OC: 宏定义, 例子
对的
#define RGBAlpha(r, g, b, a) [[UIColor colorWithRed:(r) / 255.0 green:(g) / 255.0 blue:(b) / 255.0 alpha:(a) ] set]
RGBAlpha(85, 26, 19, 0.5);
错的
#define RGBAlphaWrong(r, g, b, alpha) [[UIColor colorWithRed:(r) / 255.0 green:(g) / 255.0 blue:(b) / 255.0 alpha:(alpha) ] set]
RGBAlphaWrong(85, 26, 19, 0.5); // Messg: Expected ']'
