Less Blur with `Visual Effect View with Blur`?

Question

Title pretty much asks it all...

I'm playing with the iOS8 Visual Effect View with Blur. It's over a UIImageView that shows a user choosable background photo. The view placed in the contentView itself is my own custom view, shows a sort of graph/calendar. Most of said calendar graph is transparent. The blur it applies to the photo behind it is really heavy. I'd like to let more of the detail leak through. But Apple only seems to give three canned values:

typedef enum {     UIBlurEffectStyleExtraLight,     UIBlurEffectStyleLight,     UIBlurEffectStyleDark  } UIBlurEffectStyle; 

I've monkied around with different alphas and background colors of the UIVisualEffectView (even though the documentation warns against that), but that doesn't do anything but make it worse.

Answer 1

The reason you're getting heavy blur is that the blur effect style affects the brightness level of the image, not the amount of blur applied.

Unfortunately, although Apple clearly has the ability to control the amount of blur applied programmatically--try dragging down slowly on the launchpad to watch the Spotlight blurring transition--I don't see any public API to pass a blur amount to UIBlurEffect.

This post claims that adjusting the background color alpha will drive the blur amount. It's worth a try, but I don't see where that is documented: How to fade a UIVisualEffectView and/or UIBlurEffect in and out?

Answer 2

It's a pity that Apple did not provide any options for blur effect. But this workaround worked for me - animating the blur effect and pausing it before completion.

func blurEffectView(enable enable: Bool) {     let enabled = self.blurView.effect != nil     guard enable != enabled else { return }      switch enable {     case true:         let blurEffect = UIBlurEffect(style: .ExtraLight)         UIView.animateWithDuration(1.5) {             self.blurView.effect = blurEffect         }          self.blurView.pauseAnimation(delay: 0.3)     case false:         self.blurView.resumeAnimation()          UIView.animateWithDuration(0.1) {             self.blurView.effect = nil         }     } } 

and the UIView extensions for pausing (with a delay) and resuming view's animation

extension UIView {      public func pauseAnimation(delay delay: Double) {         let time = delay + CFAbsoluteTimeGetCurrent()         let timer = CFRunLoopTimerCreateWithHandler(kCFAllocatorDefault, time, 0, 0, 0, { timer in             let layer = self.layer             let pausedTime = layer.convertTime(CACurrentMediaTime(), fromLayer: nil)             layer.speed = 0.0             layer.timeOffset = pausedTime         })         CFRunLoopAddTimer(CFRunLoopGetCurrent(), timer, kCFRunLoopCommonModes)     }      public func resumeAnimation() {         let pausedTime  = layer.timeOffset          layer.speed = 1.0         layer.timeOffset = 0.0         layer.beginTime = layer.convertTime(CACurrentMediaTime(), fromLayer: nil) - pausedTime     } }