UIBackdropView

_UIBackdropView is a private class in UIKit.framework (iOS 7.0+), a subclass of UIView, which is used for the popular blur effects.

It uses a CABackdropLayer with a gaussianBlur CAFilter.

Creating Settings

_UIBackdropView uses a _UIBackdropViewSettings object for its setup. There are many ways to create it:

_UIBackdropViewSettings *settings = (_UIBackdropViewSettings *)[[[_UIBackdropViewSettingsSemiLight alloc] init] autorelease];

_UIBackdropViewSettings *settings = [_UIBackdropViewSettings settingsForStyle:2070];

_UIBackdropViewSettings *settings = [_UIBackdropViewSettings settingsForPrivateStyle:2070];

_UIBackdropViewSettings *settings = [[[_UIBackdropViewSettings alloc] initWithDefaultsValue] autorelease];

Here's a list with known settings classes (subclasses of _UIBackdropViewSettings) available in iOS 7.

Class name	Style number(s)	Comments/Used by
_UIBackdropViewSettingsCombiner	-3
_UIBackdropViewSettingsNone	-2
_UIBackdropViewSettingsLight	0, 1000, 1003, 2020, 10090, 10100
_UIBackdropViewSettingsDark	1, 1001, 1100, 2030, 11050, 11060	iOS 7 Notification Center (?), keyboard, Safari NavigationBar
_UIBackdropViewSettingsBlur	2	Common blurring
_UIBackdropViewSettingsColorSample	2000
_UIBackdropViewSettingsUltraLight	2010	Some alert views in Settings app & many white UIs
_UIBackdropViewSettingsLightLow	2029
_UIBackdropViewSettingsDarkWithZoom	2031
_UIBackdropViewSettingsDarkLow	2039
_UIBackdropViewSettingsColored	2040	rgba(0.0196078,0.0196078,0.0196078,1)
	10091	rgba(0.160784,1,0.301961,1)
	10092	rgba(1,0.0980392,0.0470588,1)
	10120	rgba(0.0313725,0.262745,0.560784,1)
_UIBackdropViewSettingsUltraDark	2050, 11070
_UIBackdropViewSettingsAdaptiveLight	2060	iOS 7 Control Center
_UIBackdropViewSettingsSemiLight	2070
_UIBackdropViewSettingsFlatSemiLight	2071
_UIBackdropViewSettingsUltraColored	2080
_UIBackdropViewSettingsPasscodePaddle	3900	iOS 7.1+
_UIBackdropViewSettingsLightKeyboard	3901	iOS 7.1+

Creating Sample

// Creating blur view using settings object
_UIBackdropViewSettings *settings = [_UIBackdropViewSettings settingsForStyle:2060];

// initialization of the blur view
_UIBackdropView *blurView = [[_UIBackdropView alloc] initWithFrame:CGRectZero
                                              autosizesToFitSuperview:YES settings:settings];
// another way for initialization
_UIBackdropView *blurView = [[_UIBackdropView alloc] initWithSettings:settings];

// or without settings object implementation
_UIBackdropView *blurView = [[_UIBackdropView alloc] initWithStyle:2060];

[someView addSubview:backView];
[blurView release];

Blurring Sample

There are only two blur qualities available.

• low
• default (Assumed to be "medium")

[blurView setBlurRadiusSetOnce:NO];
[blurView setBlurRadius:10.0];
[blurView setBlurHardEdges:3];
[blurView setBlurWithHardEdges:YES];
[blurView setBlurQuality:@"low"];

Tinting Sample

[blurView setRequiresColorStatistics:YES];
[blurView setUsesColorTintView:YES];
UIColor *color = [UIColor cyanColor];
[blurView setColorTint:color]; // or you may use - (void)transitionToColor:(UIColor *)color;
[blurView setColorTintAlpha:0.8];
[blurView setColorTintMaskAlpha:0.7];

Applying blur settings/style

There are several ways for doing this by methods.

Signature	- (void)transitionIncrementallyToPrivateStyle:(int)style weighting:(float)weight;
Available in	7.0 –

Signature	- (void)transitionIncrementallyToStyle:(int)style weighting:(float)weight;
Available in	7.0 –

Signature	- (void)transitionToSettings:(_UIBackdropViewSettings *)settings;
Available in	7.0 –

Signature	- (void)transitionToPrivateStyle:(int)style;
Available in	7.0 –

Signature	- (void)transitionToStyle:(int)style;
Available in	7.0 –

For example

_UIBackdropViewSettings *newSettings = [_UIBackdropViewSettings settingsForPrivateStyle:0];

// Whatever configuration for the settings

[blurView setInputSettings:newSettings];

Getting/Parsing all _UIBackdropView objects at runtime

NSArray *blurViews = [_UIBackdropView allBackdropViews];

for (_UIBackdropView *view in blurViews) {
      NSLog(@"This _UIBackdropView style is: %d", view.style);
     // do any _UIBackdropView configuration here
}