ios - 在上传到 Parse as PFFile 之前如何压缩或减小图像的大小？ ( swift )

Question

我试图在直接在手机上拍照后将图像文件上传到 Parse。但它抛出一个异常:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'PFFile cannot be larger than 10485760 bytes'

这是我的代码:

在第一个 View Controller 中:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if (segue.identifier == "getImage")
    {
        var svc = segue.destinationViewController as! ClothesDetail
        svc.imagePassed = imageView.image
    }
}

在上传图片的 View Controller 中:

let imageData = UIImagePNGRepresentation(imagePassed)
let imageFile = PFFile(name: "\(picName).png", data: imageData)

var userpic = PFObject(className:"UserPic")
userpic["picImage"] = imageFile`

但我仍然需要将那张照片上传到 Parse。有什么办法可以减小图像的大小或分辨率吗？

Answer 1

是的，您可以使用 UIImageJPEGRepresentation 而不是 UIImagePNGRepresentation 来减小图像文件的大小。您可以创建一个扩展 UIImage，如下所示:

Xcode 8.2 • Swift 3.0.2

extension UIImage {
    enum JPEGQuality: CGFloat {
        case lowest  = 0
        case low     = 0.25
        case medium  = 0.5
        case high    = 0.75
        case highest = 1
    }

    /// Returns the data for the specified image in JPEG format.
    /// If the image object’s underlying image data has been purged, calling this function forces that data to be reloaded into memory.
    /// - returns: A data object containing the JPEG data, or nil if there was a problem generating the data. This function may return nil if the image has no data or if the underlying CGImageRef contains data in an unsupported bitmap format.
    func jpeg(_ quality: JPEGQuality) -> Data? {
        return UIImageJPEGRepresentation(self, quality.rawValue)
    }
}

---

编辑/更新:

Xcode 10 swift 4.2

extension UIImage {
    enum JPEGQuality: CGFloat {
        case lowest  = 0
        case low     = 0.25
        case medium  = 0.5
        case high    = 0.75
        case highest = 1
    }

    /// Returns the data for the specified image in JPEG format.
    /// If the image object’s underlying image data has been purged, calling this function forces that data to be reloaded into memory.
    /// - returns: A data object containing the JPEG data, or nil if there was a problem generating the data. This function may return nil if the image has no data or if the underlying CGImageRef contains data in an unsupported bitmap format.
    func jpeg(_ jpegQuality: JPEGQuality) -> Data? {
        return jpegData(compressionQuality: jpegQuality.rawValue)
    }
}

---

用法:

if let imageData = image.jpeg(.lowest) {
    print(imageData.count)
}