Mutual exclusion in Swift (equivalent to @synchronized in obj-c)

SwiftSynchronized.swift

/**
Function that locks an object while it is being acted upon in the closure parameter. 
Rethrows allows the function to throw an error for throwing closures or not for non-throwing closures (do not need `try` for non-throwing closures). 
parameter lock: Object to be sync'd
parameter closure: Code of critical section
*/
public func synchronized<T>(lock: AnyObject, @noescape closure: () throws -> T) rethrows -> T {
    objc_sync_enter(lock)
    defer {
        objc_sync_exit(lock)
    }
    return try closure()
}