Where should I store 30+ UIColors for quick refere

问题:

I want to have 30+ constant UIColors so I can easily access them in my app. I'd like to be able to do something like this:

 [self setBackgroundColor:[UIColor skyColor]];
 [self setBackgroundColor:[UIColor dirtColor]];
 [self setBackgroundColor:[UIColor yankeesColor]];

How can I do this?

Thanks!!

回答1:

Define a category for UIColor:

In UIColor+MyColors.h:

@interface UIColor (MyColors)

+ (UIColor *)skyColor;
+ (UIColor *)dirtColor;
// and the rest of them

@end

In UIColor+MyColors.m:

@implementation UIColor (MyColors)

+ (UIColor *)skyColor {
    static UIColor color = nil;
    if (!color) {
        // replace r, g, and b with the proper values
        color = [UIColor colorWithRed:r green:g blue:b alpha:1];
    }

    return color;
}

+ (UIColor *)dirtColor {
    static UIColor color = nil;
    if (!color) {
        // replace r, g, and b with the proper values
        color = [UIColor colorWithRed:r green:g blue:b alpha:1];
    }

    return color;
}

// and the rest

@end

Edit:

As Martin R points out, a more modern approach to initializing the static color variable would be:

+ (UIColor *)skyColor {
    static UIColor color = nil;
    static dispatch_once_t predicate = 0;

    dispatch_once(&predicate, ^{
        // replace r, g, and b with the proper values
        color = [UIColor colorWithRed:r green:g blue:b alpha:1];
    });

    return color;
}

This may actually be overkill in this case since there is no bad side-effect if two threads happen to initialize the nil static variable at the same time using the original code. But it is a better habit to use dispatch_once.

回答2:

You can add lines like this:

#define kFirstColor [UIColor whiteColor]
#define kSecondColor [UIColor colorWithRed:100.0/255 green:100.0/255 blue:100.0/255 alpha:1.0]

At the beginning of a class or add a Color.h header to your project and import it when needed.

#import "Color.h"

Then you can use your custom colors this way:

self.view.backgroundColor = kSecondColor;