如何调整 UIImage 的大小以减小上传图像的大小

How do I resize the UIImage to reduce upload image size(如何调整 UIImage 的大小以减小上传图像的大小)

问题描述

我一直在搜索谷歌，并且只遇到过降低高度/宽度或通过 CoreImage 编辑 UIImage 外观的库.但是我还没有看到或找到一个库，帖子解释了如何减小图像大小，所以当它上传时，它不是完整的图像大小.

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:

so far I have this:

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

")
        body.appendData(data)
        body.appendString("
")
    }

它正在发送 12MB 的照片.我怎样才能把它减少到1mb?谢谢！

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

推荐答案

Xcode 9 • Swift 4 或更高版本

编辑/更新:对于iOS10+我们可以使用UIGraphicsImageRenderer.对于较旧的 Swift 语法检查编辑历史记录.

edit/update: For iOS10+ We can use UIGraphicsImageRenderer. For older Swift syntax check edit history.

extension UIImage {
    func resized(withPercentage percentage: CGFloat, isOpaque: Bool = true) -> UIImage? {
        let canvas = CGSize(width: size.width * percentage, height: size.height * percentage)
        let format = imageRendererFormat
        format.opaque = isOpaque
        return UIGraphicsImageRenderer(size: canvas, format: format).image {
            _ in draw(in: CGRect(origin: .zero, size: canvas))
        }
    }
    func resized(toWidth width: CGFloat, isOpaque: Bool = true) -> UIImage? {
        let canvas = CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height)))
        let format = imageRendererFormat
        format.opaque = isOpaque
        return UIGraphicsImageRenderer(size: canvas, format: format).image {
            _ in draw(in: CGRect(origin: .zero, size: canvas))
        }
    }
}

用法:

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

let thumb1 = image.resized(withPercentage: 0.1)
let thumb2 = image.resized(toWidth: 72.0)

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