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carriers that offer Android OS mobile phones. Revenue earned from the AndroidMarket is paid to developers via Google Checkout merchant accounts.

9.2 Ease to Port Applications

Porting a fully fledged application to either Android and iPhone OS will require asubstantial amount of work regardless of which platform you choose. Much of theeffort depends on the originating framework and platform of the application. Forexample, if the application was originally written for Mac OSX using Apples Objec-tiveC, then porting it to iPhone will be much easier than porting it to Android.[1]Since iPhone OS applications are written in a variant of C, any application originallywritten in C will port to iPhone much easier than the Java based Android. If theapplication was originally designed for Java, then it will be much easier to port tothe Android OS with the Android plugin with Eclipse.[2]

9.3 Virtualization

In Android, the Dalvik virtual machine is used instead of the much more widelyused Java Virtual Machine. Dalvik differs from Java in that it does not use JustIn Time compilation techniques. By forgoing the ability to read Java bytecode andinstead utilizing a dex bytecode native to Dalvik, Android can achieve much longerbattery life. A sacrifice with this decision came in that Android can not use standardJava SE applications and environments. In the topmost Application layer, howeverinvisible to the user, resides the service processes. Communication to them is handledover message buses. One notable example would be a contacts manager applicationplacing a phone call by utilizing the telephony service.

9.4 Reliability and Security

Both Android and iPhone OS have proven to be more secure than their full sizedcomputer counterparts. Both mobile operating systems greatly benefit from the in-herent security of their parent desktop operating systems. The Mac OSX elements iniPhone OS provide much of the same platform specific security that Mac computersystems have.[10] The Linux kernel in Android yields its same security benefits toAndroid as well. IPhone OS does not allow for multiple processes to be run in thebackground, so this prevents many sleeper processes that could violate the integrityand privacy of a users data.[10] Also, in order to be released for the public on theApple iPhone App Store, applications must be approved by Apple. Their source is

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examined for possible malicious content by the professionals at Apple.[1] Androidsprinciples prevent the regulation of applications at the level of Apple, however thedata protection services in the operating system prevent malicious software from be-ing able to access important information. Android prevents one processes from accessthe data in another process. This is not fool proof though. There are methods toaccess the sensitive data once the target process has been terminated. If the memoryblocks have not been zeroed out, a malicious process could access the sensitive dataleft behind by the originating process.

9.5 Future and Other Factors

The future of both Android and iPhone OS are very bright. The new version ofAndroid coming out, Android 2.5 (Froyo) is expected to implement a new PortableApp Engine, which would allow Android devices to run iPhone and Palm Pre ap-plications. There are only about 2000 Palm Pre applications available, but thereare more than 150,000 iPhone applications available. This would greatly bolsterthe application selection available to Android devices as well as bring unity to themobile phone market. This feature came from the 20 percent project of two Googleengineers. Google allows its employees to spend 20 percent of their time at workdeveloping their own ideas. The groundwork for a new charging technology will beadded to support charging via WiFi signals. This technology should be similar tothe RCA AirPower technology. Some smaller bug fixes, such as calendar features aswell as new Translation application from Google are also expected to be included.[7]

The iPhone 4.0 OS, announced on April 8, will include some much needed featuresto bring iPhone to the same level of customization that Android users enjoy. Theheadline feature of iPhone OS 4.0 is the addition of multitasking. This has been afeature of Android since its release. Home screen folder options, allowing users toorganize applications more efficiently and store more applications on their deviceshas also been added. The mail application has received some upgrades, including aunified inbox for users with multiple email account. A new advertising technology,known as iAd will also be making its debut in the new version of the OS. The iAdtechnology will allow location specific ads to be displayed for iPhone users. Thisaddition has been controversial due to the privacy issues it introduces.[6]

10 Conclusion

In conclusion, the Android OS is a far more open ended system that is ahead of theiPhone in all things technological. The iPhone leads in market share primarily do to

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its head start in the marketplace. I feel that the Android OS is a superior choice tothe iPhone OS, but by a slim margin. The innovation that is known to come fromthe open source community should not be overlooked by Apple. Apple is known forpaving the way for many new markets of mobile computing, but the lack options forusers in terms of customization, as well as background processing as put them in aposition chasing the Android OS. The one major advantage Apple has over the restof the market is the tight control it maintains by only allowing the iPhone OS torun on its own device. With that control, all aspects of device performance can becontrolled tightly.

References

[1] (2010, April 12) IPhone Dev Center. [Online]. Available:http://developer.apple.com/iphone/index.action

[2] (2010, April 10) Android Developers. [Online]. Available:http://developer.android.com/index.html?u

[3] (2010, April 10) Simple Thread Management - Java - Android. [Online]. Avail-able: http://stackoverflow.com/questions/

[4] (2010, April 10) IPhone Thread Management . [Online]. Available:http://developer.apple.com/iPhone/library/

[5] (2010, April 8) Virtualization Coming to Android. [Online]. Available:http://www.pcmag.com/article2/0,2817,2340980,00.asp

[6] (2010, April 11) Apple Showcases IPhone 4.0 Features. [Online]. Available:http://www.macworld.com/article/150490/2010/04/

[7] (2010, April 3) Froyo and Gingerbread to Bring Unity to Android. [Online].Available: http://news.softpedia.com/news/

[8] (2010, March 8) Android (operating System). [Online]. Available:http://en.wikipedia.org/wiki/Android

[9] (2010, March 7) List of IPhone OS Devices. [Online]. Available:http://en.wikipedia.org/wiki/IPhone

[10] A. Hoog and K. G. (2010, March 14) IPhone Forensics

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[11] C. Rubicon. (2010, March 14) The Apple IPhone: Successes and Challengesfor the Mobile Industry

[12] Spectrum Data Technologies. (2010, March 7) A Spectrum White Paper:Thoughts on Google Android

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