'Cancel' for PromiseKit option 2

Cartfile

@@ -1 +1,4 @@
-github "mxcl/PromiseKit" ~> 6.0
+#github "mxcl/PromiseKit" ~> 6.0
+github "dougzilla32/PromiseKit" "PMKCancel"
+#github "PromiseKit/Cancel" ~> 1.0
+github "dougzilla32/Cancel" ~> 1.0

Cartfile.resolved

@@ -1 +1,2 @@
-github "mxcl/PromiseKit" "6.3.3"
+github "dougzilla32/Cancel" "1.0.0"
+github "dougzilla32/PromiseKit" "a0217bd7b69af68237dcdeee0197e63259b9d445"

PMKStoreKit.xcodeproj/project.pbxproj

@@ -204,6 +204,7 @@
 			);
 			inputPaths = (
 				PromiseKit,
+				PMKCancel,
 			);
 			name = "Embed Carthage Frameworks";
 			outputPaths = (

Sources/SKProductsRequest+Promise.swift

@@ -1,5 +1,6 @@
 import StoreKit
 #if !PMKCocoaPods
+import PMKCancel
 import PromiseKit
 #endif
 
@@ -50,3 +51,40 @@ fileprivate class SKDelegate: NSObject, SKProductsRequestDelegate {
 //        return true
 //    }
 //}
+
+//////////////////////////////////////////////////////////// Cancellation
+
+extension SKProductsRequest {
+    /**
+     Sends the request to the Apple App Store.
+
+     - Returns: A cancellable promise that fulfills if the request succeeds.
+     */
+    public func startCC(_: PMKNamespacer) -> CancellablePromise<SKProductsResponse> {
+        let proxy = SKDelegate()
+        delegate = proxy
+        proxy.retainCycle = proxy
+        let cp = CancellablePromise(task: SKRequestTask(self, proxy), promise: proxy.promise, resolver: proxy.seal)
+
+        start()
+        return cp
+    }
+}
+
+fileprivate class SKRequestTask: CancellableTask {
+    let request: SKRequest
+    let proxy: SKDelegate
+
+    init(_ request: SKRequest, _ proxy: SKDelegate) {
+        self.request = request
+        self.proxy = proxy
+    }
+
+    var isCancelled = false
+
+    func cancel() {
+        request.cancel()
+        proxy.retainCycle = nil
+        isCancelled = true
+    }
+}

Sources/SKReceiptRefreshRequest+Promise.swift

@@ -1,4 +1,5 @@
 #if !PMKCocoaPods
+import PMKCancel
 import PromiseKit
 #endif
 import StoreKit
@@ -9,7 +10,7 @@ extension SKReceiptRefreshRequest {
     }
 }
 
-private class ReceiptRefreshObserver: NSObject, SKRequestDelegate {
+private class ReceiptRefreshObserver: NSObject, SKRequestDelegate, CancellableTask {
     let (promise, seal) = Promise<SKReceiptRefreshRequest>.pending()
     let request: SKReceiptRefreshRequest
     var retainCycle: ReceiptRefreshObserver?
@@ -32,4 +33,21 @@ private class ReceiptRefreshObserver: NSObject, SKRequestDelegate {
         seal.reject(error)
         retainCycle = nil
     }
+
+    var isCancelled = false
+
+    func cancel() {
+        request.cancel()
+        retainCycle = nil
+        isCancelled = true
+    }
+}
+
+//////////////////////////////////////////////////////////// Cancellation
+
+extension SKReceiptRefreshRequest {
+    public func promiseCC() -> CancellablePromise<SKReceiptRefreshRequest> {
+        let rro = ReceiptRefreshObserver(request: self)
+        return CancellablePromise(task: rro, promise: rro.promise, resolver: rro.seal)
+    }
 }

Tests/TestStoreKit.swift

@@ -1,3 +1,4 @@
+import PMKCancel
 import PMKStoreKit
 import PromiseKit
 import StoreKit
@@ -20,3 +21,33 @@ class SKProductsRequestTests: XCTestCase {
         waitForExpectations(timeout: 1, handler: nil)
     }
 }
+
+//////////////////////////////////////////////////////////// Cancellation
+
+extension SKProductsRequestTests {
+    func testCancel() {
+        class MockProductsRequest: SKProductsRequest {            
+            var isCancelled = false
+
+            override func start() {
+                after(seconds: 0.1).done {
+                    if !self.isCancelled {
+                        self.delegate?.productsRequest(self, didReceive: SKProductsResponse())
+                    }
+                }
+            }
+        }
+
+        let ex = expectation(description: "")
+
+        let request = MockProductsRequest()
+        request.startCC(.promise).done { _ in
+            XCTFail()
+        }.catch(policy: .allErrors) {
+            $0.isCancelled ? ex.fulfill() : XCTFail()
+        }.cancel()
+        request.isCancelled = true
+
+        waitForExpectations(timeout: 1, handler: nil)
+    }
+}