How to set color of templated image in NSTextAttachment

Question

How can I set the color of a templated image that is an attachment on an attributed string?

Background:

I\'ve got a UILabel and I\'m setting its attributedTe

Answer 1

I have good experience with using the library UIImage+Additions when tinting UIImage instances. Specially check section IV.

If adding a third-party library is not an option, here is something to get you started:

- (UIImage *)colorImage:(UIImage *)image color:(UIColor *)color
{
    UIGraphicsBeginImageContextWithOptions(image.size, NO, [UIScreen mainScreen].scale);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextTranslateCTM(context, 0, image.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    CGRect rect = CGRectMake(0, 0, image.size.width, image.size.height);

    CGContextSetBlendMode(context, kCGBlendModeNormal);
    CGContextDrawImage(context, rect, image.CGImage);
    CGContextSetBlendMode(context, kCGBlendModeSourceIn);
    [color setFill];
    CGContextFillRect(context, rect);


    UIImage *coloredImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return coloredImage;
}

This will make a UIImage go from:

To

Update: Swift version:

extension UIImage {
    func colorImage(with color: UIColor) -> UIImage? {
        guard let cgImage = self.cgImage else { return nil }
        UIGraphicsBeginImageContext(self.size)
        let contextRef = UIGraphicsGetCurrentContext()

        contextRef?.translateBy(x: 0, y: self.size.height)
        contextRef?.scaleBy(x: 1.0, y: -1.0)
        let rect = CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height)

        contextRef?.setBlendMode(CGBlendMode.normal)
        contextRef?.draw(cgImage, in: rect)
        contextRef?.setBlendMode(CGBlendMode.sourceIn)
        color.setFill()
        contextRef?.fill(rect)

        let coloredImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return coloredImage
    }
}