How can I detect if an iOS device supports the blur effect?

Question

It appears that different iOS devices render UINavigationBars with barStyle = UIBarStyleBlack and translucent = YES very differently. Consider:

iPhone 4, no tint:

iPhone 5, no tint:

iPhone 4, barTintColor = [UIColor colorWithWhite:0.0f alpha:0.5f]:

iPhone 5, barTintColor = [UIColor colorWithWhite:0.0f alpha:0.5f]:

The iPhone 5 produces the desired effect without a tint, but the 4 is opaque. Adding a semitransparent tint makes the 4 look good, but screws up the 5.

The same holds true for the iPad 2 and 3, and theoretically any device that does not support the iOS 7 blur effects.

Short of blacklisting these older devices, how can I detect if a device supports the blurring so that I can conditionally work around the rendering differences? Or is there a way to normalize the appearance without using a tint at all?

Answer 1

What about this UIDevice category along with observing for UIAccessibilityReduceTransparencyStatusDidChangeNotification?

@interface UIDevice (Additions)

@property (readonly) NSString *platform;
@property (readonly) BOOL canBlur;

@end


@implementation UIDevice (Additions)

- (NSString *)platform {
    int mib[] = { CTL_HW, HW_MACHINE };
    size_t len = 0;
    sysctl(mib, 2, NULL, &len, NULL, 0);
    char *machine = malloc(len);
    sysctl(mib, 2, machine, &len, NULL, 0);
    NSString *platform = [NSString stringWithCString:machine encoding:NSASCIIStringEncoding];
    free(machine);

    return platform;
}

- (BOOL)canBlur {
    if(NSStringFromClass([UIVisualEffectView class]) && UIDevice.currentDevice.systemVersion.floatValue >= 8.0 && !UIAccessibilityIsReduceTransparencyEnabled()) {
        NSString *platform = self.platform;
        CGFloat deviceVersion = [[[platform stringByReplacingOccurrencesOfString:@"[^0-9,.]" withString:@"" options:NSRegularExpressionSearch range:NSMakeRange(0, platform.length)] stringByReplacingOccurrencesOfString:@"," withString:@"."] floatValue];

        if([platform isEqualToString:@"i386"] || [platform isEqualToString:@"x86_64"]) {
            return YES;
        } else if([platform rangeOfString:@"iPhone"].location != NSNotFound) {
            return (deviceVersion >= 4.1);
        } else if([platform rangeOfString:@"iPod"].location != NSNotFound) {
            return (deviceVersion >= 5.1);
        } else if([platform rangeOfString:@"iPad"].location != NSNotFound) {
            return (deviceVersion >= 3.4);
        }
    }

    return NO;
}

Don't forget to #include in your implementation file.