tvOS 10 Dark Mode Helper

UITraitCollection+DarknessCompatibility.m

//
//  UITraitCollection+DarknessCompatibility.h
//  Tangent
//
//  Created by Tim Johnsen on 6/25/16.
//  Copyright © 2016 tijo. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UITraitCollection (DarknessCompatibility)

- (BOOL)tj_isDark;
- (BOOL)tj_hasSameDarkSettingAs:(UITraitCollection *const)traitCollection;

@end

//
//  UITraitCollection+DarknessCompatibility.m
//  Tangent
//
//  Created by Tim Johnsen on 6/25/16.
//  Copyright © 2016 tijo. All rights reserved.
//

#import "UITraitCollection+DarknessCompatibility.h"

@implementation UITraitCollection (DarknessCompatibility)

- (BOOL)tj_isDark
{
    BOOL isDark = NO;
    // TODO: Use actual selector and enum value once building for iOS 10.
    static BOOL isTvOS1OrHigher = NO;
    static SEL userInterfaceStyleSelector = nil;
    static NSInvocation *userInterfaceStyleInvocation = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){10, 0, 0}]) {
            isTvOS1OrHigher = YES;
            
            userInterfaceStyleSelector = NSSelectorFromString(@"userInterfaceStyle");
            userInterfaceStyleInvocation = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:userInterfaceStyleSelector]];
            userInterfaceStyleInvocation.selector = userInterfaceStyleSelector;
        }
    });
    if (isTvOS1OrHigher) {
        [userInterfaceStyleInvocation invokeWithTarget:self];
        NSInteger returnValue = 0;
        [userInterfaceStyleInvocation getReturnValue:&returnValue];
        static const NSInteger tj_UIUserInterfaceStyleDark = 2;
        isDark = (returnValue == tj_UIUserInterfaceStyleDark);
    }
    return isDark;
}

- (BOOL)tj_hasSameDarkSettingAs:(UITraitCollection *const)traitCollection
{
    return [self tj_isDark] == [traitCollection tj_isDark];
}

@end