Swift - Cropping images *outside* of allowsEditing - swift

Question

I have a very very simple project set up that allows you to click a "browse photo" button. The user then selects a photo from their photo gallery, and it's displayed on a programmatically created UIImageView.
Works like a charm. However - I am missing key functionality that is required.
I need the user to be able to scale the image (via pinching and dragging) after it is displayed within the UIImageView. allowsEditing = true, lets the user crop before. I need similar functionality, however, allowing them to edit once it's on the main UI.
Help is appreciated. Please and thank you!!
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var imageView: UIImageView!
var imageViewLayer: CALayer{
return imageView.layer
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
imageViewLayer.contents = UIImage(named: "ss3.jpg")?.CGImage
imageViewLayer.contentsGravity = kCAGravityResizeAspect
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func newGesture(sender: AnyObject) {
imageViewLayer.transform = CATransform3DMakeScale(sender.scale, sender.scale, 1)
}
}

Answer 1

I did something similar a while back. I added the image to UIImageView's layer property, added gesture recognizer to the view and implemented the gesture call backs modifying the layer property and not the view. Adding the image to the UIImageView's layer did the trick. As a side note, I would like to add that every UIView is supported by CALayer class. It has a lot of methods and properties which help to dynamically change the view, which in your case will be done by gestures.
As an alternative, you can also use CALayer's hitTest method instead of implementing the call backs for gesture recognizers.
EDIT- Sample Code
You could do some thing like this:
#IBOutlet weak var imageView: UIImageView!
var imageViewLayer: CALayer{
return imageView.layer
}
In the viewDidLoad, set up the image
imageViewLayer.contents = UIImage(named: "CoreDataDemoApp")?.CGImage
imageViewLayer.contentsGravity = kCAGravityResizeAspect
Add pinch gesture to the imageview in storyboard (or programmatically) and in it's call back you could do something like this:
#IBAction func pinchGestureRecognized(sender: AnyObject) {
imageViewLayer.transform = CATransform3DMakeScale(sender.scale, sender.scale, 1)
}
Again this is just to give you an idea of how it could work and it is not the complete code. Hope this helps!
This is another way of doing it:
Stackoverflow link to related question