如何在上传到Parse之前将图片的大小缩小为PFFile？ （迅速）

我试图直接在手机上拍照后上传图片文件到Parse。 但它引发了一个例外：

终止应用程序由于未捕获的exception“NSInvalidArgumentException”，原因：“PFFile不能大于10485760字节”

这是我的代码：

在第一视图控制器中：

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

在视图控制器上传图像：

 let imageData = UIImagePNGRepresentation(imagePassed) let imageFile = PFFile(name: "\(picName).png", data: imageData) var userpic = PFObject(className:"UserPic") userpic["picImage"] = imageFile` 

但是我仍然需要把这张照片上传到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less您的图像文件大小。 你可以创build一个扩展UIImage如下：

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) } } 

用法：

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

---

Answer 2

如果你想限制图像的大小，以一些具体的价值，你可以做如下：

 import UIKit extension UIImage { // MARK: - UIImage+Resize func compressTo(_ expectedSizeInMb:Int) -> UIImage? { let sizeInBytes = expectedSizeInMb * 1024 * 1024 var needCompress:Bool = true var imgData:Data? var compressingValue:CGFloat = 1.0 while (needCompress && compressingValue > 0.0) { if let data:Data = UIImageJPEGRepresentation(self, compressingValue) { if data.count < sizeInBytes { needCompress = false imgData = data } else { compressingValue -= 0.1 } } } if let data = imgData { if (data.count < sizeInBytes) { return UIImage(data: data) } } return nil } } 

Answer 3

Jus Fixing for Xcode 7，在2015年9月21日testing，工作正常：

只需创build一个扩展UIImage如下：

 extension UIImage { var highestQualityJPEGNSData: NSData { return UIImageJPEGRepresentation(self, 1.0)! } var highQualityJPEGNSData: NSData { return UIImageJPEGRepresentation(self, 0.75)!} var mediumQualityJPEGNSData: NSData { return UIImageJPEGRepresentation(self, 0.5)! } var lowQualityJPEGNSData: NSData { return UIImageJPEGRepresentation(self, 0.25)!} var lowestQualityJPEGNSData: NSData { return UIImageJPEGRepresentation(self, 0.0)! } } 

那么你可以像这样使用它：

 let imageData = imagePassed.lowestQualityJPEGNSData 

Answer 4

  //image compression func resizeImage(image: UIImage) -> UIImage { var actualHeight: Float = Float(image.size.height) var actualWidth: Float = Float(image.size.width) let maxHeight: Float = 300.0 let maxWidth: Float = 400.0 var imgRatio: Float = actualWidth / actualHeight let maxRatio: Float = maxWidth / maxHeight let compressionQuality: Float = 0.5 //50 percent compression if actualHeight > maxHeight || actualWidth > maxWidth { if imgRatio < maxRatio { //adjust width according to maxHeight imgRatio = maxHeight / actualHeight actualWidth = imgRatio * actualWidth actualHeight = maxHeight } else if imgRatio > maxRatio { //adjust height according to maxWidth imgRatio = maxWidth / actualWidth actualHeight = imgRatio * actualHeight actualWidth = maxWidth } else { actualHeight = maxHeight actualWidth = maxWidth } } let rect = CGRectMake(0.0, 0.0, CGFloat(actualWidth), CGFloat(actualHeight)) UIGraphicsBeginImageContext(rect.size) image.drawInRect(rect) let img = UIGraphicsGetImageFromCurrentImageContext() let imageData = UIImageJPEGRepresentation(img!,CGFloat(compressionQuality)) UIGraphicsEndImageContext() return UIImage(data: imageData!)! } 

Answer 5

Swift 3

// @ leo-dabus回答修改为3

  extension UIImage { var uncompressedPNGData: Data? { return UIImagePNGRepresentation(self) } var highestQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 1.0) } var highQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 0.75) } var mediumQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 0.5) } var lowQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 0.25) } var lowestQualityJPEGNSData:Data? { return UIImageJPEGRepresentation(self, 0.0) } }