DepInjection.swift

//: Playground - noun: a place where people can play

import UIKit

//Everything starts with defining a protocol
protocol Logger {
    func log(_ mex: String)
}

//This is one implementation of the protocol
class LocalLogger: Logger {
    
    func log(_ mex: String) {
        print(mex)
    }
}

//We can define one protocol that all the objects that need a logger can implement
protocol HasLogger {
    var logger: Logger { get }
}

//Who needs a logger doesn't need to do anything because the HasLogger protocol
//has one default implementation
extension HasLogger {
    var logger: Logger {
        return LocalLogger()
    }
}



//this is the class that need a logger, we just make the class implement the protocol.
class ObjectWithDependencies: HasLogger {

    func doSomething() {
        self.logger.log("Now I can use a logger")
    }
}


ObjectWithDependencies().doSomething()