照片调整大小和压缩

Question

I am resizing and compressing my photos an unusual result.

When I choose the image from photo album, the image compresses and resizes fine. However, If I do it on a image that was passed from the camera, the image becomes oddly small (And unwatchable). What I have done as a test is assign some compression and resizing function in my button that takes an image either from a camera source or photo album. Below are my code and console output

@IBAction func testBtnPressed(sender: AnyObject) {
    let img = selectedImageView.image!
    print("before resize image \(img.dataLengh_kb)kb size \(img.size)")

    let resizedImg = img.resizeWithWidth(1080)
    print("1080 After resize image \(resizedImg!.dataLengh_kb)kb size \(resizedImg!.size)")

    let compressedImageData = resizedImg!.mediumQualityJPEGNSData
    print("Compress to medium quality = \(compressedImageData.length / 1024)kb")
}

extension UIImage {
    var mediumQualityJPEGNSData: NSData  { return UIImageJPEGRepresentation(self, 0.5)!  }

    func resizeWithWidth(width: CGFloat) -> UIImage? {
        let imageView = UIImageView(frame: CGRect(origin: .zero, size: CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height)))))
        imageView.contentMode = .ScaleAspectFit
        imageView.image = self
        UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, false, scale)
        guard let context = UIGraphicsGetCurrentContext() else { return nil }
        imageView.layer.renderInContext(context)
        guard let result = UIGraphicsGetImageFromCurrentImageContext() else { return nil }
        UIGraphicsEndImageContext()
        return result
    }
}

When photo was selected from photo album

before resize image 5004kb size (3024.0, 3024.0)

1080 After resize image 1023kb size (1080.0, 1080.0)

Compress to medium quality = 119kb

When photo was passed by camera

before resize image 4653kb size (24385.536, 24385.536)

1080 After resize image 25kb size (1080.576, 1080.576)

Compress to medium quality = 4kb

Answer 1

I have replaced the image resizing function with the following one and it worked a lot better

func resizeImage(newHeight: CGFloat) -> UIImage {

    let scale = newHeight / self.size.height
    let newWidth = self.size.width * scale
    UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight))
    self.drawInRect(CGRectMake(0, 0, newWidth, newHeight))
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage
}