Add PromiseKit dependency

- Added PromiseKit dependency

Carthage/Checkouts/PromiseKit/Extensions/AssetsLibrary/Sources/ALAssetsLibrary+Promise.swift

@@ -0,0 +1,100 @@
+import UIKit.UIViewController
+import Foundation.NSData
+import AssetsLibrary
+#if !PMKCocoaPods
+import PromiseKit
+#endif
+
+/**
+ To import this `UIViewController` extension:
+
+    use_frameworks!
+    pod "PromiseKit/AssetsLibrary"
+
+ And then in your sources:
+
+    import PromiseKit
+*/
+extension UIViewController {
+    /**
+      - Returns: A promise that presents the provided UIImagePickerController and fulfills with the user selected media’s `NSData`.
+     */
+    public func promise(_ vc: UIImagePickerController, animated: Bool = false, completion: (() -> Void)? = nil) -> Promise<NSData> {
+        let proxy = UIImagePickerControllerProxy()
+        vc.delegate = proxy
+
+        present(vc, animated: animated, completion: completion)
+
+        return proxy.promise.then(on: nil) { info -> Promise<NSData> in
+        #if swift(>=4.2)
+            let url = info[.referenceURL] as! URL
+        #else
+            let url = info[UIImagePickerControllerReferenceURL] as! URL
+        #endif
+            
+            return Promise { seal in
+                ALAssetsLibrary().asset(for: url, resultBlock: { asset in
+                    let N = Int(asset!.defaultRepresentation().size())
+                    let bytes = UnsafeMutablePointer<UInt8>.allocate(capacity: N)
+                    var error: NSError?
+                    asset!.defaultRepresentation().getBytes(bytes, fromOffset: 0, length: N, error: &error)
+
+                    if let error = error {
+                        seal.reject(error)
+                    } else {
+                        seal.fulfill(NSData(bytesNoCopy: bytes, length: N))
+                    }
+                }, failureBlock: { seal.reject($0!) } )
+            }
+        }.ensure {
+            self.dismiss(animated: animated, completion: nil)
+        }
+    }
+}
+
+@objc private class UIImagePickerControllerProxy: NSObject, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
+#if swift(>=4.2)
+    let (promise, seal) = Promise<[UIImagePickerController.InfoKey: Any]>.pending()
+#else
+    let (promise, seal) = Promise<[String: Any]>.pending()
+#endif
+    var retainCycle: AnyObject?
+
+    required override init() {
+        super.init()
+        retainCycle = self
+    }
+
+#if swift(>=4.2)
+    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey: Any]) {
+        seal.fulfill(info)
+        retainCycle = nil
+    }
+#else
+    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
+        seal.fulfill(info)
+        retainCycle = nil
+    }
+#endif
+
+    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
+        seal.reject(UIImagePickerController.PMKError.cancelled)
+        retainCycle = nil
+    }
+}
+
+
+extension UIImagePickerController {
+    /// Errors representing PromiseKit UIImagePickerController failures
+    public enum PMKError: CancellableError {
+        /// The user cancelled the UIImagePickerController.
+        case cancelled
+        /// - Returns: true
+        public var isCancelled: Bool {
+            switch self {
+            case .cancelled:
+                return true
+            }
+        }
+    }
+}