Applying Gradient to UIImage Smoothly

Question

I am trying to apply gradient to UIImage using CoreGraphic; however, the result I got is not very nice. I want to create a black to transparent gradient at the bottom of the ima

Answer 1

SWIFT 3

func imageWithGradient(img:UIImage!) -> UIImage {

    UIGraphicsBeginImageContext(img.size)
    let context = UIGraphicsGetCurrentContext()

    img.draw(at: CGPoint(x: 0, y: 0))

    let colorSpace = CGColorSpaceCreateDeviceRGB()
    let locations:[CGFloat] = [0.0, 1.0]

    let bottom = UIColor(red: 0, green: 0, blue: 0, alpha: 0.5).cgColor
    let top = UIColor(red: 0, green: 0, blue: 0, alpha: 0).cgColor

    let colors = [top, bottom] as CFArray

    let gradient = CGGradient(colorsSpace: colorSpace, colors: colors, locations: locations)

    let startPoint = CGPoint(x: img.size.width/2, y: 0)
    let endPoint = CGPoint(x: img.size.width/2, y: img.size.height)

    context!.drawLinearGradient(gradient!, start: startPoint, end: endPoint, options: CGGradientDrawingOptions(rawValue: UInt32(0)))

    let image = UIGraphicsGetImageFromCurrentImageContext()

    UIGraphicsEndImageContext()

    return image!
}