typealias + Function with return value

Playground.swift

import SwiftUI

typealias Filter = (CGImage) -> CGImage

func blur(radius: Double) -> Filter {
    return { image in
        // Do  something.
        return image
    }
}

let url = Bundle.main.url(forResource: "Landscape/Landscape_0", withExtension: "jpg")!
SImage().createImage(from: url) { cgImage in
    if let image = cgImage {
        let sameImage = blur(radius: 2.0)(image) // 👈🏻
        sameImage
    }
}