how to make a gradient border of UIView?

Question

I want to make a gradient border of view like the following picture:

but I don't know how do it exactly , i.e. what the gradient color I should use to do it? how to set my view to show a border like the image?

I'm using the following code to get a border:

 self.view.layer.borderColor = [UIColor orangeColor].CGColor;  self.view.layer.borderWidth = 2.0f; 

Answer 1

This what i did and it worked perfectly

   extension CALayer {     func addGradienBorder(colors:[UIColor],width:CGFloat = 1) {         let gradientLayer = CAGradientLayer()         gradientLayer.frame =  CGRect(origin: CGPointZero, size: self.bounds.size)         gradientLayer.startPoint = CGPointMake(0.0, 0.5)         gradientLayer.endPoint = CGPointMake(1.0, 0.5)         gradientLayer.colors = colors.map({$0.CGColor})          let shapeLayer = CAShapeLayer()         shapeLayer.lineWidth = width         shapeLayer.path = UIBezierPath(rect: self.bounds).CGPath         shapeLayer.fillColor = nil         shapeLayer.strokeColor = UIColor.blackColor().CGColor         gradientLayer.mask = shapeLayer          self.addSublayer(gradientLayer)     }  }