I am using core image and I am applying a CIFilter sepia tone to my image. I run a filter once in viewDidLoad and then immediately call another function that adds the filter again. For some reason, when I try to access the output image, the app crashes and says the output image is nil. Anyone know why this is happening?
Thanks
import UIKit
class ViewController: UIViewController {
@IBOutlet weak var myimage: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let image = CIImage(image: myimage.image)
let filter = CIFilter(name: "CISepiaTone")
filter.setDefaults()
filter.setValue(image, forKey: kCIInputImageKey)
myimage.image = UIImage(CIImage: filter.outputImage)
self.reapplyFilter()
}
func reapplyFilter(){
let image = CIImage(image: myimage.image)
let filter = CIFilter(name: "CISepiaTone")
filter.setDefaults()
filter.setVa lue(image, forKey: kCIInputImageKey)
//ERROR HERE: fatal error: unexpectedly found nil while unwrapping an Optional value
myimage.image = UIImage(CIImage: filter.outputImage)
//ERROR
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
You cannot call UIImage(CIImage:)
and use that UIImage as the image of a UIImageView. UIImageView requires a UIImage backed by a bitmap (CGImage). A UIImage instantiated with CIImage has no bitmap; it has no actual image, it's just a set of instructions for applying a filter. That is why your UIImageView's image is nil.
A couple of things here:
1) Using the CIImage constructor to create a CIImage based on a non CIImage backed UIImage is dangerous and will return nil or an empty CIImage.
2) When creating the image back I'd suggest you to use CIContext instead of UIImage(CIImage:).
Example:
class ViewController: UIViewController {
@IBOutlet weak var myimage: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
myimage.backgroundColor = UIColor.redColor()
self.applyFilter()
self.applyFilter()
}
func applyFilter(){
let image = CIImage(CGImage: myimage.image?.CGImage)
let filter = CIFilter(name: "CISepiaTone")
filter.setDefaults()
filter.setValue(image, forKey: kCIInputImageKey)
let context = CIContext(options: nil)
let imageRef = context.createCGImage(filter.outputImage, fromRect: image.extent())
myimage.image = UIImage(CGImage: imageRef)
}
}
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