Add objective-c interoperability (#19)

* Add objective-c interoperability

* Add parameter to delegates method.

* Fix comment

KZFileWatchers.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'KZFileWatchers'
-  s.version          = '1.0.5'
+  s.version          = '1.0.6'
   s.summary          = 'A micro-framework for observing file changes, both local and remote. Helpful in building developer tools.'
 
   s.description      = <<-DESC

ObjcWrappers/FileWatcherProtocols.swift

@@ -0,0 +1,45 @@
+//
+//  FileWatcherProtocols.swift
+//  KZFileWatchers
+//
+//  Created by Andrey Morozov on 18/12/2018.
+//
+
+import Foundation
+
+/**
+Protocol for essence, that responsible for file refresh processing.
+*/
+@objc(FileWatcherDelegate)
+public protocol FileWatcherOutput: NSObjectProtocol {
+
+	/// Fires, when monitoring file is updated.
+	///
+	/// - Parameters:
+	///	  - fileWatcher: The file watcher, which handles file refreshing.
+	///   - type: Status of refresh result.
+	///   - data: Content from file.
+	func refreshDidOccur(from fileWatcher: FileWatcherInput, type: RefreshResultType, data: Data?)
+}
+
+/**
+Protocol for File Watchers.
+*/
+@objc(FileWatcherProtocol)
+public protocol FileWatcherInput: NSObjectProtocol {
+
+	/// Responsible for file refresh processing.
+	var delegate: FileWatcherOutput? { get set }
+
+	/**
+	Starts observing file changes, a file watcher can only have one callback.
+	*/
+	@objc(startWithError:)
+	func start() throws
+
+	/**
+	Stops observing file changes.
+	*/
+	@objc(stopWithError:)
+	func stop() throws
+}

ObjcWrappers/LocalFileWatcher.swift

@@ -0,0 +1,67 @@
+//
+//  LocalFileWatcher.swift
+//  KZFileWatchers
+//
+//  Created by Andrey Morozov on 18/12/2018.
+//
+
+import Foundation
+
+/**
+Watcher for local files, it uses content diffing.
+*/
+@objc
+public final class LocalFileWatcher: NSObject {
+
+	/// Original local FileWatcher, that does all work.
+	private let localWatcher: FileWatcher.Local
+
+	public weak var delegate: FileWatcherOutput?
+
+	/**
+	Initializes watcher to specified path.
+	
+	- parameter path:     Path of file to observe.
+	
+	- note: By default it throttles to 60 FPS, some editors can generate stupid multiple saves that mess with file system e.g. Sublime with AutoSave plugin is a mess and generates different file sizes, this will limit wasted time trying to load faster than 60 FPS, and no one should even notice it's throttled.
+	*/
+	@objc
+	public convenience init(path: String) {
+		self.init(path: path, refreshInterval: 1/60, queue: DispatchQueue.main)
+	}
+
+	/**
+	Initializes watcher to specified path.
+	
+	- parameter path:     Path of file to observe.
+	- parameter refreshInterval: Refresh interval to use for updates.
+	- parameter queue:    Queue to use for firing `onChange` callback.
+	*/
+	@objc
+	public init(path: String, refreshInterval: TimeInterval, queue: DispatchQueue) {
+		localWatcher = FileWatcher.Local(path: path, refreshInterval: refreshInterval, queue: queue)
+	}
+
+	@objc
+	public func refresh() {
+		localWatcher.refresh()
+	}
+}
+
+extension LocalFileWatcher: FileWatcherInput {
+
+	public func start() throws {
+		try localWatcher.start { (result) in
+			switch result {
+			case .noChanges:
+				self.delegate?.refreshDidOccur(from: self, type: .noChanges, data: nil)
+			case .updated(let data):
+				self.delegate?.refreshDidOccur(from: self, type: .updated, data: data)
+			}
+		}
+	}
+
+	public func stop() throws {
+		try localWatcher.stop()
+	}
+}

ObjcWrappers/RefreshResultType.swift

@@ -0,0 +1,24 @@
+//
+//  RefreshResultType.swift
+//  KZFileWatchers
+//
+//  Created by Andrey Morozov on 18/12/2018.
+//
+
+import Foundation
+
+/**
+Enum that contains status of refresh result.
+*/
+@objc(RefreshResult)
+public enum RefreshResultType: Int {
+	/**
+	Watched file didn't change since last update.
+	*/
+	case noChanges
+
+	/**
+	Watched file did change.
+	*/
+	case updated
+}

ObjcWrappers/RemoteFileWatcher.swift

@@ -0,0 +1,66 @@
+//
+//  RemoteFileWatcher.swift
+//  KZFileWatchers
+//
+//  Created by Andrey Morozov on 18/12/2018.
+//
+
+import Foundation
+
+/**
+Watcher for remote files, it supports both ETag and Last-Modified HTTP header tags.
+*/
+@objc
+public final class RemoteFileWatcher: NSObject {
+
+	/// Original remote FileWatcher, that does all work.
+	private let remoteWatcher: FileWatcher.Remote
+
+	public weak var delegate: FileWatcherOutput?
+
+	/**
+	Creates a new watcher using given URL and refreshInterval.
+	
+	- parameter url:             URL to observe.
+	
+	- note: By default, it uses refreshInterval equal to 1.
+	*/
+	@objc
+	public convenience init(url: URL) {
+		self.init(url: url, refreshInterval: 1)
+	}
+
+	/**
+	Creates a new watcher using given URL and refreshInterval.
+	
+	- parameter url:             URL to observe.
+	- parameter refreshInterval: Minimal refresh interval between queries.
+	*/
+	@objc
+	public init(url: URL, refreshInterval: TimeInterval) {
+		remoteWatcher = FileWatcher.Remote(url: url, refreshInterval: refreshInterval)
+	}
+
+	@objc
+	public func refresh() throws {
+		try remoteWatcher.refresh()
+	}
+}
+
+extension RemoteFileWatcher: FileWatcherInput {
+
+	public func start() throws {
+		try remoteWatcher.start { (result) in
+			switch result {
+			case .noChanges:
+				self.delegate?.refreshDidOccur(from: self, type: .noChanges, data: nil)
+			case .updated(let data):
+				self.delegate?.refreshDidOccur(from: self, type: .updated, data: data)
+			}
+		}
+	}
+
+	public func stop() throws {
+		try remoteWatcher.stop()
+	}
+}

README.md

@@ -18,6 +18,26 @@ This framework provides:
 
 - `FileWatcher.Remote` can be used to observe files on the web, it supports both `Etag` headers and `Last-Modified-Date` so you can just put file on Dropbox or real ftp server.
 
+It also supports usage from Objective-C projects. For this, you should consider these following steps:
+
+1. Add `$(TOOLCHAIN_DIR)/usr/lib/swift/$(PLATFORM_NAME)` into your projects **Library Search Paths** in **Build Setting** section.
+
+2. Import swift-header by adding `@import KZFileWatchers;` into any `.m` file, where you want to use FileWatchers.
+
+3. Use provided classes for set up file observing like this:
+```objectivec
+self.fileWatcher = [[LocalFileWatcher alloc] initWithPath:path];
+self.fileWatcher.delegate = self;
+[self.fileWatcher startWithError:nil];
+```
+4. Implement `FileWatcherDelegate` in your class for handling file refreshing events. For example:
+```objectivec
+- (void)refreshDidOccurFrom:(id<FileWatcherProtocol>)fileWatcher type:(enum RefreshResult)type data:(NSData *)data
+{
+    self.textLabel.text = [[NSString alloc] initWithData:data encoding:kCFStringEncodingUTF8];
+}
+```
+
 ## Installation
 
 KZFileWatchers is available through [CocoaPods](http://cocoapods.org) and [Swift Package Manager](http://github.com/apple/swift-package-manager).