将图像转换为数据和反之亦然 [英] Converting an Image to Data and Vice Versa

问题描述

我在Xcode中使用swift，我需要将图像转换为数据，以便将其保存在SQLite数据库中，并在从数据库中检索数据时将数据对象转换回图像。
请帮忙吗？
Simon

I am using swift in Xcode and I need to convert an image to data in order to save it in SQLite db and also to convert the data object back to an image when I retrieve it from the database. Any help please? Simon

推荐答案

Xcode 8.3.1•Swift 3.1

要从 UIImage 转换为数据，您可以使用 UIImagePNGRepresentation 或 UIImageJPEGRepresentation 如果你需要减小文件大小。

To convert from UIImage to Data you can use UIImagePNGRepresentation or UIImageJPEGRepresentation if you need to reduce the file size.

extension UIImage {
    var jpeg: Data? {
        return UIImageJPEGRepresentation(self, 1)   // QUALITY min = 0 / max = 1
    }
    var png: Data? {
        return UIImagePNGRepresentation(self)
    }
}

To从数据转换回图像你只需要使用 UIImage（数据:) 初始值设定项：

To convert back to Image from Data you just need to use UIImage(data:) initializer:

extension Data {
    var uiImage: UIImage? {
        return UIImage(data: self)
    }
}

---

游乐场

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Playground

let image = UIImage(data: try! Data(contentsOf: URL(string: "https://i.stack.imgur.com/Xs4RX.jpg")!))!
if let jpegData = image.jpeg {
    print(jpegData.count) // 416318   number of bytes contained by the data object
    if let imageFromData =  jpegData.uiImage {
        print(imageFromData.size)  // (719.0, 808.0)
    }
}
if let pngData = image.png {
    print(pngData.count)  // 1282319
    if let imageFromData =  pngData.uiImage {
        print(imageFromData.size)  // (719.0, 808.0)
    }
}

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