关于渐变色设置 Gradient

今天项目有个progressView 设置渐变色的需求，发现可以设置progressImage来实现，前提是生成渐变色的图片
Progress原文链接

以下是生成渐变色图片代码

public enum GradientOrientation {
    case vertical
    case horizontal
}

convenience init?(bounds: CGRect, colors: [UIColor], orientation: GradientOrientation = .horizontal) {
        let gradientLayer = CAGradientLayer()
        gradientLayer.frame = bounds
        gradientLayer.colors = colors.map({ $0.cgColor })
        
        if orientation == .horizontal {
            gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5);
            gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5);
        }
        
        UIGraphicsBeginImageContextWithOptions(gradientLayer.bounds.size, false, UIScreen.main.scale)
        gradientLayer.render(in: UIGraphicsGetCurrentContext()!)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        guard let cgImage = image?.cgImage else { return nil }
        self.init(cgImage: cgImage)
    }

UILabel渐变色，也可以通过生成图片来实现

Swift
label.textColor = UIColor(patternImage: progressImage!)

OC
[UIColor colorWithPatternImage:[UIImage imageNamed:@"backImage.png"]];