How can I create a UIColor that can be accessed anywhere in my project?

[kjmcneish]

Often, apps use a custom background color throughout the app to help brand the app. If you want to declare a custom color that can be accessed from anywhere within your app, you can create an Objective-C category that extends the UIColor class (see Book 2: Flying With Objective-C, Chapter 16: Advanced Objective-C under the section Extending Classes with Categories for more info):


1. Create a new category based on UIColor. For example, here is the .h file:

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#import <UIKit/UIKit.h>

@interface UIColor (BurgundyColor)

+ (UIColor*)burgundyColor;

@end
And here is the .m file:

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#import "UIColor+BurgundyColor.h"

@implementation UIColor (BurgundyColor)

+ (UIColor*)burgundyColor {
   
    return [UIColor colorWithRed:180.0/255.0 green:20.0/255.0 blue:30.0/255.0 alpha:1];
}

@end
2. Add a reference to the new category in your project's .pch file (located under the Supporting Files group). For example:

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#ifdef __OBJC__
    #import <UIKit/UIKit.h>
    #import <Foundation/Foundation.h>
    #import <CoreData/CoreData.h>
    #import "UIColor+BurgundyColor.h"
#endif
3. Now you can reference the new color from anywhere in your project. For example:

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[[UINavigationBar appearance] setBarTintColor:[UIColor burgundyColor]];
All the best!
Kevin McNeish
Author of "Learn to Code in Swift": https://itunes.apple.com/us/book/learn-to-code-in-swift/id942956811?mt=11