An example of composition.

ChainedCompositionExample.swift

import Foundation

protocol VideoFilter {
    func addFilter(completion: @escaping (Bool) -> Void)
}

struct ChainedFilter: VideoFilter {
    let primary: VideoFilter
    let next: VideoFilter
    
    func addFilter(completion: @escaping (Bool) -> Void) {
        primary.addFilter { (success) in
            if success {
                next.addFilter(completion: completion)
            } else {
                // depend on how to handle failure
                completion(false)
            }
        }
    }
}

extension VideoFilter {
    func chain(_ filter: VideoFilter) -> VideoFilter {
        ChainedFilter(primary: self, next: filter)
    }
}


struct TrimmerFilter: VideoFilter {
    func addFilter(completion: @escaping (Bool) -> Void) {
        // implement logic
        print("Trimmed!")
        completion(true)
    }
}

struct SubtileFilter: VideoFilter {
    func addFilter(completion: @escaping (Bool) -> Void) {
        // implement logic
        print("Added Subtitle!")
        completion(true)
    }
}

struct SpeedChangerFilter: VideoFilter {
    func addFilter(completion: @escaping (Bool) -> Void) {
        // implement logic
        print("Changed Speed!")
        completion(true)
    }
}

let filter = TrimmerFilter()
    .chain(SubtileFilter())
    .chain(SpeedChangerFilter())

filter.addFilter { (success) in
    if success {
        print("All Process Succeeded!")
    } else {
        print("Process Failed!")
    }
}