Color Variables in Objective C

Question

How do I set and reuse a color variable in Obj C? I am trying to set a reusable color value as in this question:

Change background color with a variable iOS

but am unsuccessful.

 UIColor *lightGrayHeader = [UIColor colorWithRed:246/255.f green:239/255.f blue:239/255.f alpha:1.0];

 self.view.backgroundColor = [UIColor lightGrayHeader];

Returns an error: "Initializer element is not a compile-time constant."

Thanks for your ideas!

Answer 1

What you have defined is a local variable. It is used like this:

UIColor *lightGrayHeader = [UIColor colorWithRed:246/255.f green:239/255.f blue:239/255.f alpha:1.0];
self.view.backgroundColor = lightGrayHeader;

If you want to use a static method on UIColor to fetch a colour, you could do this:

@interface UIColor (MyColours)
+ (instancetype)lightGrayHeader;
@end

@implementation UIColor (MyColours)
+ (instancetype)lightGrayHeader {
  return [self  colorWithRed:246/255.f green:239/255.f blue:239/255.f alpha:1.0];
}
@end

And then as long as you import the UIColor (MyColours) header, you could use:

self.view.backgroundColor = [UIColor lightGrayHeader];

Answer 2

Since you've already created the lightGrayHeader color, just use it:

UIColor *lightGrayHeader = [UIColor colorWithRed:246/255.f green:239/255.f blue:239/255.f alpha:1.0];
self.view.backgroundColor = lightGrayHeader;
self.otherView.backgroundColor = lightGrayHeader;
...

Answer 3

UIColor *lightGrayHeader = [UIColor colorWithRed:246/255.f green:239/255.f blue:239/255.f alpha:1.0];
self.view.backgroundColor = [UIColor lightGrayHeader]; // error

It's a variable, not a method of UIColor:

self.view.backgroundColor = lightGrayHeader;

Answer 4

It works like this self.view.backgroundColor = lightGrayHeader;