Inside iOS 4: Missing features for iPhone 3G users
iOS 4 eats up RAM
Developers report that iOS 4 uses a lot of RAM. In an article comment, Hrissan notes, "Ive looked at the list of processes & their real memory usage in Xcode for my iPhone 3G after launching and quitting a large game (to make iOS free as much memory as possible).
Daemons for features switched off:
BTServer: 684KB (I have bluetooth off)
accessory: 550KB (I never use accessories)
lockdownd: 1.56MB (Monitoring activation status I have an unlocked
ptpd: 1.29MB (Tethering, I have tethering off)
Also look at these 2 daemons:
aosnotifyd: 2.6MB (Mobile.me sync so much for 1 open socket?)
dataaccessd: 3.74MB (Exchange calendar sync oh my God!)
"I love new iOS 4 features, but it seems memory optimization was not the top priority. It is possible even that supporting 3G was decided on the later phase of development."
No wallpaper for iPhone 3G in iOS 4
While the increased memory requirements of iOS 4 multitasking are easy to understand, some have questioned why Apple doesn't support background wallpapers on Home screens. One user who emailed Apple's chief executive Steve Jobs about the issue got a characteristically terse reply (as noted by Gizmodo) stating, "The icon animation with backgrounds didn't perform well enough."
While jailbreakers have been putting background images on the Home page of the iPhone for years, Apple's implementation of wallpapers is more sophisticated, using drop shadows to isolate icons and their text labels from the underlying graphic to improve their appearance and readability. The new iOS 4 also renders shadows under the icon dock.
Apple found that doing this on the significantly slower iPhone 3G resulted in a significant slowdown that made it perform badly enough to simply drop the feature rather than ship something that either looked bad or felt slow and jerky. Jailbreakers report that activating wallpapers on the iPhone 3G under iOS 4 does indeed result in sluggish performance.
No Bluetooth keyboard support for iPhone 3G in iOS 4
Deactivated support for iOS 4's Bluetooth keyboard feature is also a hardware issue. The first two generations of iPhones supplied basic Bluetooth 2.0 support. Starting with the iPhone 3GS, Apple added Bluetooth 2.1 + EDR (Enhanced Data Rate) capable hardware.
The newer specification improves device setup with the "Secure Simple Pairing" mechanism and implements "Extended Inquiry Response," which reduces power consumption in low-power mode.
Enhanced encryption in hardware
Data protection is a new feature in iOS 4 that "enhances the built-in hardware encryption [of the iPhone 3GS and 3rd generation iPod touch] by protecting the hardware encryption keys with your passcode," according to an Apple tech support article.
"This provides an additional layer of protection for your email messages and attachments. Third-party applications can use the data protection APIs in iOS 4 to further protect application data."
The original iPhone and iPhone 3G along with the first two generations of iPod touch lack hardware support for data encryption, so none of them could support the new feature that improves upon it either. The iPhone 3GS' hardware encryption was recently the subject of reports that assailed the feature as "worthless."