Zoom out to smaller in swift3

Question

I am trying to scale an image that is graphically programmed in a photo gallery. I am trying to scale the image to reduce it. How to use the code below to reduce image size

image1.scale 

Answer 1

Use this extension to resize the image:

 extension UIImage{ func resizeImageWith(newSize: CGSize) -> UIImage { let horizontalRatio = newSize.width / size.width let verticalRatio = newSize.height / size.height let ratio = max(horizontalRatio, verticalRatio) let newSize = CGSize(width: size.width * ratio, height: size.height * ratio) UIGraphicsBeginImageContextWithOptions(newSize, true, 0) draw(in: CGRect(origin: CGPoint(x: 0, y: 0), size: newSize)) let newImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return newImage! } } 

Basically you calculate the aspect ratio to keep the image the same when resized. Then you get the current context of the image and draw it in the specified rectangle and finally return it as a new image.

Answer 2

Try the following:

First method:

 func resizeImage(image: UIImage, newWidth: CGFloat) -> UIImage { let scale = newWidth / image.size.width let newHeight = image.size.height * scale UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight)) image.drawInRect(CGRectMake(0, 0, newWidth, newHeight)) let newImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return newImage } 

Second method:

 import UIKit func RBSquareImageTo(image: UIImage, size: CGSize) -> UIImage { return RBResizeImage(RBSquareImage(image), size) } func RBSquareImage(image: UIImage) -> UIImage { var originalWidth = image.size.width var originalHeight = image.size.height var edge: CGFloat if originalWidth > originalHeight { edge = originalHeight } else { edge = originalWidth } var posX = (originalWidth - edge) / 2.0 var posY = (originalHeight - edge) / 2.0 var cropSquare = CGRectMake(posX, posY, edge, edge) var imageRef = CGImageCreateWithImageInRect(image.CGImage, cropSquare); return UIImage(CGImage: imageRef, scale: UIScreen.mainScreen().scale, orientation: image.imageOrientation) } func RBResizeImage(image: UIImage, targetSize: CGSize) -> UIImage { let size = image.size let widthRatio = targetSize.width / image.size.width let heightRatio = targetSize.height / image.size.height // Figure out what our orientation is, and use that to form the rectangle var newSize: CGSize if(widthRatio > heightRatio) { newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio) } else { newSize = CGSizeMake(size.width * widthRatio, size.height * widthRatio) } // This is the rect that we've calculated out and this is what is actually used below let rect = CGRectMake(0, 0, newSize.width, newSize.height) // Actually do the resizing to the rect using the ImageContext stuff UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0) image.drawInRect(rect) let newImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return newImage } 

Link:

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Answer 3

It may be useful, this method will do proportional image resizing with good quality.

 func resizeImage(image: UIImage, withSize: CGSize) -> UIImage { var actualHeight: CGFloat = image.size.height var actualWidth: CGFloat = image.size.width let maxHeight: CGFloat = withSize.width let maxWidth: CGFloat = withSize.height var imgRatio: CGFloat = actualWidth/actualHeight let maxRatio: CGFloat = maxWidth/maxHeight let compressionQuality = 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: CGRect = CGRect(x: 0.0, y: 0.0, width: actualWidth, height: actualHeight) UIGraphicsBeginImageContext(rect.size) image.draw(in: rect) let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()! let imageData = UIImageJPEGRepresentation(image, CGFloat(compressionQuality)) UIGraphicsEndImageContext() let resizedImage = UIImage(data: imageData!) return resizedImage! } 

Call these methods as follows:

 resizeImage(image: UIImage(named: "ImageName"), withSize: CGSize(width: 300, height: 300)) 

Thanks:)

Answer 4

  func resizeImage(image: UIImage, newWidth: CGFloat) -> UIImage { let scale = newWidth / image.size.width let newHeight = image.size.height * scale UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight)) image.drawInRect(CGRectMake(0, 0, newWidth, newHeight)) let newImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return newImage } @IBAction func chooseImage(sender: AnyObject) { var myPickerController = UIImagePickerController() myPickerController.sourceType = UIImagePickerControllerSourceType.PhotoLibrary myPickerController.delegate = self; self.presentViewController(myPickerController, animated: true, completion: nil) } func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) { var image = info[UIImagePickerControllerOriginalImage] as? UIImage let scaledImage:UIImage = resizeImage(image!, newWidth: 200) self.dismissViewControllerAnimated(true, completion: nil) } 

version of Swift 4

 extension UIImage { func resize(withWidth newWidth: CGFloat) -> UIImage? { let scale = newWidth / self.size.width let newHeight = self.size.height * scale UIGraphicsBeginImageContext(CGSize(width: newWidth, height: newHeight)) self.draw(in: CGRect(x: 0, y: 0, width: newWidth, height: newHeight)) let newImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return newImage } }