I'm new to swift coding, so most of my code is "this is how I found it on the internet" status.
I'm trying to send a HTTP GET request and then work with it. I'm using NSURLConnection for this. I have 2 swift files in my Xcode project (it is a swift console project, not playground), one is main one and 2nd contains my class I would like to use for delegation:
import Foundation
class Remote: NSObject, NSURLConnectionDelegate {
var data = NSMutableData()
func connect() {
var url = NSURL(string: "https://www.google.com")
var request = NSURLRequest(URL: url!)
NSLog("Is%# main thread", NSThread.isMainThread() ? "" : " NOT");
var conn = NSURLConnection(request: request, delegate: self, startImmediately: false)
conn?.scheduleInRunLoop(NSRunLoop.mainRunLoop(), forMode: NSDefaultRunLoopMode)
conn?.start()
sleep(2)
}
func connection(didReceiveResponse: NSURLConnection!, didReceiveResponse response: NSURLResponse!) {
println("didReceiveResponse")
}
func connection(connection: NSURLConnection!, didReceiveData conData: NSData!) {
println("didReceiveData")
}
func connectionDidFinishLoading(connection: NSURLConnection!) {
println("DidFinishLoading")
}
deinit {
println("deiniting")
}
}
Here is my main swift code:
import Foundation
var xxx = Remote()
xxx.connect()
sleep(10)
sleep(2)
When I set breakpoints on each println in delegate functions, they are never hit. Execution is done from main thread according to NSLog output.
In debugger I can see that data are sent and received over the network, but I never get any output. I've seen many similar questions here but nothing helped me.
What am I doing wrong?
As Martin R suggested I added correct NSRunLoop into my code right after starting NSURLConnection:
self.shouldKeepRunning = true
let theRL = NSRunLoop.currentRunLoop()
while self.shouldKeepRunning && theRL.runMode(NSDefaultRunLoopMode, beforeDate: NSDate(timeInterval: 1.0, sinceDate: NSDate())) { }
shouldKeepRunning is bool variable defined in my class and it set to false in delegate function connectionDidFinishLoading, so
Related
So i have a FirstViewController where i download a video with the progress view and progress is working fine using this code
func startDownloading() {
let download = Downloads(url: videoUrl!.absoluteString!)
download.downloadTask = self.downloadsSession.downloadTaskWithURL(videoUrl!)
download.downloadTask!.resume()
download.isDownloading = true
}
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) {
// 1
print("URLSession Completed for url \(downloadTask.originalRequest?.URL?.absoluteString)")
if let originalURL = downloadTask.originalRequest?.URL?.absoluteString,
destinationURL = localFilePathForUrl(originalURL) {
let fileManager = NSFileManager.defaultManager()
do {
try fileManager.removeItemAtURL(destinationURL)
} catch {
// Non-fatal: file probably doesn't exist
}
do {
try! fileManager.copyItemAtURL(location, toURL: destinationURL)
} catch let error as NSError {
print("Could not copy file to disk: \(error.localizedDescription)")
}
}
}
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
print("URLSession inProgress \(Float(totalBytesWritten)/Float(totalBytesExpectedToWrite))")
if let downloadUrl = downloadTask.originalRequest?.URL?.absoluteString,
let download = activeDownloads[downloadUrl] {
//THIS SETS THE PROGRESS
download.progress = Float(totalBytesWritten)/Float(totalBytesExpectedToWrite)
self.downloadView.state = .Downloading
self.downloadView.setProgress(Double(totalSize)!, animated: true)
}
}
now this code updates FirstViewControllers downloadView.progress correctly but what i want is when i go to SecondViewController i should get the progress of this ongoing download in SecondVC too without starting the download progress again (i know downloading again would be very dumb).
The best way is to separate your network request manager code from the view controller:
Create a separate class to manage the requests, and move your delegate code there.
In the didWriteData method, use NSNotificationCenter to broadcast the notification to any interested view class or make your first view controller notify the second one if it exists.
In each of your view controller classes, register for the notification and when you receive it, update the status accordingly.
This is my very first program in Swift. I'm writing a basic command line (UDP) server/listener in swift using Xcode. I'm able to send data i.e. a string with characters 'testing' via the "sendData" call (verified through wireshark). However I can't seem to invoke any of the delegate callbacks. For "sendData", I've checked the implementation within #GCDAsyncUdpSocket's main file and I see that none of the delegates are called unless send we see a particular error (resolve error) in which case the "didNOTSendDataWithTag" is called.
But if "beginReceiving" is called, it does NOT invoke "didReceiveData" callback. I cant seem to find figure out why. Also "beginReceiving is suppose to be recursive (Calls itself forever I assume) according to its implementation. But my program exits quickly without any errors. Any help will be really appreciated.
import Cocoa
import CocoaAsyncSocket
class udpListener : GCDAsyncUdpSocketDelegate {
var udpSock : GCDAsyncUdpSocket?
let listenPort : UInt16 = 14000
let data = "testing".dataUsingEncoding(NSUTF8StringEncoding)
let toAddress = "127.0.0.1"
let connectPort : UInt16 = 14001
init () {
udpSock = GCDAsyncUdpSocket(delegate: self, delegateQueue: dispatch_get_main_queue())
do {
try udpSock!.bindToPort(listenPort, interface: "lo0") // Swift automatically translates Objective-C methods that produce
// errors into methods that throw an error according to Swift’s native error handling functionality.
}
catch _ as NSError {
print("Issue with binding to Port")
return }
do {
try udpSock!.beginReceiving()
}
catch _ as NSError {
print("Issue with receciving data")
return }
}
func sendData() {
udpSock!.sendData(data, toHost: toAddress, port: connectPort, withTimeout: -1, tag: 0)
}
}
// Delegate CallBacks
#objc func udpSocket(sock: GCDAsyncUdpSocket!, didReceiveData data: NSData!, fromAddress address: NSData!, withFilterContext filterContext: AnyObject!) {
let str = NSString(data: data!, encoding: NSUTF8StringEncoding)
print(str)
}
#objc func udpSocket(sock: GCDAsyncUdpSocket!, didSendDataWithTag tag: Int) {
print("didSendDataWithTag")
}
#objc func udpSocket(sock: GCDAsyncUdpSocket!, didNotSendDataWithTag tag: Int, dueToError error: NSError!) {
print("didNOTSendDataWithTag")
}
}
I'm instantiating an instance of the class from the main swift file and calling its methods in this order. Is this correct or am I missing something here
import Foundation
var dnsListener = udpListener()
dnsListener.sendData()
Here's the screenshot of the wireshark results
The main thread does not have any loop to keep it from exiting, so the execution is finished before the message is sent. If a loop or delay is added to main(), the message will be sent.
The other problem with this code is that the delegates are set to run on the main queue. The main queue is busy running the loop or delay, and can not execute the delegate code. By creating a new delegate queue, the code in the delegate functions will run.
The following code works in Swift 3.
Main code:
import Foundation
var dnsListener = UdpListener()
for i in 1...3 {
print("Sending data \(i)")
dnsListener.sendData()
sleep(3)
}
print("Execution finished")
UdpListener code:
import Foundation
import CocoaAsyncSocket
class UdpListener : NSObject, GCDAsyncUdpSocketDelegate {
var udpSock: GCDAsyncUdpSocket?
let listenPort: UInt16 = 14000
let data = "testing".data(using: String.Encoding.utf8)
let toAddress = "127.0.0.1"
let connectPort: UInt16 = 14001
override init() {
super.init()
let utilityQueue = DispatchQueue(label: "com.stackoverflow.UdpListener.utilityQueue", qos: .utility)
udpSock = GCDAsyncUdpSocket(delegate: self, delegateQueue: utilityQueue)
do {
try udpSock!.bind(toPort: listenPort, interface: "lo0")
} catch {
print("Issue with binding to Port")
return
}
do {
try udpSock!.beginReceiving()
} catch {
print("Issue with receciving data")
return
}
}
func sendData() {
udpSock!.send(data!, toHost: toAddress, port: connectPort, withTimeout: -1, tag: 0)
}
// Delegate CallBacks
func udpSocket(_ sock: GCDAsyncUdpSocket, didReceive data: Data, fromAddress address: Data, withFilterContext filterContext: Any?) {
let str = String(data: data, encoding: String.Encoding.utf8)
if let str = str {
print(str)
} else {
print("Could not decode received data")
}
}
func udpSocket(_ sock: GCDAsyncUdpSocket, didSendDataWithTag tag: Int) {
print("didSendDataWithTag")
}
func udpSocket(_ sock: GCDAsyncUdpSocket, didNotSendDataWithTag tag: Int, dueToError error: Error?) {
print("didNOTSendDataWithTag")
}
}
I am getting this error This application is modifying the autolayout engine from a background thread, which can lead to engine corruption and weird crashes.This will cause an exception in a future release. I don't know what is causing this error. Can anybody help me.
func getUserDataFromTwitterWithUser(user : PFUser)
{
//NRLoader.showLoader()
let strTwURL = "https://api.twitter.com/1.1/users/show.json? screen_name="+PFTwitterUtils.twitter()!.screenName! + "&access_token="+PFTwitterUtils.twitter()!.authToken!
let twURL = NSURL (string: strTwURL)
let request = NSMutableURLRequest(URL: twURL!, cachePolicy: NSURLRequestCachePolicy.UseProtocolCachePolicy, timeoutInterval: 2.0) as NSMutableURLRequest
PFTwitterUtils.twitter()?.signRequest(request)
let session = NSURLSession.sharedSession()
session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
if error == nil {
var jsonOptional = Dictionary<String, AnyObject>()
do {
jsonOptional = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers ) as! Dictionary<String, AnyObject>
// use jsonData
} catch {
// report error
}
var userName = ""
if let screenName = jsonOptional["screen_name"] as? String{
userName = screenName
}
else if let name = jsonOptional["name"] as? String{
userName = name
}
var profilePicUrl = ""
if let picUrl = jsonOptional["profile_image_url"] as? String{
profilePicUrl = picUrl
}
AppUser.currentUser()?.username = userName
AppUser.currentUser()?.profileAwsURL = profilePicUrl
//NRLoader.hideLoader()
//if ParseUtils.isLoggedInUserIsAnonymous() {
let signUpVC:SignMeUpViewController = self.storyboard!.instantiateViewControllerWithIdentifier("SignMeUpViewController") as! SignMeUpViewController
signUpVC.isFromLogin = true
self.navigationController!.pushViewController(signUpVC, animated: true)
//} else {
// self.pushToSubmitDreamViewController()
//}
}
else {
//NRLoader.hideLoader()
NRToast.showToastWithMessage(error!.description)
}
}).resume()
}
The dataTaskWithRequest call runs in the background and then calls your completion handler from the same thread. Anything that updates the UI should run on the main thread, so all of your current handler code should be within a dispatch_async back onto the main queue:
dispatch_async(dispatch_get_main_queue()) {
// Do stuff to UI
}
Swift 3:
DispatchQueue.main.async() {
// Do stuff to UI
}
Therefore, ideally all the code you currently have within if error == nil should be off in another function, say called handleRequest, so your current code becomes:
session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
if error == nil {
dispatch_async(dispatch_get_main_queue(), {
self.handleRequest(...)I
})
}
Swift 3
session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
if error == nil {
DispatchQueue.main.async {
self.handleRequest(...)I
}
}
Should try Symbolic Breakpoint to detect the issue:-
Then put your UI Update code in main thread
DispatchQueue.main.async {}
You'd better change UI only in the main thread
swift3,
let liveInfoUrl = URL(string: "http://192.168.1.66/api/cloud/app/liveInfo/7777")
let task = URLSession.shared.dataTask(with: liveInfoUrl! as URL) {data, response, error in
guard let data = data, error == nil else { return }
DispatchQueue.main.async {
print(String(data: data, encoding: String.Encoding(rawValue: String.Encoding.utf8.rawValue)) ?? "aaaa")
//do some ui work
}
}
if the above suggestions still give you no joy then the sure-est way is to redesign your functions so that getting what you need with
URLSession.shared.dataTask
then hands over so a variable declared outside that function, then a separate UIControl ( button, swipe etc ) displays it to a label or textview or whatever.
After all that is what the error message is telling you. they're separate concerns
I have a function, shown below, that I would like to continuously update. It is taking data from a webpage, and every so often that webpage is updated to reflect current information. Is there a way that I can catch this update and reflect that in my application? I'm pretty new to Swift and iOS programming. Some of the code made seem very bizarre, but it currently works for whatever song is playing when you first open the app (that is, it updates the text to show that song playing but doesn't update later).
let url = NSURL(string: "http://api.vicradio.org/songs/current")!
let request = NSMutableURLRequest(URL: url)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request) { (data: NSData?, response: NSURLResponse?, error: NSError?) in
if error != nil {
return
}
let name = NSString(data: data!, encoding: NSUTF8StringEncoding) as! String
var songName = ""
var artistName = "by "
var quoteNumber = 0
for character in name.characters {
if character == "\"" {
quoteNumber++
}
if quoteNumber == 3 && character != "\"" {
songName += String(character)
} else if quoteNumber == 7 && character != "\"" {
artistName += String(character)
}
}
if (songName != "no song metadata provided") {
self.SongNowText.text = songName
self.ArtistNowText.text = artistName
self.SongNowText.setNeedsDisplay()
self.ArtistNowText.setNeedsDisplay()
} else if (songName == "no song metadata provided") {
self.SongNowText.text = "The Best of What's Next!"
self.ArtistNowText.text = "only on VIC Radio"
}
}
task!.resume()
It looks like the URL you're accessing there is an API endpoint putting out JSON. I highly recommend using NSJSONSerialization.JSONObjectWithData to parse the response body into a dictionary and use that instead of rolling your own solution by counting quote marks.
The callback to dataTaskWithURL is executed on a background thread. Avoid updating the UI on anything besides the main thread because it can cause problems. Use dispatch_async to execute your UI update function on the main thread as in the example.
All you can do with this API is send it requests and read the responses. You can poll the endpoint at a regular interval while the app is open and get decent results from that. NSTimer is one way to do that, and it requires you put the method you want to execute repeatedly in a class inheriting from NSObject because it depends on Objective-C style message sending.
Throw this in a playground and try it:
import Cocoa
import XCPlayground
XCPSetExecutionShouldContinueIndefinitely()
class RadioDataAccessor : NSObject {
private let callback: [String : AnyObject] -> Void
init(callback: [String : AnyObject] -> Void) {
self.callback = callback
super.init()
NSTimer.scheduledTimerWithTimeInterval(5.0, target: self,
selector: "updateData", userInfo: nil, repeats: true)
// just so it happens quickly the first time
updateData()
}
func updateData() {
let session = NSURLSession.sharedSession()
let url = NSURL(string: "http://api.vicradio.org/songs/current")!
session.dataTaskWithURL(url) { data, response, error in
if error != nil {
return
}
var jsonError = NSErrorPointer()
let json = NSJSONSerialization.JSONObjectWithData(data,
options: NSJSONReadingOptions.allZeros,
error: jsonError) as? [String : AnyObject]
if jsonError != nil {
return
}
dispatch_async(dispatch_get_main_queue()) { self.callback(json!) }
}.resume()
}
}
RadioDataAccessor() { data in
println(data)
}
You may want to save the timer to a variable and expose a function that lets you invalidate it.
I'm trying to update a progress bar with the progress of loading a load of values into CoreData. However, whenever I try to call an update on my progressView component, I get a fatal error stating that "unexpectedly found nil while unwrapping an Optional value".
The interesting thing is that this happens even if I put 'self.progressView.progress = 0.5' in the delegate method of my program - indicating that it's the progressView component it can't find rather than an issue with the value. A quick check with println also confirms the value does exist and so isn't nil. Note that if I put the 'self.progressView.progress = 0.5' statement under a function connected directly to a button, it works fine so it must be some sort of issue with the command being called from the delegate.
Can anyone work out what I'm doing wrong here? Thanks for your help.
Delegate method:
class ViewControllerUpdate: UIViewController, NSURLSessionDelegate, NSURLSessionDownloadDelegate, saveUpdate {
[....]
func updateStatus(status: String, progress: Float?) {
if let percentProgress = progress? {
self.progressView.progress = 0.5
}
//println(progress) - NOTE THIS IS CORRECTLY POPULATED WITH THE APPROPRIATE VALUE
}
Calling class:
protocol saveUpdate {
func updateStatus(status:String, progress:Float?)
}
class sqlPullSave {
let classtoUpdate: saveUpdate = ViewControllerUpdate()
func saveTSVtoSQL(fromFile: NSURL) -> Int {
//Load up the information into a Dictionary (tsv)
//let tsvURL = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource(fromFileName, ofType: fromFileExtension)!)
let tsvURL: NSURL = fromFile
let tab = NSCharacterSet(charactersInString: "\t")
let tsv = CSV(contentsOfURL: tsvURL, separator: tab)
//let defResult: AnyObject = tsv.rows[0]["Name"]!
//let tryagain:String = AnyObjecttoString(tsv.rows[1]["Name"]!)
//load the data into the SQLite database...
dispatch_async(dispatch_get_main_queue()) {
for a in 0..<tsv.rows.count {
self.SQLsaveLine(self.AnyObjecttoString(tsv.rows[a]["Name"]!),
name_l: "",
desc: self.AnyObjecttoString(tsv.rows[a]["1"]!),
jobTitle: self.AnyObjecttoString(tsv.rows[a]["2"]!),
extn: self.AnyObjecttoString(tsv.rows[a]["3"]!)
// update status
var percentComplete: Float = (Float(a) / Float(tsv.rows.count))
self.classtoUpdate.self.updateStatus("SQLload", progress: percentComplete)
}
}
return 0
}