Creating a UIImage from a UIColor to use as a background image for UIButton

Question

I'm creating a colored image like this:

CGRect rect = CGRectMake(0, 0, 1, 1);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,
                                   [[UIColor redColor] CGColor]);
//  [[UIColor colorWithRed:222./255 green:227./255 blue: 229./255 alpha:1] CGColor]) ;
CGContextFillRect(context, rect);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

and then use it as the background image of a button:

[resultButton setBackgroundImage:img forState:UIControlStateNormal];

This works great using the redColor, however I want to use an RGB color (as shown in the commented line). When I use the RGB color, the buttons background isn't changed.

What am I missing?

Answer 1

I created a category around UIButton to be able to set the background color of the button and set the state. You might find this useful.

@implementation  UIButton (ButtonMagic)

- (void)setBackgroundColor:(UIColor *)backgroundColor forState:(UIControlState)state {
    [self setBackgroundImage:[UIButton imageFromColor:backgroundColor] forState:state];
}

+ (UIImage *)imageFromColor:(UIColor *)color {
    CGRect rect = CGRectMake(0, 0, 1, 1);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

This will be part of a set of helper categories I'm open sourcing this month.

Swift 2.2

extension UIImage {
static func fromColor(color: UIColor) -> UIImage {
    let rect = CGRect(x: 0, y: 0, width: 1, height: 1)
    UIGraphicsBeginImageContext(rect.size)
    let context = UIGraphicsGetCurrentContext()
    CGContextSetFillColorWithColor(context, color.CGColor)
    CGContextFillRect(context, rect)
    let img = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return img
  }
}

Swift 3.0

extension UIImage {
    static func from(color: UIColor) -> UIImage {
        let rect = CGRect(x: 0, y: 0, width: 1, height: 1)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()
        context!.setFillColor(color.cgColor)
        context!.fill(rect)
        let img = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return img!
    }
}

Use as

let img = UIImage.from(color: .black)