How to Create Several Cached Uicolor

How to create several cached UIColor

You can use the same approach as in
Using a dispatch_once singleton model in Swift, i.e. static
constant stored properties
which are initialized lazily (and only once). These can be defined
directly in the UIColor extension:

extension UIColor {
    convenience init(hex: String) {
        // ...          
    }

    static let myColorOne = UIColor(hex:"AABBCC")
    static let myColorTwo = UIColor(hex:"DDEEFF")
}

Best practice for creating many UIColors?

First you should profile with Instruments to see if a considerable amount of time is spent in these calls. If this is the case, then make them static variables and initialize them on first use:

-(void)drawRect:(CGRect)rect
{
    static UIColor *bgColor;
    static UIColor *textColor;
    static UIColor *strokeColor;

    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        bgColor = [UIColor colorWithWhite:0.9 alpha:1.0];
        textColor = [UIColor colorWithWhite:0.98 alpha:1.0];
        strokeColor = [UIColor colorWithWhite:0.6 alpha:1.0];
    });

    /* use colors */
}

Extension for UIColor with custom colors it is real?

Create class property in UIColor extension

extension UIColor
{
  class var themeColor:UIColor {
    return UIColor(red: 210.0/255.0, green: 105.0/255.0, blue: 130.0/255.0, alpha: 1.0)
  }
}

OR

extension UIColor {
  static let themeColor = UIColor(red: 210.0/255.0, green: 105.0/255.0, blue: 130.0/255.0, alpha: 1.0)
}

Usage

self.view.backgroundColor = UIColor.themeColor

How to define my own custom UIColor?

Try something like this:

extension UIColor {

    static let myCustomColor = UIColor(red: 1, green: 1, blue: 1, alpha: 1)

}

How to Convert a string into a UIColor (Swift)

UIColor named: only works when you define a color set asset. Since your colors are defined in code, UIColor named: will never return anything but nil.

One solution is to put your colors into a dictionary instead of separate variables.

let colors: [String: UIColor] = [
    "color1" : UIColor(red: 1, green: 153/255, blue: 0, alpha: 1),
    "color2" : UIColor(red: 74/255, green: 134/255, blue: 232/255, alpha: 1),
    "color3" : UIColor(red: 0, green: 0, blue: 1, alpha: 1),
    "color4" : UIColor(red: 0, green: 1, blue: 0, alpha: 1),
    "color5" : UIColor(red: 153/255, green: 0, blue: 1, alpha: 1),
    "color6" : UIColor(red: 1, green: 0, blue: 0 , alpha: 1),
]

Then you can get your color as:

tile.color = colors["color\(value)"] ?? colors["color1"]!

Use Same Variable In Multiple View Controllers

One approach here is to create an extension on UIColor. You can then make them global to your module.

extension UIColor {
    static var myRed: UIColor {
        return UIColor(red:0.61, green:0.12, blue:0.20, alpha:1.0)
    }
    static var myBlue: UIColor {
        return UIColor(red: 0.08, green: 0.49, blue: 0.49, alpha:1.0)
    }
}

What is the UIColor of the default UITableView separator?

… in terms of CGContextSetRGBStrokeColor it should be:

CGContextSetRGBStrokeColor (
   CGContextRef c,
   224.0/255.0,
   224.0/255.0,
   224.0/255.0,
   CGFloat alpha
);

Quite simple and hopefully a solution for your problem.

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