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109
Samples/Playgrounds/LastEventsConsole.playground/Contents.swift
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| import PlaygroundSupport | ||
| import UIKit | ||
| import DXFeedFramework | ||
|
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| /** | ||
| * This sample demonstrates a way to subscribe to the big world of symbols with dxFeed API, so that the events are | ||
| * updated and cached in memory of this process, and then take snapshots of those events from memory whenever | ||
| * they are needed. This example repeatedly reads symbol name from the console and prints a snapshot of its last | ||
| * quote, trade, summary, and profile events. | ||
| */ | ||
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| let records = "Quote,Trade,Summary,Profile" | ||
| let symbols = "http://dxfeed.s3.amazonaws.com/masterdata/ipf/demo/mux-demo.ipf.zip" | ||
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| let endpoint = try DXEndpoint.builder() | ||
| .withProperty("dxfeed.qd.subscribe.ticker", records + " " + symbols) | ||
| .build().connect("demo.dxfeed.com:7300") | ||
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| guard let feed = endpoint.getFeed() else { | ||
| exit(-1) | ||
| } | ||
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| func fetchData(feed: DXFeed, symbol: String) throws { | ||
| print("begin fetching for \(symbol)") | ||
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| /* | ||
| * The first step is to extract promises for all events that we are interested in. This way we | ||
| * can get an event even if we have not previously subscribed for it. | ||
| */ | ||
| let qPromise = try feed.getLastEventPromise(type: Quote.self, symbol: symbol) | ||
| let tPromise = try feed.getLastEventPromise(type: Trade.self, symbol: symbol) | ||
| let sPromise = try feed.getLastEventPromise(type: Summary.self, symbol: symbol) | ||
| /* | ||
| * All promises are put into a list for convenience. | ||
| */ | ||
| var promises = [qPromise, tPromise, sPromise] | ||
| /* | ||
| * Profile events are composite-only. They are not available for regional symbols like | ||
| * "IBM&N" and the attempt to retrieve never completes (will timeout), so we don't event try. | ||
| */ | ||
| if !MarketEventSymbols.hasExchangeCode(symbol) { | ||
| var pPromise = try feed.getLastEventPromise(type: Profile.self, symbol: symbol) | ||
| promises.append(pPromise) | ||
| } | ||
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| /* | ||
| * If the events are available in the in-memory cache, then the promises will be completed immediately. | ||
| * Otherwise, a request to the upstream data provider is sent. Below we combine promises using | ||
| * Promises utility class from DXFeed API in order to wait for at most 1 second for all of the | ||
| * promises to complete. The last event promise never completes exceptionally and we don't | ||
| * have to specially process a case of timeout, so "awaitWithoutException" is used to continue | ||
| * normal execution even on timeout. This sample prints a special message in the case of timeout. | ||
| */ | ||
| if try Promise.allOf(promises: promises)?.awaitWithoutException(millis: 1000) == false { | ||
| print("Request timed out") | ||
| } | ||
| /* | ||
| * The combination above is used only to ensure a common wait of 1 second. Promises to individual events | ||
| * are completed independently and the corresponding events can be accessed even if some events were not | ||
| * available for any reason and the wait above had timed out. This sample just prints all results. | ||
| * "null" is printed when the event is not available. | ||
| */ | ||
| try promises.forEach { pr in | ||
| print(try pr.getResult()?.toString() ?? "Null result for \(pr)") | ||
| } | ||
| print("end fetching for \(symbol)") | ||
| } | ||
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| // Just UI for symbol input | ||
| class V: UIViewController { | ||
| var textField = UITextField() | ||
| var feed: DXFeed! | ||
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| override func viewDidLoad() { | ||
| super.viewDidLoad() | ||
| view.addSubview(textField) | ||
| textField.translatesAutoresizingMaskIntoConstraints = false | ||
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| textField.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 0).isActive = true | ||
| textField.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: 0).isActive = true | ||
| textField.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: 15).isActive = true | ||
| textField.trailingAnchor.constraint(equalTo: self.view.trailingAnchor, constant: -15).isActive = true | ||
| textField.placeholder = "Type symbols to get their quote, trade, summary, and profile event snapshots" | ||
| textField.delegate = self | ||
| } | ||
| } | ||
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| extension V: UITextFieldDelegate { | ||
| func textFieldShouldReturn(_ textField: UITextField) -> Bool { | ||
| do { | ||
| try fetchData(feed: feed, symbol: textField.text ?? "") | ||
| } catch { | ||
| print("Error during fetching: \(error)") | ||
| } | ||
| textField.text = "" | ||
| return true | ||
| } | ||
| } | ||
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| let view = V() | ||
| view.feed = feed | ||
| view.view.frame = CGRect(x: 0, y: 0, width: 400, height: 150) | ||
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| PlaygroundPage.current.liveView = view.view | ||
| PlaygroundPage.current.needsIndefiniteExecution = true | ||
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Samples/Playgrounds/LastEventsConsole.playground/contents.xcplayground
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| <?xml version="1.0" encoding="UTF-8" standalone="yes"?> | ||
| <playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'> | ||
| <timeline fileName='timeline.xctimeline'/> | ||
| </playground> |