By default all apps you deploy from Xcode will make it to your device with the Debug Build Configuration. This is useful during development, but it doesn’t optimise your code. It’s therefore easier to debug, but your app doesn’t run as fast as the final release version would.
Especially on older devices this can make a huge difference, particularly for your own personal apps that may never make it to the App Store.
There is a painless way to change how apps are deployed to your devices in Xcode. All we need is a distribution profile, just like the one we need for App Store submission. Next we’ll change the Run Scheme to use the Release Build Configuration. Here’s how to do that in Xcode 6.1.1:
- with your device selected, head over to Product – Scheme – Edit Scheme
- select Run from the list on the left
- change the Build Configuration from Debug to Release
- untick the “Debug executable” option
- deploy your app using the usual playback button
Users have reported a 60% speed increase on their devices.
Make sure the distribution profile is imported into Xcode and selected as explained here.
Further reading:
- http://stackoverflow.com/questions/5270586/xcode-difference-between-debug-and-release
- http://stackoverflow.com/questions/14460281/how-do-you-debug-an-issue-with-a-release-mode-build-in-ios
- http://stackoverflow.com/questions/19185540/run-release-build-of-ios-app-on-development-device
- http://stackoverflow.com/questions/8870074/how-to-test-the-release-build-on-device-with-xcode-4-2
Much like every time a new version of iOS is released, developers don’t find out what’s actually changed until everyone else. iOS 8.1 is no different, so here’s what’s new – straight from the update dialogue: 
Even though us developers get access to new versions of iOS, it doesn’t mean that Apple actually tell us what’s new in a release. iOS 8 is no exception.