CODEWITHSUNDEEP
objective-ccomponentsuicolor
L. Kvri
L. Kvri

Reputation: 1733

get components of color in objective-c

Here is a code snippets for get RGB components of color. What can I do if the _countComponents is less than four, for example two? I tried to get components of color gray [UIColor grayColor]

int _countComponents = CGColorGetNumberOfComponents(colorRef);

if (_countComponents == 4) {
    const CGFloat *_components = CGColorGetComponents(colorRef);
    CGFloat red     = _components[0];
    CGFloat green = _components[1];
    CGFloat blue   = _components[2];
    CGFloat alpha = _components[3];

Upvotes: 2

Views: 1285

Answers (3)

Peter M
Peter M

Reputation: 7493

New Answer

After re-reading the question. To answer the Gray components question, the way you read that is via -(BOOL)getWhite:alpha:

So you would do as per Caleb with something like:

BOOL success = [myColor getWhite:&w alpha:&a];

This gives you the gray value w as 0 to 1 and the alpha value a as 0 to 1

See the Apple docs getWhite:alpha:

Old answer

From this SO question how-to-access-the-color-components-of-an-uicolor

See the (rather old) ArsTechnica artical iphone-development-accessing-uicolor-components

Upvotes: 1

Caleb
Caleb

Reputation: 125007

If you've got an instance of UIColor and you want it's RGB values, why not use the -getRed:green:blue:alpha: method?

CGFloat r, g, b, a;
BOOL success = [myColor getRed:&r green:&g blue:&b alpha:&a];
if (success) {
    // the color was converted to RGB successfully, go ahead and use r,g,b, and a.
}

Upvotes: 6

sch
sch

Reputation: 27506

The components of a color depend on the associated color space.

So _components[0], _components[1], etc are not necessary red, green blue and alpha.

Upvotes: 1

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