UIImage is equal to

Question

I need to check if a file loaded into an UIImage object file is equal to another image and execute some actions if so. Unfortunately, it\'s not working.

Answer 1

You can go even further an implement the equality operator on UIImage, which will ease your logic when it comes to comparing images:

func ==(lhs: UIImage, rhs: UIImage) -> Bool {
    lhs.pngData() == rhs.pngData()
}

This also enables the != operator on UIImage.

Answer 2

You cannot compare two UIImage objects using the != or == operators, one option is comparing as NSData using the UIImagePNGRepresentation to convert it to NSData objects, like in the following code:

func areEqualImages(img1: UIImage, img2: UIImage) -> Bool {

   guard let data1 = UIImagePNGRepresentation(img1) else { return false }
   guard let data2 = UIImagePNGRepresentation(img2) else { return false }

   return data1.isEqualToData(data2)
}

I hope this help you.

Answer 3

You can convert your UIImage instances to NSData instances and compare them.

if let emptyImage = UIImage(named: "empty") {
    let emptyData = UIImagePNGRepresentation(emptyImage)
    let compareImageData = UIImagePNGRepresentation(image1.image)

    if let empty = emptyData, compareTo = compareImageData {
        if empty.isEqualToData(compareTo) {
            // Empty image is the same as image1.image
        } else {
            // Empty image is not equal to image1.image
        }
    } else {
        // Creating NSData from Images failed
    }
}