Problem in passing UIColor preset value

I have follo开发者_开发问答wing components - ColorButton, that represents single button that is basically colored rectangle, and PaletteView, that is grid of ColorButton objects.

The code looks something like this:

ColorButton.h

@interface ColorButton : UIButton {
    UIColor* color;
}

-(id) initWithFrame:(CGRect)frame andColor:(UIColor*)color;

@property (nonatomic, retain) UIColor* color;

@end

ColorButton.m

@implementation ColorButton

@synthesize color;

- (id)initWithFrame:(CGRect)frame andColor:(UIColor*)aColor{    
    self = [super initWithFrame:frame];
    if (self) {
        self.color = aColor;
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
    CGContextRef context = UIGraphicsGetCurrentContext();
    const float* colors = CGColorGetComponents(color.CGColor);
    CGContextSetRGBFillColor(context, colors[0], colors[1], colors[2], colors[3]);
    CGContextFillRect(context, rect);
}

PaletteView.m

- (void) initPalette {        
    ColorButton* cb = [[ColorButton alloc] initWithFrame:CGRectMake(0, 0, 30, 30) andColor:[UIColor grayColor]];
    [self addSubview:cb];    
}

The problem is that it does not work - nothing is drawing in view. However, following code works.

PaletteView.m

- (void) initPalette {    
    UIColor *color = [[UIColor alloc]
                      initWithRed: (float) (100/255.0f)
                      green: (float) (100/255.0f)
                      blue:  (float) (1/255.0f)
                      alpha: 1.0];

    ColorButton* cb = [[ColorButton alloc] initWithFrame:CGRectMake(0, 0, 30, 30) andColor:color];
    [self addSubview:cb];
}

In this case I pass not autoreleased UIColor object, in comparison to [UIColor grayColor] - autoreleased object.

Also following code works:

ColorButton.m

- (id)initWithFrame:(CGRect)frame andColor:(UIColor*)aColor{    
    self = [super initWithFrame:frame];
    if (self) {
        //self.color = aColor;
        self.color = [UIColor redColor];
    }
    return self;
}

Can someone explain what is going on here, why I cannot pass objects like [UIColor grayColor] ? And what is correct way to solve my task - pass color values from PaletteView to ColorButton ?

Thanks!

---

The problem is that you're asking for the color components for the CGColor with CGColorGetComponents. This method might return a different number of components, depending on the color space of the underlying color object. For example, [UIColor grayColor] is probably in a grayscale color space, and so is only setting colors[0].

If you want to set the fill color for a context, you can use CGContextSetFillColorWithColor which take the CGColorRef object directly, so you don't need to use the components at all.