Simple extension on XCTestExpectation to allow to specify an expectation count. see following test for exemple

XCTestExpectationExtensions.swift

//
//  XCTestExpectationExtensions.swift
//
//  Created by Hugues Bernet-Rollande on 7/4/16.
//

import XCTest

extension XCTestExpectation {
    private class IntWrapper {
        let value :Int!
        init?(value:Int?) {
            self.value = value
            if (value == nil) {
                return nil
            }
        }
    }
    
    private struct AssociatedKey {
        static var expectationCountKey = ""
    }
    
    
    var expectationCount:Int? {
        get {
            return objc_getAssociatedObject(self, &AssociatedKey.expectationCountKey) as? Int
        }
        set {
            objc_setAssociatedObject(self, &AssociatedKey.expectationCountKey, newValue, .OBJC_ASSOCIATION_RETAIN)
        }
    }
    
    func decrementalFulfill() {
        guard let expectationCount = self.expectationCount else {
            fulfill()
            return
        }
        self.expectationCount = expectationCount - 1
        if self.expectationCount <= 0 {
            fulfill()
        }
    }
}

class XCTestExpectationExtensionsTests: XCTestCase {
    
    func testMultiple() {
        weak var e = expectationWithDescription("call twice")
        e?.expectationCount = 2
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(0.1 * Double(NSEC_PER_SEC))), dispatch_get_main_queue(), {
            e?.decrementalFulfill()
            e?.decrementalFulfill()
        })
        waitForExpectationsWithTimeout(1.0, handler: nil)
    }
    
    func testNil() {
        weak var e = expectationWithDescription("call once")
        e?.expectationCount = 2
        e?.expectationCount = nil
        XCTAssertNil(e?.expectationCount)
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(0.1 * Double(NSEC_PER_SEC))), dispatch_get_main_queue(), {
            e?.decrementalFulfill()
        })
        waitForExpectationsWithTimeout(1.0, handler: nil)
    }
    
}

Updating to use weak reference to expectation