Semaphore wrapper for swift2

Semaphore.swift

import Foundation


struct Semaphore {
    typealias Signal = () -> Int

    private let semaphore: dispatch_semaphore_t

    init(count: Int = 0) {
        self.semaphore = dispatch_semaphore_create(count)
    }

    func signal() -> Int {
        return dispatch_semaphore_signal(self.semaphore)
    }

    func wait(until timeout: UInt64) -> Int {
        return dispatch_semaphore_wait(self.semaphore, timeout: timeout)
    }

    func waitForever() -> Int {
        return self.wait(until: DISPATCH_TIME_FOREVER)
    }

    func wait(until timeout: UInt64, forBlock block: (Signal) -> Void) {
        let done: Signal = {
            return self.signal()
        }

        block(done)
        return self.wait(until: timeout)
    }

    func waitForever(forBlock block: (Signal) -> Void) {
        return self.wait(until: DISPATCH_TIME_FOREVER, forBlock: block)
    }
}