在应用程序启动OSX上运行代码

Question

I am looking for a way to have a certain bit of code run constantly as soon as the application starts up. I am trying to make a simple peer to peer chat application using swiftSockets .

import Cocoa
import CryptoSwift

class MasterViewController: NSViewController {

    @IBOutlet var msgField: NSTextField!
    @IBOutlet var msgWindow: NSTextView!

    let server:UDPServer = UDPServer(addr: "127.0.0.1", port: 5000)

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    func receive() {
        let data = server.recv(1024)
        let string = NSData.withBytes(data.0!)
        let str = NSString(data: string, encoding: NSUTF8StringEncoding) as String?
        msgWindow.string! += server.addr + " says: " + str! + "\n"
    }

    @IBAction func send(sender: NSButton) {
        msgWindow.string! += "I said: " + msgField.stringValue + "\n"
        msgField.stringValue = ""
        server.send(str: msgField.stringValue)
        let data = server.recv(1024)
        let string = NSData.withBytes(data.0!)
        let str = NSString(data: string, encoding: NSUTF8StringEncoding) as String?
        msgWindow.string! += server.addr + " says: " + str! + "\n"
    }
}

I have the code above, the send works great, however, How can i get the receive function to run in the background as soon as the application is run?

Answer 1

Simply call your receive function in the viewDidLoad() or viewDidAppear() function. To have run it in the background, consider dispatch_async() or dispatch_sync()

let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
    // do some tasks, in this case call receive()
    dispatch_async(dispatch_get_main_queue()) {
        // update some UI
    }
}

If you just want to run it periodically without the necessity of transferring it to the background, consider using an NSTimer, and call its scheduledTimerWithTimeInterval function similar to this:

let timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: "receive", userInfo: nil, repeats: true)

with the first parameter being the interval in seconds, selector the function you want to periodically call (in this case receive).