一些学习过程中的难点解决

例子

class ViewController: UIViewController {
    let lock = NSLock()
    var person = Person(name: "Leo",age: 23)
    override func viewDidLoad() {
        super.viewDidLoad()
        let queue1 = dispatch_queue_create("com.test.queue1",DISPATCH_QUEUE_SERIAL)
        let queue2 = dispatch_queue_create("com.test.queue1",DISPATCH_QUEUE_SERIAL)
        dispatch_async(queue1) { () -> Void in
            self.lock.lock()
            self.person.update("queue1",delay: 2,age: 1)
            self.lock.unlock()
        }
        dispatch_async(queue2) { () -> Void in
            self.lock.lock()
            self.person.update("queue2",delay: 1,age: 2)
            self.lock.unlock()
        }
        self.performSelector("logPerson",withObject: nil,afterDelay: 4)
        // Do any additional setup after loading the view,typically from a nib.
    }
    func logPerson(){
        NSLog("%@ %d",person.name,person.age)
    }

}

这样就会当执行 self.person.update(“queue2”,delay: 1,age: 2)时候锁定，执行完后释放锁，然后下一个线程才会重新调用update，这样数据不会错乱

case .Failure(let error):
      if response.response?.statusCode == 401{//刷新token
      dispatch_async(queue3) { () -> Void in
         lock?.lock()//这里添加互斥锁，防止一起刷新token，这样就会分开之行token方法cjq
        RefreshToken({ (AnyObject) in
            lock?.unlock()
            var hs = headers
            hs!["Authorization"] = NSUserDefaults.standardUserDefaults().stringForKey("access_token")
        }
     },logout: { (NSError) in
              logout?()
              lock?.unlock()
              })
      }
 }else{
    failure?(error)
        }
  }