Today I'm trying to get some data from a webpage.
It keeps crashing saying "Exc Bad Access", any suggestion ?
class CodeViewController: NSObject {
#IBOutlet var output_box : NSTextField
#IBOutlet var url_textField : NSTextField
var output : NSString = "Unable to load data"
func downloadHTML (path: String) -> String {
var url = NSURL(string: "\(path)")
var request = NSURLRequest(URL: url)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {(response, data, error) in
self.output = NSString(data: data, encoding: NSUTF8StringEncoding)
//EXC_BAD_ACCESS when trying to set self.output new value
}
return output
}
#IBAction func retrive(sender: AnyObject!) {
println(downloadHTML(url_textField.stringValue))
}
}
I suspect that "url_textField.stringValue" is nil at the point that you pass it in. Trying it with a fixed string works. But note also that the function will return before the async request completes, and so your code will always print "Unable to load". If you add a line that assigns the output to your output_box in the completion handler, you will see the the text box update once the request completes...
The code I tried, which works, is...
class CodeViewController: NSObject {
var output : NSString = "Unable to load data"
func downloadHTML (path: String) -> String {
var url = NSURL(string: "\(path)")
var request = NSURLRequest(URL: url)
let completionBlock: (NSURLResponse!, NSData!, NSError!) -> Void = {response, data, error in
self.output = NSString(data: data, encoding: NSUTF8StringEncoding)
println("Asynch completed \(self.output)")
}
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue(), completionHandler: completionBlock)
return output
}
}
var c: CodeViewController? = nil
c = CodeViewController()
c!.downloadHTML("http://www.google.com")
println("Immediate \(c!.output)")
and its output is:
Immediate Unable to load data
Asynch completed <!doctype html><html ...
Related
I want to load images into connectionDidFinishLoading method and the method func connection(_connection: NSURLConnection, didReceive: Data) is not getting called
class ImageDownload: UIImageView,NSURLConnectionDelegate,NSURLConnectionDataDelegate
{
var imageSaved:UIImage!
var imageDownloaded:UIImage!
var connection2:NSURLConnection = NSURLConnection()
var data: NSMutableData = NSMutableData()
var urlstring:String = ""
var fileURL:URL!
let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true) as NSArray
var pathPlist:String!
func downloadImage()
{
let imgdownload :String = "http://image.tmdb.org/t/p/w500" + urlstring
// let urlnew: NSURL = NSURL(string: imgdownload)!
//print(urlnew,"url")
let url: NSURL = NSURL(string: imgdownload)!
let request1: NSMutableURLRequest = NSMutableURLRequest(url: url as URL)
// let request2: NSMutableURLRequest = NSMutableURLRequest(url: urlnew as URL, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 60.0)
connection2 = NSURLConnection(request: request1 as URLRequest, delegate: self, startImmediately: false)!
connection2.start()
}
func setURL(url:String) -> Void
{
print(url,"url")
urlstring = url
let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
fileURL = documentsDirectory.appendingPathComponent(url)
print(fileURL,"fileurl")
if FileManager.default.fileExists(atPath: fileURL.path)
{
let image = UIImage(contentsOfFile: fileURL.path)
print("file exists")
self.image = image
}
else
{
downloadImage()
//let imgdownload :String = "http://image.tmdb.org/t/p/w500" + url
// let request = URL(string: imgdownload)
// let myUrl = NSURL(string: imgdownload)
//print("image loaded")
// self.image = self.imageSaved
}
}
func connection(_ connection: NSURLConnection, didReceive response: URLResponse)
{
print("in didReceive response\n")
self.data = NSMutableData()
}
func connection(_connection: NSURLConnection, didReceive: Data)
{
print("in didReceive data\n")
self.data.append(data as Data)
print(data,"image data is")
}
func connection(_ connection: NSURLConnection, didFailWithError error: Error)
{
print("connection error = \(error)")
}
func connectionDidFinishLoading(_ connection: NSURLConnection)
{
}
}*
I'm not familiar with the Swift syntax for NSURLConnection, so there's a nonzero chance I'm missing something subtle with the delegate method names, but off the top of my head, I see a couple of bigger problems:
Why are you using NSURLConnection in Swift? Every version of iOS that supports Swift also has NSURLSession. Just use the shared session, and your behavior will be almost identical to NSURLConnection.
You're using HTTP URLs. In all recent versions of iOS, you have to add special bits to your Info.plist if you want your app to be able to access HTTP URLs. I do not recommend doing that. Just use HTTPS.
You can get free TLS certs for HTTPS from Let's Encrypt. My guess is that as soon as you set that up and switch to an HTTPS URL, your problems will go away even with the existing code. But you should still be using NSURLSession.
I am writing a library, So not using UIKit, Even in my iOS app same code works, but when i execute in command line in doesn't . In PlayGround also it seems working.
For some reason callback is not getting triggered, so print statements are not executing.
internal class func post(request: URLRequest, responseCallback: #escaping (Bool, AnyObject?) -> ()) {
execTask(request: request, taskCallback: { (status, resp) -> Void in
responseCallback(status, resp)
})
}
internal class func clientURLRequest(url: URL, path: String, method: RequestMethod.RawValue, params: Dictionary<String, Any>? = nil) -> URLRequest {
var request = URLRequest(url: url)
request.httpMethod = method
do {
let jsonData = try JSONSerialization.data(withJSONObject: (params! as [String : Any]), options: .prettyPrinted)
request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
request.httpBody = jsonData
} catch let error as NSError {
print(error)
}
return request
}
private class func execTask(request: URLRequest, taskCallback: #escaping (Bool,
AnyObject?) -> ()) {
let session = URLSession(configuration: URLSessionConfiguration.default)
print("THIS LINE IS PRINTED")
let task = session.dataTask(with: request, completionHandler: {(data, response, error) -> Void in
if let data = data {
print("THIS ONE IS NOT PRINTED")
let json = try? JSONSerialization.jsonObject(with: data, options: [])
if let response = response as? HTTPURLResponse , 200...299 ~= response.statusCode {
taskCallback(true, json as AnyObject?)
} else {
taskCallback(false, json as AnyObject?)
}
}
})
task.resume()
}
Edits -: I am writing a library, So not using UIKit, Even in my iOS app same code works, but when i execute in command line in doesn't . In PlayGround also it seems working.
I made a simple App from scratch. (Xcode 8 beta 6 / swift 3)
In controller I pasted Your code. (plus url creation..)
I see all in debugger:
THIS ONE IS PRINTED
THIS ONE IS PRINTED, TOO
I AM BACK
so it seems workin.
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let URLString = "https://apple.com"
let url = URL(string: URLString)
let request = URLRequest(url: url!)
ViewController.execTask(request: request) { (ok, obj) in
print("I AM BACK")
}
}
private class func execTask(request: URLRequest, taskCallback: #escaping (Bool,
AnyObject?) -> ()) {
let session = URLSession(configuration: URLSessionConfiguration.default)
print("THIS LINE IS PRINTED")
let task = session.dataTask(with: request, completionHandler: {(data, response, error) -> Void in
if let data = data {
print("THIS ONE IS PRINTED, TOO")
let json = try? JSONSerialization.jsonObject(with: data, options: [])
if let response = response as? HTTPURLResponse , 200...299 ~= response.statusCode {
taskCallback(true, json as AnyObject?)
} else {
taskCallback(false, json as AnyObject?)
}
}
})
task.resume()
}
}
I know its late for the answer but in case you have not figure out the issue or getting issue at other places, lets try this.
You need to save session variable outside method scope (make it a instance variable). Since you defined it locally in function scope. Its get deallocated before completion handler can be called, remember completion handler can't retain your session object and after execution of run loop, garbage collector will dealloc your session object. We need to retain such objects whenever we want call back from delegates or from completion handler..
self.session = URLSession(configuration: URLSessionConfiguration.default)
Did the changes suggested here, It works now.
Using NSURLSession from a Swift command line program
var sema = DispatchSemaphore( value: 0 )
private func execTask(request: URLRequest, taskCallback: #escaping (Bool,
AnyObject?) -> ()) {
let session = URLSession(configuration: URLSessionConfiguration.default, delegate: self, delegateQueue: nil )
session.dataTask(with: request) {(data, response, error) -> Void in
if let data = data {
let json = try? JSONSerialization.jsonObject(with: data, options: [])
if let response = response as? HTTPURLResponse , 200...299 ~= response.statusCode {
taskCallback(true, json as AnyObject?)
} else {
taskCallback(false, json as AnyObject?)
}
}
}.resume()
sema.wait()
}
let dataTask = session.dataTask(with: request, completionHandler: {data, response,error -> Void in
print("Request : \(response)")
let res = response as! HTTPURLResponse
print("Status Code : \(res.statusCode)")
let strResponse = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print("Response String :\(strResponse)")
})
dataTask.resume()
Swift 3.0
Just copy below code into your view controller.
#IBAction func btnNewApplicationPressed (_ sender: UIButton) {
callWebService()
}
func callWebService() {
// Show MBProgressHUD Here
var config :URLSessionConfiguration!
var urlSession :URLSession!
config = URLSessionConfiguration.default
urlSession = URLSession(configuration: config)
// MARK:- HeaderField
let HTTPHeaderField_ContentType = "Content-Type"
// MARK:- ContentType
let ContentType_ApplicationJson = "application/json"
//MARK: HTTPMethod
let HTTPMethod_Get = "GET"
let callURL = URL.init(string: "https://itunes.apple.com/in/rss/newapplications/limit=10/json")
var request = URLRequest.init(url: callURL!)
request.timeoutInterval = 60.0 // TimeoutInterval in Second
request.cachePolicy = URLRequest.CachePolicy.reloadIgnoringLocalCacheData
request.addValue(ContentType_ApplicationJson, forHTTPHeaderField: HTTPHeaderField_ContentType)
request.httpMethod = HTTPMethod_Get
let dataTask = urlSession.dataTask(with: request) { (data,response,error) in
if error != nil{
return
}
do {
let resultJson = try JSONSerialization.jsonObject(with: data!, options: []) as? [String:AnyObject]
print("Result",resultJson!)
} catch {
print("Error -> \(error)")
}
}
dataTask.resume()
}
Sometimes, for me, the solution when completionHandler were not called in these cases was because the flag "Allow Arbitrary loads" on Info.plist was defined as NO.
Allow Arbitrary loads flag defined as YES
I am currently trying to download, parse and print JSON from an URL.
So far I got to this point:
1) A class (JSONImport.swift), which handles my import:
var data = NSMutableData();
let url = NSURL(string:"http://headers.jsontest.com");
var session = NSURLSession.sharedSession();
var jsonError:NSError?;
var response : NSURLResponse?;
func startConnection(){
let task:NSURLSessionDataTask = session.dataTaskWithURL(url!, completionHandler:apiHandler)
task.resume();
self.apiHandler(data,response: response,error: jsonError);
}
func apiHandler(data:NSData?, response:NSURLResponse?, error:NSError?)
{
do{
let jsonData : NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary;
print(jsonData);
}
catch{
print("API error: \(error)");
}
}
My problem is, that the data in
do{
let jsonData : NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary;
print(jsonData);
}
remains empty.
When I debug,the connection starts successfully, with the given url as a parameter. But my jsonData variable doesn't get printed. Instead the catch block throws the error, stating that there is no data in my variable:
API error: Error Domain=NSCocoaErrorDomain Code=3840 "No value."
Can someone please help me with this?
What am I missing?
Thank you all very much in advance!
[Edited after switching from NSURL Connection to NSURLSession]
Here's an example on how to use NSURLSession with a very convenient "completion handler".
This function contains the network call and has the "completion handler" (a callback for when the data will be available):
func getDataFrom(urlString: String, completion: (data: NSData)->()) {
if let url = NSURL(string: urlString) {
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithURL(url) { (data, response, error) in
// print(response)
if let data = data {
completion(data: data)
} else {
print(error?.localizedDescription)
}
}
task.resume()
} else {
// URL is invalid
}
}
You can use it like this, inside a new function, with a "trailing closure":
func apiManager() {
getDataFrom("http://headers.jsontest.com") { (data) in
do {
let json = try NSJSONSerialization.JSONObjectWithData(data, options: [])
if let jsonDict = json as? NSDictionary {
print(jsonDict)
} else {
// JSON data wasn't a dictionary
}
}
catch let error as NSError {
print("API error: \(error.debugDescription)")
}
}
}
Im having an issue, I am trying to create a method which accepts a PFObject as a parameter. The PFObject in this case is the facebook picture URL. The method takes the URL and basically converts it into an image. I can get it to work if i just use this block of code without trying to make it into a method, however I would like to create a method out of this so that I dont have to keep repeating myself. When i try to return the users image i keep getting the error cannot convert the expressions type UIImage to type void swift
Here is the code
func downloadFBUserImage(object: PFObject?) -> UIImage? {
var userProfilePhotoURLString = object?.valueForKey("pictureURL") as String?
if userProfilePhotoURLString != nil {
var pictureURL: NSURL = NSURL(string: userProfilePhotoURLString!)!
var urlRequest: NSURLRequest = NSURLRequest(URL: pictureURL)
NSURLConnection.sendAsynchronousRequest(urlRequest, queue: NSOperationQueue.mainQueue(), completionHandler: { (NSURLResponse response, NSData data, NSError error) -> Void in
if error == nil && data != nil {
var userProfilePic: UIImage? = UIImage(data: data)
return userProfilePic
}
})
return nil
}
The error is reporting that the completionHandler of the sendAsynchronousRequest is defined to pass you the response, data, and error objects, but that it expects that completionHandler, itself, to not return any values. But you're trying to return a value from within that completionHandler closure.
Bottom line, you cannot simply return the UIImage from your function, because you are performing asynchronous method (i.e. the data is returned later even though you return from the function immediately). So, employ asynchronous pattern:
func downloadFBUserImage(object: PFObject?, completionHandler: (UIImage?, NSError?) -> Void) {
if let userProfilePhotoURLString = object?.valueForKey("pictureURL") as? String {
let pictureURL = NSURL(string: userProfilePhotoURLString)!
let urlRequest = NSURLRequest(URL: pictureURL)
NSURLConnection.sendAsynchronousRequest(urlRequest, queue: NSOperationQueue.mainQueue()) { (response, data, error) -> Void in
if data != nil {
var userProfilePic = UIImage(data: data)
completionHandler(userProfilePic, nil)
} else {
completionHandler(nil, error)
}
}
}
}
And you'd call it using the same completion handler pattern that sendAsynchronousRequest does:
downloadFBUserImage(object) { image, error in
if image == nil {
println(error)
} else {
// use the image here
}
}
// but don't try to use asynchronously retrieved image here
You cannot return to the completion block like that. The completion block does not have a return parameter. This is why you are getting an error.
For updating the image after download, you can pass in a block along with your downloadFBUserImage function like below.
I used dispatch_async because UI updates have to be done on the main thread.
func downloadFBUserImage(object: PFObject?, completion completionBlock:(UIImage) -> ()) -> (){
var userProfilePhotoURLString = object?.valueForKey("pictureURL") as String?
if userProfilePhotoURLString != nil {
var pictureURL: NSURL = NSURL(string: userProfilePhotoURLString!)!
var urlRequest: NSURLRequest = NSURLRequest(URL: pictureURL)
NSURLConnection.sendAsynchronousRequest(urlRequest, queue: NSOperationQueue.mainQueue(), completionHandler: { (NSURLResponse response, NSData data, NSError error) -> Void in
if error == nil && data != nil {
if let userProfilePic = UIImage(data: data) {
completionBlock(userProfilePic)
}
}
})
}
}
It can be called like this
func do() {
downloadFBUserImage(pfObject, completion: { (image) -> () in
//updateImage
dispatch_async(dispatch_get_main_queue(), { () -> Void in
// UI updates
}
})
}
I'm calling to refresh label after refreshQuote() function finishes. When look at the log to see what happened with label.text I can see it has been replaced however the view still looks the same.
Im calling refreshQuote() from viewDidload.
When calling setQuoteLabel directly from viewDidLoad it all works fine
Please help, loosing hope now.
Thanks in advance
func refreshQuote()
{
var url : String = "https://api.parse.com/1/classes/Quotes"
var request : NSMutableURLRequest = NSMutableURLRequest()
request.addValue("------", forHTTPHeaderField: "X-Parse-Application-Id")
request.addValue("------strong text", forHTTPHeaderField: "X-Parse-REST-API-Key")
request.URL = NSURL(string: url)
request.HTTPMethod = "GET"
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
NSLog(error.debugDescription);
let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
if (jsonResult != nil)
{
var allResults: NSArray = jsonResult["results"] as NSArray
var pickedResult: NSDictionary = allResults[0] as NSDictionary
let q:String = pickedResult["message"] as String!
self.setQuoteLabel(q);
} else
{
// couldn't load JSON, look at error
}
})
}
func setQuoteLabel (quote:String)
{
NSLog(quote)
quoteLabel.text = quote;
quoteLabel.setNeedsDisplay();
NSLog(quoteLabel.text!)
}
All UI components must be updated from the main thread, whereas in your case you are updating most likely from a different thread, because the code is in an asynchronous block.
To force a block of code to be executed in the main thread, you can use dispatch_async as follows:
dispatch_async (dispatch_get_main_queue ()) {
self.setQuoteLabel(q)
}