Objective-C Method Parameters Problem
objective-c, parameters, primitive
Solution
Define a `struct` that contains all of the components, or wrap up each individual component in an `NSNumber`. Alternatively, use an `NSColor` instance to contain your colour components.
`struct` way:
typedef struct
{
float red;
float green;
float blue;
float alpha;
} MyColor;
- (MyColor) percentagesRGBArray:(MyColor) incoming
{
MyColor result;
result.red = incoming.red / 255;
result.green = incoming.green / 255;
result.blue = incoming.blue / 255;
result.alpha = incoming.alpha;
return result;
}
`NSNumber` way:
- (NSArray *) percentagesRGBArray:(float[]) rgbArray
{
NSNumber *red = [NSNumber numberWithFloat:rgbArray[0] / 255];
NSNumber *green = [NSNumber numberWithFloat:rgbArray[1] / 255];
NSNumber *blue = [NSNumber numberWithFloat:rgbArray[2] / 255];
NSNumber *alpha = [NSNumber numberWithFloat:rgbArray[3]];
return [NSArray arrayWithObjects:red, green, blue, alpha, nil];
}
`NSColor` way:
- (NSColor *) percentagesRGBArray:(float[]) rgbArray
{
CGFloat red = rgbArray[0] / 255;
CGFloat green = rgbArray[1] / 255;
CGFloat blue = rgbArray[2] / 255;
CGFloat alpha = rgbArray[3];
return [NSColor colorWithDeviceRed:red
green:green
blue:blue
alpha:alpha];
}
Problem
I'm attempting to define an extremely simple utility method that will save me from having to use a calculator to define RGB values as percentages. When I look into Apple's sample code called "QuartzCache", in the DrawView.m file, line 96, I see this: ``` float whiteColor[4] = {1, 1, 1, 1}; ``` However, when I attempt to created a method like the following, the compiler hates me. A half-hour of intensive Googling has not produced any help. ``` +(float[])percentagesRGBArray:(float[])rgbArray{ float red = rgbArray[0]; float green = rgbArray[1]; float blue = rgbArray[2]; float alpha = rgbArray[3]; red = red/255; green = green/255; blue = blue/255; alpha = alpha; float percentagesRGBArray[4] = {red, green, blue, alpha}; return percentagesRGBArray; } ``` What is the proper way to define such a method? What am I doing wrong here?