HMAccessoryBrowser promises

Author: ChrisChares

Sources/HMAcessoryBrowser+Promise.swift

@@ -0,0 +1,79 @@
+//
+//  HMAcessoryBrowser+Promise.swift
+//  Onboarding
+//
+//  Created by Chris Chares on 6/29/18.
+//  Copyright © 2018 Hunter Douglas. All rights reserved.
+//
+
+import Foundation
+import HomeKit
+import PromiseKit
+
+public enum HMPromiseAccessoryBrowserError: Error {
+    case noAccessoryFound
+}
+
+public class HMPromiseAccessoryBrowser {
+    private var proxy: BrowserProxy?
+
+    public func start(scanInterval: ScanInterval) -> Promise<[HMAccessory]> {
+        return BrowserProxy(scanInterval: scanInterval).promise
+    }
+    
+    public func stop() {
+        proxy?.cancel()
+    }
+}
+
+private class BrowserProxy: PromiseProxy<[HMAccessory]>, HMAccessoryBrowserDelegate {
+    let browser = HMAccessoryBrowser()
+    let scanInterval: ScanInterval
+    
+    init(scanInterval: ScanInterval) {
+        self.scanInterval = scanInterval
+        super.init()
+        
+        browser.delegate = self;
+        browser.startSearchingForNewAccessories()
+        
+        //if we have a timeout, set it up
+        var timeout: TimeInterval? = nil
+        switch scanInterval {
+        case .returnAll(let interval): timeout = interval
+        case .returnFirst(let interval): timeout = interval
+        }
+        
+        if let timeout = timeout {
+            after(seconds: timeout)
+            .done { [weak self] () -> Void in
+                guard let _self = self else { return }
+                _self.reject(HMPromiseAccessoryBrowserError.noAccessoryFound)
+            }
+        }
+    }
+    
+    override func fulfill(_ value: [HMAccessory]) {
+        browser.stopSearchingForNewAccessories()
+        super.fulfill(value)
+    }
+    
+    override func reject(_ error: Error ) {
+        browser.stopSearchingForNewAccessories()
+        super.reject(error)
+    }
+    
+    override func cancel() {
+        browser.stopSearchingForNewAccessories()
+        super.cancel()
+    }
+    
+    /**
+        HMAccessoryBrowser delegate
+    */
+    func accessoryBrowser(_ browser: HMAccessoryBrowser, didFindNewAccessory accessory: HMAccessory) {
+        if case .returnFirst = scanInterval {
+            fulfill(browser.discoveredAccessories)
+        }
+    }
+}

Sources/PromiseProxy.swift

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+//
+//  PromiseProxy.swift
+//  HDSDK
+//
+//  Created by Chris Chares on 7/16/18.
+//  Copyright © 2018 Hunter Douglas. All rights reserved.
+//
+
+import PromiseKit
+
+/**
+    Commonly used functionality when promisifying a delegate pattern
+*/
+internal class PromiseProxy<T>: NSObject {
+    internal let (promise, seal) = Promise<T>.pending();
+    
+    private var retainCycle: PromiseProxy?
+
+    override init() {
+        super.init()
+        // Create the retain cycle
+        self.retainCycle = self
+        // And ensure we break it
+        _ = promise.ensure { self.retainCycle = nil }
+    }
+    
+    /// These functions ensure we only resolve the promise once
+    func fulfill(_ value: T) {
+        guard self.promise.isResolved == false else { return }
+        seal.fulfill(value)
+    }
+    func reject(_ error: Error) {
+        guard self.promise.isResolved == false else { return }
+        seal.reject(error)
+    }
+    
+    func cancel() {
+        self.reject(PMKError.cancelled)
+    }
+}
+
+/*
+    Commonly used intervals for scanning
+*/
+public enum ScanInterval {
+    // Return after our first item with an optional time limit
+    case returnFirst(timeout: TimeInterval?)
+    // Scan for this duration before returning all
+    case returnAll(interval: TimeInterval)
+}