일반적인 코드
self.view.backgroundColor =
[UIColor colorWithRed:123/255.0 green:123/255.0 blue:123/255.0 alpha:1];============================================================
#define 이용하여 개선 된 코드
#define RGB(r, g, b)
[UIColor colorWithRed:r/255.0 green:g/255.0 blue:b/255.0 alpha:1]
#define RGBA(r, g, b, a)
[UIColor colorWithRed:r/255.0 green:g/255.0 blue:b/255.0 alpha:a]
self.view.backgroundColor = RGB(123, 123, 123);
