NSRecursiveLock.swift

import Foundation

// NSRecursiveLock - It is used to write thread safe code
// Locks needs to be balanced.

class Logger {
    let recursiveLock = NSRecursiveLock()
    
    func doSomething() {
        recursiveLock.lock()
        
        createSomething()
        
        recursiveLock.unlock()
    }
    
    func createSomething() {
        recursiveLock.lock()
        
        print("thread safe code!!!")
        
        recursiveLock.unlock()
    }
}


let logger = Logger()
logger.doSomething()
logger.createSomething()