CODEWITHSUNDEEP
iosuiimageinitializationoverridingsubclassing
potato
potato

Reputation: 4589

overriding UIImage(named: )

I was on my way to override UIImage class method init(named:). My goal is to be able to retrieve the file name of an image.

The code would look like this:

class UIImageWithFileName: UIImage {

    let fileName: String

    override init(named:String){
        super.init(named)
    fileName = named
    }
}

This code seems to be impossible for following reasons.

I created a subclass of UIImage, started typing init... and to my surprise there was no init(named:) method to override. Here is a complete list of init methods:

enter image description here

enter image description here

How does one override UIImage init(named:)

Upvotes: 6

Views: 2378

Answers (3)

MightyKip
MightyKip

Reputation: 9

I've found this to work nicely.

class MyImage: UIImage {

    convenience init?(named name: String) {
        guard let image = UIImage(named: name),
            let cgImage = image.cgImage else {
                return nil
        }
        self.init(cgImage: cgImage)
    }

}

Upvotes: 0

potato
potato

Reputation: 4589

This is a way around:

class UIImageWithName: UIImage {

var fileName: String!

func ofFile(named:String) -> UIImageWithName?{
    let cgImage = UIImage(named: named)?.CGImage
    if let validName = cgImage{
        let image = UIImageWithName(CGImage: validName)
        image.fileName = named
        return image
    }
    return nil
}

}

Not sure if it is efficient or in any way disputable. Feedback please

Upvotes: 1

Michael Dautermann
Michael Dautermann

Reputation: 89509

Turns out that "init(named:" is explicitly not inheritable.

If you look at the UIImage definition, you'll see this:

public class UIImage : NSObject, NSSecureCoding, NSCoding {

    public /*not inherited*/ init?(named name: String) // load from main bundle

    @available(iOS 8.0, *)
    public /*not inherited*/ init?(named name: String, inBundle bundle: NSBundle?, compatibleWithTraitCollection traitCollection: UITraitCollection?)

Which means you need to resolve or open the file yourself and pass in the raw data into the super class.

Upvotes: 3

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