Im trying to update my basic weather app i made with swift 2 to swift 3 this is my code:
func getWeather(city: String) {
let path = "http://api.openweathermap.org/data/2.5/weather?q=London,uk&appid=095711373620570aa92ee530246dc8af"
let url = NSURL(string: path)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithURL(url!) { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
print(">>>> \(data)")
}
and NSURLSession.sharedSession(5th line) and NSURLResponse(6th line) print out an error
Don't annotate types in the completion handler signature and use the Swift 3 native structures:
func getWeather(city: String) {
let path = "http://api.openweathermap.org/data/2.5/weather?q=London,uk&appid=095711373620570aa92ee530246dc8af"
let url = URL(string: path)
let session = URLSession.shared
let task = session.dataTask(with:url!) { (data, response, error) -> Void in
print(">>>> \(data)")
}
Swift 3 update
URLSession.shared.dataTask()
Related
I'm writing a CLI tool in Swift 4 for MacOS.
If I "cheat" and use a shell function, then the curl command, I get exactly the result I'm after:
func shell(_ args: String...) -> Int32 {
let task = Process()
task.launchPath = "/usr/bin/env"
task.arguments = args
task.launch()
task.waitUntilExit()
return task.terminationStatus
}
shell("/usr/bin/curl", "-OL", "http://mywebserver/myfile.whatever")
How do I do the same thing natively in Swift 4?
I tried using the just library: https://github.com/dduan/Just
but I can't figure out how to simply get it to download a file from a URL to a specific location on the file system.
I've also found various solutions for Swift 3 and 5, and iOS which obviously don't work for me.
Simple example: Due to the asynchronous behavior of URLSession you have to start the runloop after resuming the data task and stop it in the completion handler.
let runLoop = CFRunLoopGetCurrent()
let url = URL(string: "http://mywebserver/myfile.whatever")!
let dataTask = URLSession.shared.dataTask(with: url) { data, response, error in
let returnValue : Int32
if let error = error {
fputs("\(error.localizedDescription)\n", stderr)
returnValue = EXIT_FAILURE
} else {
let result = String(data:data!, encoding:.utf8)!
fputs("\(result)\n", stdout)
returnValue = EXIT_SUCCESS
}
CFRunLoopStop(runLoop)
exit(returnValue)
}
dataTask.resume()
CFRunLoopRun()
The code returns the data in stdout. You can write the data directly to disk, replace
let result = String(data:data!, encoding:.utf8)!
fputs("\(result)\n", stdout)
with
let fileURL = URL(fileURLWithPath: "/Users/me/path/to/file.ext")
do {
try data!.write(to: fileURL)
} catch {
fputs("\(error.localizedDescription)\n", stderr)
}
You can download using downloadTask
Create session configuration
Create URLSession with this configuration
Apply download task
When the download is done successfully, copy the data to the destination
let documentsUrl:URL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first as URL!
let destinationFileUrl = documentsUrl.appendingPathComponent("downloadedFile.jpg")
//Create URL to the source file you want to download
let fileURL = URL(string: "https://en.wikipedia.org/wiki/Saint_Martin#/media/File:Saint_martin_map.PNG")
let sessionConfig = URLSessionConfiguration.default
let session = URLSession(configuration: sessionConfig)
let request = URLRequest(url:fileURL!)
let task = session.downloadTask(with: request) { (tempLocalUrl, response, error) in
if let tempLocalUrl = tempLocalUrl, error == nil {
// Success
if let statusCode = (response as? HTTPURLResponse)?.statusCode {
print("Successfully downloaded. Status code: \(statusCode)")
}
do {
try FileManager.default.copyItem(at: tempLocalUrl, to: destinationFileUrl)
} catch (let writeError) {
print("Error creating a file \(destinationFileUrl) : \(writeError)")
}
} else {
print("Error took place while downloading a file. Error description: %#", error?.localizedDescription);
}
}
task.resume()
}
I have this vanilla piece of code I virtually use everywhere in my code:
let configuration = URLSessionConfiguration.default
let session = URLSession(configuration:configuration)
let listTask = session.dataTask(with: theRequest, completionHandler: {[weak self](data, response, error) in
})
Yet in one particular class the compiler complaints:
Cannot invoke 'dataTask' with an argument list of type '(with:
URLRequest, completionHandler: (Data?, URLResponse?, Error?) -> ())'
Expected an argument list of type '(with: URLRequest, completionHandler: > (Data?, URLResponse?, Error?) -> Void)'
How does it infer the return value of the closure to be () instead of the expected Void? I copied the code from other classes repeatedly lest I wrote something wrongly.
For some reason adding:
return ()
at the end of the closure, as suggested on the Apple forum, fixed the issue.
tried in xcode 8 beta 6 with swift 3 playground
let configuration = URLSessionConfiguration.default
let session = URLSession(configuration:configuration)
let theRequest = URLRequest(url: URL(string: "")!)
let task = session.dataTask(with: URL(string: "")!) { (data:Data?, response:URLResponse?, error:Error?) in
}
let task1 = session.dataTask(with: theRequest) { (data:Data?, response:URLResponse?, error:Error?) in
}
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
When I use the code below for my swift 2 xcode 7 project using parse 1.8.5 sdk, I get the error "use of undeclared type 'FBRequest' " in the first line. I downloaded the last facebook and parse frameworks. Why am I getting this error?
let request:FBRequest = FBRequest.requestForMe()
request.startWithCompletionHandler { (connection:FBRequestConnection!, result:AnyObject!, error:NSError!) -> Void in
if error == nil{
if let dict = result as? Dictionary<String, AnyObject>{
let name:String = dict["name"] as AnyObject? as String
let facebookID:String = dict["id"] as AnyObject? as String
let email:String = dict["email"] as AnyObject? as String
let pictureURL = "https://graph.facebook.com/\(facebookID)/picture?type=large&return_ssl_resources=1"
var URLRequest = NSURL(string: pictureURL)
var URLRequestNeeded = NSURLRequest(URL: URLRequest!)
NSURLConnection.sendAsynchronousRequest(URLRequestNeeded, queue: NSOperationQueue.mainQueue(), completionHandler: {(response: NSURLResponse!,data: NSData!, error: NSError!) -> Void in
if error == nil {
var picture = PFFile(data: data)
PFUser.currentUser().setObject(picture, forKey: "profilePicture")
PFUser.currentUser().saveInBackground()
}
else {
println("Error: \(error.localizedDescription)")
}
})
PFUser.currentUser().setValue(name, forKey: "username")
PFUser.currentUser().setValue(email, forKey: "email")
PFUser.currentUser().saveInBackground()
}
}
I am using the frameworks below:
import FBSDKCoreKit
import FBSDKLoginKit
import FBSDKShareKit
import ParseFacebookUtilsV4
There is no FBRequest in Facebook iOS SDK 4.x. Use FBSDKGraphRequest instead. You can read more about migration from Facebook iOS SDK 3.x to 4.x here.
I am working on a REST API Manager. It is giving an error and I am not able to fix it. The error I got is given below as highlighted.
import Foundation
import Alamofire
import SwiftyJSON
class RestApiManager {
var resources: JSON = [
"resources": [
"resourceA": []
]
]
let apiUrl: String
let apiUsername: String
let apiPassword: String
init(apiUrl: String, apiUsername: String, apiPassword: String) {
self.apiUrl = apiUrl
self.apiUsername = apiUsername
self.apiPassword = apiPassword
getApiResourceA() { responseObject, error in
let resourceA = JSON(responseObject!)
self.resources["resources"]["resourceA"] = resourceA
}
}
func collectDataFromApi(completionHandler: (responseObject: NSDictionary?, error: NSError?) -> ()) {
prepareHttpRequest(completionHandler)
}
func prepareHttpRequest(completionHandler: (responseObject: NSDictionary?, error: NSError?) -> ()) {
let alamofireRequest = Alamofire.request(.GET, "\(self.apiUrl)")
alamofireRequest.authenticate(user: self.apiUsername, password: self.apiPassword)
alamofireRequest.responseJSON { request, response, responseObject, error in
completionHandler(responseObject: responseObject as? NSDictionary, error: error)
}
}
func getAllResources() -> JSON {
return self.resources
}
func getApiResourceA(completion: (responseObject: NSDictionary?, error: NSError?) -> ()) {
collectDataFromApi() { responseObject, error in
completion(responseObject: responseObject, error: error)
}
}
}
And when I call this class to get the resources:
override func viewDidLoad() {
super.viewDidLoad()
if record != nil {
let url = record?.url
let username = record?.username
let password = record?.password
let restApiManager = RestApiManager(apiUrl: url!, apiUsername: username!, apiPassword: password!) // This line seems buggy
let delay = 10.0 * Double(NSEC_PER_SEC)
let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
dispatch_after(time, dispatch_get_main_queue()) {
let Resources = restApiManager.getAllResources()
let ResourceA = Resources["resources"]["resourceA"]
}
}
}
The line I commented prints:
Thread 1: breakpoint 2.1
I need suggestions for fix that error. Any suggestions are very much appreciated
You may have accidentally set a breakpoint without noticing.
Click and drag the blue tick representing the breakpoint outside of the gutter to erase it.
I was getting same error when I accidentally activated Breakpoint in my Xcode.
To resolve issue, simply unblock blue icon.