Store UIColor in Array

Question

I have a UIColor created by [UIColor colorWithPatternImage:...]; and I want to store it in an NSArray.

I have a problem, however, as I have the following code for normal colors

NSString *NSStringFromUIColor(UIColor *color) {
    //Creates a string with RGB values of the color
    const CGFloat *components = CGColorGetComponents(color.CGColor);
    return [NSString stringWithFormat:@"[%f, %f, %f, %f]",
            components[0],
            components[1],
            components[2],
            components[3]];
}

But the above crashes with my unconventional patternColorFromImage. So once again, how do I store this color in an NSArray etc?

Thanks

score 4 · Accepted Answer · edited May 23 '17 at 12:33

NSArray works with Objective-C objects, which the "(float)" cast I see up there most definitely is not.

To be more specific, "float", "int", "char" are C data types, CGFloat is a Core Graphics data structure (and also not an Objective C object).

If you want to save colors in an array, they need to be true "UIColor" Objective-C objects.

If you want to save your CGFloats in a NSArray, you can do the answer in this related question.

score 0 · Answer 2 · answered Jan 06 '14 at 15:48

If you want to save parameterized colors in an array, wrap the values in NSNumbers (though, UIColor seems like a better alternative). In other words, either

CGFloat red = 0.5;
NSArray *colorParams = @[ [NSNumber numberWithFloat:red], // etc

or, better:

NSArray *color = [UIColor colorWithRed:red // etc

Either of these objects can be placed in another array:

NSArray *myArrayOfColors = @[ colorParams, color, // but watch out, we have two distinct
// representations of colors in this array

score 0 · Answer 3 · answered Jan 06 '14 at 15:56

You can't store C types into an NSArray. You could do this:

[NSArray arrayWithObjects: [NSNumber numberWithDouble: components[0]], [NSNumber numberWithDouble: components[1]], nil];

If there in fact are only two components. Here's a more generic version:

CGColorRef cgColor = [myColor CGColor];
NSUInteger numComponents = CGColorGetNumberOfComponents(cgColor);
CGFloat const *components = CGColorGetComponents(cgColor);
NSNumber *componentObjects[numComponents];
for (NSUInteger i = 0; i < numComponents; i++)
    componentObjects[i] = [NSNumber numberWithDouble: components[i]];
NSArray *colorArray = [NSArray arrayWithObjects: componentObjects count: numComponents];

score 0 · Answer 4 · answered Jan 06 '14 at 19:54

0

NSString* NSStringFromColor(UIColor* color) {
    CGFloat r, g, b, a;
    [color getRed:&r green:&g blue:&b alpha:&a];
    return [NSString stringWithFormat:@"[%f, %f, %f, %f"], r, g, b, a];
}

answered Jan 06 '14 at 19:54

apexwill

21
3

score -1 · Answer 5 · answered Jan 06 '14 at 16:19

In the expression [UIColor redColor], it is obvious to see that redColor is a selector. Also, we can convert selectors to NSStrings and vice-versa with:

NSString colorSel = NSStringFromSelector(@selector(redColor));
SEL redSel = NSSelectorFromString(colorSel");

I'm on a windows PC right now so cannot say for sure whether it should be enclosed in @selector() or not. But you can try them both out to see which one is the right way.

One you get the selector from string, you can set color with:

if ([UIColor respondsToSelector:redSel])
    yourElement.backgroundColor = [UIColor performSelector:redSel];

This is a basic example with basic UIColors. You can use UIColorFromRGB macros, or CGColors too.

Once you get an NSString with your color, you can easily store them in an array.

Store UIColor in Array

5 Answers5