Decrease text alpha effect swift [duplicate] - ios

Question

I'm trying to draw a gradient to UILabel, but it draws only the colors I can't see the text.
I saw the code from here StackOverflow
my modification:
extension String{
func gradient(x:CGFloat,y:CGFloat, fontSize:CGFloat)->UIImage{
let font:UIFont = UIFont.systemFontOfSize(fontSize)
let name:String = NSFontAttributeName
let textSize: CGSize = self.sizeWithAttributes([name:font])
let width:CGFloat = textSize.width // max 1024 due to Core Graphics limitations
let height:CGFloat = textSize.height // max 1024 due to Core Graphics limitations
UIGraphicsBeginImageContext(CGSizeMake(width, height))
let context = UIGraphicsGetCurrentContext()
UIGraphicsPushContext(context!)
//draw gradient
let glossGradient:CGGradientRef?
let rgbColorspace:CGColorSpaceRef?
let num_locations:size_t = 2
let locations:[CGFloat] = [ 0.0, 1.0 ]
let components:[CGFloat] = [(202 / 255.0), (197 / 255.0), (52 / 255.0), 1.0, // Start color
(253 / 255.0), (248 / 255.0), (101 / 255.0), 1.0] // End color
rgbColorspace = CGColorSpaceCreateDeviceRGB()
glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations)
let topCenter = CGPointMake(0, 0);
let bottomCenter = CGPointMake(0, textSize.height);
CGContextDrawLinearGradient(context, glossGradient, topCenter, bottomCenter, CGGradientDrawingOptions.DrawsBeforeStartLocation)
UIGraphicsPopContext()
let gradientImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return gradientImage
}
}
and the setup of the imageView
self.timeLeftIV = UIImageView(frame: CGRectMake(self.pyramidFakeView.frame.origin.x/2-25,0, 100,20))
self.timeLeftIV.image = "59:48".gradient(timeLeftIV.frame.origin.x, y: timeLeftIV.frame.origin.y, fontSize: 6.0)
the result of the code:

Answer 1

There is an easier way of getting a gradient as a UIImage. You can use a CAGradientLayer. For example:
func yellowGradientImage(bounds:CGRect) -> UIImage
{
let gradientLayer = CAGradientLayer()
gradientLayer.colors = [UIColor(red: (202 / 255.0), green: (197 / 255.0), blue: (52 / 255.0), alpha: 1.0).CGColor, UIColor(red: (253 / 255.0), green: (248 / 255.0), blue: (101 / 255.0), alpha: 1.0).CGColor]
gradientLayer.bounds = bounds
UIGraphicsBeginImageContextWithOptions(gradientLayer.bounds.size, true, 0.0)
let context = UIGraphicsGetCurrentContext()
gradientLayer.renderInContext(context!)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
To apply the gradient to text you next need to use the image returned as the textColor using UIColor(patternImage: ...). For example:
let label = UILabel()
label.font = UIFont.systemFontOfSize(150.0)
label.text = "HELLO WORLD"
label.sizeToFit()
let image = yellowGradientImage(label.bounds)
label.textColor = UIColor(patternImage: image)
Which results in:
swift 3.0:
func yellowGradientImage(bounds:CGRect) -> UIImage
{
let gradientLayer = CAGradientLayer()
gradientLayer.colors = [UIColor(red: (202 / 255.0), green: (197 / 255.0), blue: (52 / 255.0), alpha: 1.0).cgColor, UIColor(red: (253 / 255.0), green: (248 / 255.0), blue: (101 / 255.0), alpha: 1.0).cgColor]
gradientLayer.bounds = bounds
UIGraphicsBeginImageContextWithOptions(gradientLayer.bounds.size, true, 0.0)
let context = UIGraphicsGetCurrentContext()
gradientLayer.render(in: context!)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image!
}
let label = UILabel()
label.font = UIFont.systemFont(ofSize: 150.0)
label.text = "HELLO WORLD"
label.sizeToFit()
let image = yellowGradientImage(bounds: label.bounds)
label.textColor = UIColor(patternImage: image)

Answer 2

add a view, modify draw rect with below code.
override func drawRect(rect: CGRect) {
// Drawing code
let currentContext = UIGraphicsGetCurrentContext()
CGContextSaveGState(currentContext);
let colorSpace = CGColorSpaceCreateDeviceRGB()
let startColor = UIColor(red: 0.1, green: 0.0, blue: 0.0, alpha: 0.0)
let startColorComponents = CGColorGetComponents(startColor.CGColor)
let middleColor = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.2)
let middleColorComponents = CGColorGetComponents(middleColor.CGColor)
let lowerMiddleColor = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.3)
let lowerMiddleColorComponents = CGColorGetComponents(lowerMiddleColor.CGColor)
let endColor = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.5)
let endColorComponents = CGColorGetComponents(endColor.CGColor)
var colorComponents = [startColorComponents[0], startColorComponents[1], startColorComponents[2], startColorComponents[3], middleColorComponents[0], middleColorComponents[1], middleColorComponents[2], middleColorComponents[3], lowerMiddleColorComponents[0], lowerMiddleColorComponents[1], lowerMiddleColorComponents[2], lowerMiddleColorComponents[3], endColorComponents[0], endColorComponents[1], endColorComponents[2], endColorComponents[3]]
var locations:[CGFloat] = [0.0, 0.6, 0.8, 1.0]
let gradient = CGGradientCreateWithColorComponents(colorSpace,&colorComponents,&locations,4)
let startPoint = CGPointMake(0, 0)
let endPoint = CGPointMake(0, self.bounds.height)
CGContextAddRect(currentContext, CGRect(x: 0, y: 0, width: self.bounds.width, height: self.bounds.height));
CGContextClip(currentContext);
CGContextDrawLinearGradient(currentContext,gradient,startPoint,endPoint, CGGradientDrawingOptions.DrawsBeforeStartLocation)
CGContextRestoreGState(currentContext)
}
Now in storyboard add a view change class to your gradient class and add a label to this view.
See if it works for you.