This is a collection of OSS which helps you implement Flat Design UI on your current version of iOS (iOS5,6) just like that on iOS 7.
FlatUIKit
A collection of flat UI components.
UI7Kit
Backport flat-style UIKit from iOS7 to iOS5+.
iPhone Flat Design UI
A Xcode project which has many templates for Flat Design UI.
QBFlatButton
Flat Style UIButton.
FlatWebView
A subclass of UIWebView that hides the drop shadows behind said UIWebView.
Flat Pill Button
FlatButton
UI components which reproduce iOS7 effects
DKLiveBlur
Live blur effect similar to yahoo weather iOS app and iOS 7. This OSS uses Accelerate.framework, so the blur processing is extremely fast.
CFIFrostedOverlayView
A view that renders its superview with a gaussian blur like iOS 7's Control Center. This OSS uses GPUImage.
Parallax
A view that reproduces the parallax effect of the iOS7 home screen.
Flat UI kit for Photoshop
Free iOS 7 UI Kit
Start designing iOS 7 apps today with this comprehensive GUI kit for Photoshop. Absolutely every element you see is 100% vector and completely editable!