xcode 在项目中全局声明 UIColor
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Globally declare UIColor in project
提问by Sohan
Possible Duplicate:
Objective C defining UIColor constants
I'd like to use few colours throughout my app. Instead of creating a UIColor at every instance or in every viewController is there a way by which i can use it throughout the app.
我想在整个应用程序中使用几种颜色。有一种方法可以让我在整个应用程序中使用它，而不是在每个实例或每个 viewController 中创建 UIColor。
or is it wise to use a ColourConstants.h header file where i #define each colour i want to use
或者使用 ColourConstants.h 头文件是明智的，我在其中 #define 我想使用的每种颜色
i.e
IE
#define SCARLET [UIColor colorWithRed:207.0/255.0 green:47.0/255.0 blue:40.0/255.0 alpha:1];
thanks in advance!
提前致谢！
回答by Garoal
I would use a category on UIColor. For example:
我会在 UIColor 上使用一个类别。例如：
// In UIColor+ScarletColor.h
@interface UIColor (ScarletColor)
+ (UIColor*)scarletColor;
@end
// In UIColor+ScarletColor.m
@implementation UIColor (ScarletColor)
+ (UIColor*)scarletColor {
return [UIColor colorWithRed:207.0/255.0 green:47.0/255.0 blue:40.0/255.0 alpha:1];
}
@end
And when you want to use the color you only have to do this:
当你想使用颜色时，你只需要这样做：
#import "UIColor+ScarletColor.h"
....
UIColor *scarlet = [UIColor scarletColor];
Hope it helps!!
希望能帮助到你！！
回答by Macmade
A macro is more convenient, as it's defined only in one place.
宏更方便，因为它只在一个地方定义。
But it will still create a new instance, every time it's used, as a macro is just text replacement for the pre-processor.
但它仍然会在每次使用时创建一个新实例，因为宏只是预处理器的文本替换。
If you want to have a unique instance, you'll have to use FOUNDATION_EXPORT(which means extern).
如果您想拥有一个唯一的实例，则必须使用FOUNDATION_EXPORT（这意味着extern）。
In a public .h file, declares the following:
在公共 .h 文件中，声明以下内容：
FOUNDATION_EXPORT UIColor * scarlet;
This will tell the compiler that the scarletvariable (of type UIColor) will exist at some point (when the program is linked).
So it will allow you to use it.
这将告诉编译器scarlet变量（类型UIColor）将在某个时刻（当程序链接时）存在。
所以它会让你使用它。
Then you need to create that variable, in a .m file.
You can't assign its value directly, as it's a runtime value, so just set it to nil:
然后您需要在 .m 文件中创建该变量。
您不能直接分配它的值，因为它是一个运行时值，因此只需将其设置为 nil：
UIColor * scarlet = nil;
And then, at some point in your program (maybe in your app's delegate), set its value:
然后，在您的程序中的某个点（可能在您的应用程序的委托中），设置其值：
scarlet = [ [ UIColor ... ] retain ];
Do not forget to retain it, as it's a global variable which needs to live during the entire life-time of the program.
不要忘记保留它，因为它是一个全局变量，需要在程序的整个生命周期中都存在。
This way, you have only one instance, accessible from everywhere.
这样，您只有一个实例，可以从任何地方访问。
