title: Issue when I'm trying to draw gradient in swift
body: <p>I got an error when I was trying to draw gradient in Swift code:</p>
  
  <blockquote>
    <p>GradientView.swift:31:40: Could not find an overload for '__conversion' that accepts the supplied arguments</p>
  </blockquote>
  
  <p>Here is my code:</p>
  
  <pre><code>let context: CGContextRef = UIGraphicsGetCurrentContext()
  let locations: CGFloat[] = [ 0.0, 0.25, 0.5, 0.75 ]
  let colors = [UIColor.redColor().CGColor, UIColor.greenColor().CGColor,UIColor.blueColor().CGColor, UIColor.yellowColor().CGColor]
  let colorspace: CGColorSpaceRef = CGColorSpaceCreateDeviceRGB()
  let gradient: CGGradientRef = CGGradientCreateWithColors(colorspace, colors, locations)
  //CGGradientCreateWithColors(colorspace,colors,locations)
  let startPoint: CGPoint = CGPointMake(0, 0)
  let endPoint: CGPoint = CGPointMake(500,500)
  CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
  </code></pre>
  
  <p>The problem is the CGGradientCreateWithColors takes CFArray not a normal Swift Array. I have no idea how to convert CFArray to Array and can't find anything in Apple's document. Any idea? Thanks</p>