UIImageJPEGRepresentation增加UIImage大小

Question

我有一個圖像（captureImage）這是由相機和調整大小。我使用UIImageJPEGRepresentation來壓縮圖像，壓縮後圖像的大小增加。這是正常行爲還是我以錯誤的方式進行壓縮/調整大小？

if let image = captureImage { 
    print(image.size) // (700, 700) 
    let compressedImageData = UIImageJPEGRepresentation(image, 0.3)! 
    let compressedImage = UIImage(data: compressedImageData)! 
    print(compressedImage.size) // (3024, 3024) 
} 

Answer 1

是這個代碼的圖像壓縮得到該文件的大小

let compressedImageData = UIImageJPEGRepresentation(image, 0.3)! 

一種方式是通過保存到文件目錄。 例如 -

let filePath = fileURL 
     var fileSize : UInt64 

     do { 
      //return [FileAttributeKey : Any] 
      let attr = try FileManager.default.attributesOfItem(atPath: filePath.path) 
      fileSize = attr[FileAttributeKey.size] as! UInt64 

      //if you convert to NSDictionary, you can get file size old way as well. 
      let dict = attr as NSDictionary 
      fileSize = dict.fileSize() 
      print(fileSize) 

     } catch { 
      print("Error: \(error)") 
     }