FLEX/Classes/Utility/FLEXColor.m

//
//  FLEXColor.m
//  FLEX
//
//  Created by Benny Wong on 6/18/19.
//  Copyright © 2019 Flipboard. All rights reserved.
//

#import "FLEXColor.h"
#import "FLEXUtility.h"

#if FLEX_AT_LEAST_IOS13_SDK
#define FLEXDynamicColor(dynamic, static) ({ \
    UIColor *c; \
    if (@available(iOS 13, *)) { \
        c = [UIColor dynamic]; \
    } else { \
        c = [UIColor static]; \
    } \
    c; \
});
#else
#define FLEXDynamicColor(dynamic, static) [UIColor static]
#endif

@implementation FLEXColor

#pragma mark - Background Colors

+ (UIColor *)primaryBackgroundColor {
    return FLEXDynamicColor(systemBackgroundColor, whiteColor);
}

+ (UIColor *)primaryBackgroundColorWithAlpha:(CGFloat)alpha {
    return [[self primaryBackgroundColor] colorWithAlphaComponent:alpha];
}

+ (UIColor *)secondaryBackgroundColor {
    return FLEXDynamicColor(
        secondarySystemBackgroundColor,
        colorWithHue:2.0/3.0 saturation:0.02 brightness:0.95 alpha:1
    );
}

+ (UIColor *)secondaryBackgroundColorWithAlpha:(CGFloat)alpha {
    return [[self secondaryBackgroundColor] colorWithAlphaComponent:alpha];
}

+ (UIColor *)tertiaryBackgroundColor {
    // All the background/fill colors are varying shades
    // of white and black with really low alpha levels.
    // We use systemGray4Color instead to avoid alpha issues.
    return FLEXDynamicColor(systemGray4Color, lightGrayColor);
}

+ (UIColor *)tertiaryBackgroundColorWithAlpha:(CGFloat)alpha {
    return [[self tertiaryBackgroundColor] colorWithAlphaComponent:alpha];
}

#pragma mark - Text colors

+ (UIColor *)primaryTextColor {
    return FLEXDynamicColor(labelColor, blackColor);
}

+ (UIColor *)deemphasizedTextColor {
    return FLEXDynamicColor(tertiaryLabelColor, lightGrayColor);
}

#pragma mark - UI Element Colors

+ (UIColor *)scrollViewBackgroundColor {
    return FLEXDynamicColor(
        systemGroupedBackgroundColor,
        colorWithHue:2.0/3.0 saturation:0.02 brightness:0.95 alpha:1
    );
}

+ (UIColor *)iconColor {
    return FLEXDynamicColor(labelColor, blackColor);
}

+ (UIColor *)borderColor {
    return [self primaryBackgroundColor];
}

+ (UIColor *)toolbarItemHighlightedColor {
    return FLEXDynamicColor(
        quaternaryLabelColor,
        colorWithHue:2.0/3.0 saturation:0.1 brightness:0.25 alpha:0.6
    );
}

+ (UIColor *)toolbarItemSelectedColor {
    return FLEXDynamicColor(
        secondaryLabelColor,
        colorWithHue:2.0/3.0 saturation:0.1 brightness:0.25 alpha:0.68
    );
}

@end