压缩图片

///图片压缩方法
func resetImgSize(sourceImage:UIImage, maxImageLength:CGFloat, maxSizeKB:CGFloat) -> UIImage {
    var maxSize = maxSizeKB
    var maxImageSize = maxImageLength
    if (maxSize <= 0.0) {
        maxSize = 1024.0
    }
    if (maxImageSize <= 0.0) {
        maxImageSize = 1024.0
    }
    //先调整分辨率
    var newSize = CGSize.init(width: sourceImage.size.width, height: sourceImage.size.height)
    let tempHeight = newSize.height/maxImageSize
    let tempWidth = newSize.width/maxImageSize;
    if (tempWidth > 1.0 && tempWidth > tempHeight) {
        newSize = CGSize.init(width: sourceImage.size.width / tempWidth, height: sourceImage.size.height / tempWidth)
    } else if (tempHeight > 1.0 && tempWidth < tempHeight){
        newSize = CGSize.init(width: sourceImage.size.width / tempHeight, height: sourceImage.size.height / tempHeight)
    }
    UIGraphicsBeginImageContext(newSize)
    sourceImage.draw(in: CGRect.init(x: 0, y: 0, width: newSize.width, height: newSize.height))
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    var imageData = UIImageJPEGRepresentation(newImage!, 1.0)
    var sizeOriginKB : CGFloat = CGFloat((imageData?.count)!) / 1024.0
    //调整大小
    var resizeRate = 0.9
    while (sizeOriginKB > maxSize && resizeRate > 0.1) {
        imageData = UIImageJPEGRepresentation(newImage!,CGFloat(resizeRate))
        sizeOriginKB = CGFloat((imageData?.count)!) / 1024.0
        resizeRate -= 0.1
    }
    return UIImage.init(data: imageData!)!
}