如何调整UIImage的大小以减少上传图像大小 [英] How do I resize the UIImage to reduce upload image size

问题描述

我一直在搜索谷歌，并且只遇到了可以降低高度/宽度的库或者通过CoreImage编辑UIImage外观的库。但我没有看到或找到一个图书馆，帖子解释了如何减少图像尺寸，所以当它上传时，它不是完整的图像尺寸。

I've been searching google, and have only come across libraries that either reduce the height/width or some how edit the UIImage appearance via CoreImage. But I have not seen or found one library, post that explains how to reduce image size so when it uploads, it's not the full image size.

到目前为止我有这个：

        if image != nil {
        //let data = NSData(data: UIImagePNGRepresentation(image))
        let data = UIImagePNGRepresentation(image)
        body.appendString("--\(boundary)\r\n")
        body.appendString("Content-Disposition: form-data; name=\"image\"; filename=\"randomName\"\r\n")
        body.appendString("Content-Type: image/png\r\n\r\n")
        body.appendData(data)
        body.appendString("\r\n")
    }

并发送12MB照片。我怎样才能减少到1mb？谢谢！

and it's sending 12MB photos. How can I reduce this to 1mb? thanks!

推荐答案

Xcode 8.2.1•Swift 3.0.2

extension UIImage {
    func resized(withPercentage percentage: CGFloat) -> UIImage? {
        let canvasSize = CGSize(width: size.width * percentage, height: size.height * percentage)
        UIGraphicsBeginImageContextWithOptions(canvasSize, false, scale)
        defer { UIGraphicsEndImageContext() }
        draw(in: CGRect(origin: .zero, size: canvasSize))
        return UIGraphicsGetImageFromCurrentImageContext()
    }
    func resized(toWidth width: CGFloat) -> UIImage? {
        let canvasSize = CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height)))
        UIGraphicsBeginImageContextWithOptions(canvasSize, false, scale)
        defer { UIGraphicsEndImageContext() }
        draw(in: CGRect(origin: .zero, size: canvasSize))
        return UIGraphicsGetImageFromCurrentImageContext()
    }
}

用法：

let myPicture = UIImage(data: try! Data(contentsOf: URL(string:"http://i.stack.imgur.com/Xs4RX.jpg")!))!

let myThumb1 = myPicture.resized(withPercentage: 0.1)
let myThumb2 = myPicture.resized(toWidth: 72.0)

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