#JMIBlur

JMIBlur is an attempt to replicate the live blur view that Apple is using all over [REDACTED]. It uses the private CAFilter class, so it's probably a no-no. This implementation was made using Xcode 4.6 and iOS 6.1, but should also work on future versions of Apple's mobile OS.

##How do I use it?

1. Include the following files in your project:

   • JMIBlur.h
   • JMIBlurStyle.h
   • JMIBlurView.m|h
   • JMIBlurLayer.m|h

2. Import JMIBlur.h

3. Create a JMIBlurView or JMIBlurLayer with one of the following styles:

   • blurStylePlayerControls: Mimics MPMoviePlayer controls.
   • blurStyleBar: Mimics UINavigationBar, UIToolbar, UITabBar.
   • blurStyleCustom: Defaults to filters that essentially do nothing, you will be responsible for configuring the CAFilters yourself.

You can treat JMIBlurView as any other view at this point. You can animate moving it around, and even apply a background color.

##How does it work?

According to this post on the Apple developer forums, Apple is achieving this effect using a private UIView subclass, which employs the private CAFilter class to blur whatever it's obscuring in near-real time. Essentially, I swizzled and logged the crap out of CAFilter to see exactly what filters they were creating and how they were configuring them. Once I had that info, it was relatively easy to figure out how to apply them to a view.

There are 3 filters created per view:

• Gaussian Blur: This is the bread and butter of the blur effect. It's might even be why it's called a blur effect. It's pretty blurry.
• Color Saturate: This helps create that color bleeding effect that gives the effect more of a frosted glass effect.
• Color Matrix: This filter I'm not so clear about. It appears to be a combination of a contrast filter and a brightness filter. The values used by MPMoviePlayer views and UINavigation/Tool/Tab bars are very different.

##Remaining Questions

What exactly is that third filter do? Will Apple finally let us use CAFilters? The class has been around since iOS 2.0, after all.

##Performance

Performance in the simulator is not great, especially when moving the blur view, but performance on device is actually quite nice.