如何在Swift中调整CGImage大小

Question

我想调整CGImage的大小并使其变小。似乎有为UIImage开发的工具/算法，但不适用于swift/objective-c中的CGImage。

Answer 1

extension CGImage { 
    func resize(scale:CGFloat)-> CGImage { 
     let image = UIImage(CGImage: self)! 
     let imageView = UIImageView(frame: CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: image.size.width*scale, height: image.size.height*scale))) 
     imageView.contentMode = UIViewContentMode.ScaleAspectFit 
     imageView.image = image 
     UIGraphicsBeginImageContext(imageView.bounds.size) 
     imageView.layer.renderInContext(UIGraphicsGetCurrentContext()) 
     let result = UIGraphicsGetImageFromCurrentImageContext() 
     UIGraphicsEndImageContext() 
     return result.CGImage 
    } 
} 

let myPic = UIImage(data: NSData(contentsOfURL: NSURL(string:"http://i.stack.imgur.com/Xs4RX.jpg")!)!)!.CGImage 

let thumb = UIImage(CGImage: myPic.resize(0.1))