UIImageExtension.swift

import UIKit

extension UIImage {
  func resizeImage(size: CGSize) -> UIImage? {
    UIGraphicsBeginImageContextWithOptions(size, true, 1)
    self.draw(in: CGRect(origin: CGPoint.zero, size: size))
    
    let resizedImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return resizedImage
  }
  
  func cropImage(rect: CGRect) -> UIImage? {
    guard let cutImageRef: CGImage = self.cgImage?.cropping(to: rect) else {
      return nil
    }
    let croppedImage: UIImage = UIImage(cgImage: cutImageRef, scale: self.scale, orientation: self.imageOrientation)
    return croppedImage
  }
  
  func rotateImage(orientation: UIImage.Orientation) -> UIImage? {
    let newSize: CGSize = {
      switch orientation {
      case .left, .leftMirrored, .right, .rightMirrored:
        return CGSize(width: self.size.height, height: self.size.width)
      default:
        return self.size
      }
    }()
    UIGraphicsBeginImageContextWithOptions(newSize, true, 1)
    guard let context = UIGraphicsGetCurrentContext() else {
      return nil
    }
    switch orientation {
    case .left:
      context.rotate(by: -CGFloat.pi / 2)
      self.draw(at: CGPoint(x: -self.size.width, y: 0))
    case .leftMirrored:
      context.scaleBy(x: -1, y: 1)
      context.rotate(by: CGFloat.pi / 2)
      self.draw(at: CGPoint(x: 0, y: 0))
    case .right:
      context.rotate(by: CGFloat.pi / 2)
      self.draw(at: CGPoint(x: 0, y: -self.size.height))
    case .rightMirrored:
      context.scaleBy(x: -1, y: 1)
      context.rotate(by: -CGFloat.pi / 2)
      self.draw(at: CGPoint(x: -self.size.width, y: -self.size.height))
    case .upMirrored:
      context.scaleBy(x: -1, y: 1)
      self.draw(at: CGPoint(x: -self.size.width, y: 0))
    case .down:
      context.rotate(by: CGFloat.pi)
      self.draw(at: CGPoint(x: -self.size.width, y: -self.size.height))
    case .downMirrored:
      context.scaleBy(x: 1, y: -1)
      self.draw(at: CGPoint(x: 0, y: -self.size.height))
    default:
      break
    }
    let result = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return result
  }
}