A hacked together blur view

CYBackdropView.h

#import <UIKit/UIKit.h>

@interface CYBackdropView : UIView
@property(nonatomic) UIColor *blurColor;
@property(nonatomic) float blurStrength;
@end

CYBackdropView.mm

#import "CYBackdropView.h"

@interface CYBackdropView () {
    UINavigationBar *_navBar;
    UIView *_colorView;
}
@end

@implementation CYBackdropView

- (void)_init
{
    self.clipsToBounds = YES;
    _navBar = [[UINavigationBar alloc] initWithFrame:CGRectInset(self.bounds, 0, -1)];
    _navBar.autoresizingMask = UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth;
    _navBar.translucent = YES;
    [self addSubview:_navBar];
    
    _colorView = [[UIView alloc] initWithFrame:CGRectInset(self.bounds, 0, -1)];
    _colorView.autoresizingMask = UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth;
    [self addSubview:_navBar];

    self.blurColor = [UIColor redColor];
    self.blurStrength = 0.8;
}

- (id)initWithFrame:(CGRect const)aFrame
{
    if((self = [super initWithFrame:aFrame]))
        [self _init];

    return self;
}

- (id)initWithCoder:(NSCoder * const)aDecoder
{
    if((self = [super initWithCoder:aDecoder]))
        [self _init];
    return self;
}

- (UIColor *)blurColor
{
    return _navBar.barTintColor;
}

- (void)setBlurColor:(UIColor *)aColor
{
    _colorView.backgroundColor = aColor;
    _navBar.barTintColor = aColor;
}

- (float)blurStrength
{
    return _navBar.alpha;
}

- (void)setBlurStrength:(float const)aStrength
{
    float const strength = 0.9f + aStrength/10.0f;
    
    _navBar.alpha    = strength;
    _colorView.alpha = (1.0f - strength) / 2.0f;
}

@end