图片压缩处理

import Foundation
import UIKit

extension UIImage {
    //compress image to quality(0,1)
    class func compressImageToQuality(image:UIImage, quality:CGFloat) -> UIImage {
        if quality >= 1 || quality <= 0 {
            return image
        }

        //compress image data
        let imageData = UIImageJPEGRepresentation(image, quality)

        if let data = imageData {
            return UIImage(data: data)!
        }

        return image

    }

    //compress image to scale size
    class func scaleImageToSize(image:UIImage, size:CGSize) -> UIImage {

        let width = size.width
        let height = size.height
        if width == 0 || height == 0 {
            return image
        }
        //Create a graphics image context with new size
        UIGraphicsBeginImageContext(size)
        //draw scale image in rect
        image.drawInRect(CGRect(x: 0, y: 0, width: width, height: height))
        //get the scale image from the context
        let scaleImage = UIGraphicsGetImageFromCurrentImageContext()
        //remove the current context from the top of the stack
        UIGraphicsEndImageContext()

        return scaleImage
    }
}