I'm trying to download an image from a url in swift. This is the image url I'm trying to download, and I'm expecting it to download it to On my iPhone > testExampleApplication in the application's documents directory, but when I click the button, nothing downloads. Here's my code:
Button("Download logo image") {
let imageUrlStr = "https://media.wired.com/photos/5f2d7c2191d87e6680b80936/16:9/w_2400,h_1350,c_limit/Science_climatedesk_453801484.jpg".addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!
let task = URLSession.shared.dataTask(with: URLRequest(url: URL(string: imageUrlStr)!), completionHandler: {(data, response, error) -> Void in
print("download details 1: \(data)")
print("download details 2: \(response)")
print("download details 3: \(error)")
})
// Start the download.
task.resume()
}
The Content-type in the 2nd print is image/jpeg and the error print is nil.
Am I doing something wrong in my downloading code?
In general, it's a good idea to do asynchronous tasks like this in a ObservableObject rather than the View itself.
You're already doing the downloading -- all you need to do now is save the data:
class Downloader : ObservableObject {
func downloadImage() {
let imageUrlStr = "https://media.wired.com/photos/5f2d7c2191d87e6680b80936/16:9/w_2400,h_1350,c_limit/Science_climatedesk_453801484.jpg".addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!
let task = URLSession.shared.dataTask(with: URLRequest(url: URL(string: imageUrlStr)!), completionHandler: {(data, response, error) -> Void in
guard let data = data else {
print("No image data")
return
}
do {
try data.write(to: self.getDocumentsDirectory().appendingPathComponent("image.jpg"))
print("Image saved to: ",self.getDocumentsDirectory())
} catch {
print(error)
}
})
// Start the download.
task.resume()
}
private func getDocumentsDirectory() -> URL {
let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
return paths[0]
}
}
struct ContentView : View {
#StateObject private var downloader = Downloader()
var body : some View {
Button("Download") {
downloader.downloadImage()
}
}
}
If you run this in the simulator, you can see the output to the console with the location of the directory. If you open that in Finder, you'll see your image has been saved there.
Note that to see the directory and file in the Files app, you'll need to make sure that you've set UIFileSharingEnabled to YES in your Info.plist
Firstly import Kingfisher as-
pod 'Kingfisher'
Then import it in your class as -
import Kingfisher
After that add a temporary UIImageView
let imgView = UIImageView()
imgView.kf.setImage(with: yourImageURL)
if let finalImage = imgView.image {
// finalImage is your image
}
This question already has answers here:
Loading/Downloading image from URL on Swift
(39 answers)
Closed 3 years ago.
I am trying to load image from url in my ios app swift. I have written following code.
let imageURL = minHost + "\(userData["profileImage"])"
let url = URL(string: imageURL)!
let imageData = try? Data(contentsOf: url)
profileImage.image = UIImage(data: imageData!)
Now imageURL is having proper url, but imageData receives nil and because of this, last line through an error Fatal error: Unexpectedly found nil while unwrapping an Optional value
Instead of fetching image using Data(contentsOf:) method, use URLSession to perform network calls.
let imageURL = minHost + "\(userData["profileImage"])"
if let url = URL(string: imageURL) {
URLSession.shared.dataTask(with: url) {[weak self] (data, urlResponse, error) in
if let data = data {
DispatchQueue.main.async {
self?.profileImage.image = UIImage(data: imageData)
}
}
}.resume()
}
Important Note: Avoid using forced unwrapping (!) unnecessarily. It might result in unwanted app crashes. Instead use guard or if-let to unwrap optionals.
Try this at Playground.
Loading image from the URL takes some time, and need to be executed at another Thread, different from the main thread.
import UIKit
let url = URL(string: "https://cdn.arstechnica.net/wp-content/uploads/2018/06/macOS-Mojave-Dynamic-Wallpaper-transition.jpg")!
var image = UIImage()
DispatchQueue.global().async {
if let data = try? Data(contentsOf: url) {
DispatchQueue.main.async {
image = UIImage(data: data)!
}
}
}
image
you can try like this:
let url = URL(string: "image url here")
if url != nil {
DispatchQueue.global().async { [weak self] in
if let data = try? Data(contentsOf: url!) {
if let image = UIImage(data: data) {
DispatchQueue.main.async {
self.profileImage.image = image
}
}
}
}
}
Try This
let url = URL(string:imageURL)
if let data = try? Data(contentsOf: url!)
{
profileImage.image = UIImage(data: data, scale: 1.0)!
}
Never do the downloading task on main thread. if you do, you will not able to access components in current visible screens properly. It should be always on the background thread.
if let url = URL(string: "https://....") {
DispatchQueue.global(qos: .background).async {
if let data = try? Data(contentsOf: url) {
if let image = UIImage(data: data) {
DispatchQueue.main.async {
self.profileImage.image = image
}
}
}
}
}
I am a fairly decent Objective C developer, and I am now learning Swift (of which I am finding quite difficult, not only because of new concepts, such as optionals, but also because Swift is continually evolving, and much of the available tutorials are severely outdated).
Currently I am trying parse a JSON from a url into an NSDictionary and then use one of its value to display an image (which is also a url). Something like this:
URL -> NSDictionary -> init UIImage from url -> display UIImage in UIImageView
This is quite easy in Objective C (and there may even be a shorter answer):
NSURL *url = [NSURL URLWithString:#"https://api.nasa.gov/planetary/apod?api_key=DEMO_KEY"];
NSData *apodData = [NSData dataWithContentsOfURL:url];
NSDictionary *apodDict = [NSJSONSerialization JSONObjectWithData:apodData options:0 error:nil];
The above code snippet gives me back a standard NSDictionary, in which I can refer to the "url" key to get the address of the image I want to display:
"url" : "https://apod.nasa.gov/apod/image/1811/hillpan_apollo15_4000.jpg"
This I then convert into a UIImage and give it to a UIImageView:
NSURL *imageURL = [NSURL URLWithString: [apodDict objectForKey:#"url"]];
NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
UIImage *apodImage = [UIImage imageWithData:imageData];
UIImageView *apodView = [[UIImageView alloc] initWithImage: apodImage];
Now, I am basically trying to replicate the above Objective C code in Swift but continuously run into walls. I have tried several tutorials (one of which actually did the exact same thing: display a NASA image), as well as find a few stack overflow answers but none could help because they are either outdated or they do things differently than what I need.
So, I would like to ask the community to provide the Swift 4 code for the these problems:
1. Convert data from url into a Dictionary
2. Use key:value pair from dict to get url to display an image
If it is not too much already, I would also like to ask for detailed descriptions alongside the code because I would like the answer to be the one comprehensive "tutorial" for this task that I believe is currently not available anywhere.
Thank you!
First of all I'm pretty sure that in half a year you will find Objective-C very complicated and difficult. 😉
Second of all even your ObjC code is discouraged. Don't load data from a remote URL with synchronous Data(contentsOf method. Regardless of the language use an asynchronous way like (NS)URLSession.
And don't use Foundation collection types NSArray and NSDictionary in Swift. Basically don't use NS... classes at all if there is a native Swift counterpart.
In Swift 4 you can easily decode the JSON with the Decodable protocol directly into a (Swift) struct,
the URL string can be even decoded as URL.
Create a struct
struct Item: Decodable {
// let copyright, date, explanation: String
// let hdurl: String
// let mediaType, serviceVersion, title: String
let url: URL
}
Uncomment the lines if you need more than the URL.
And load the data with two data tasks.
let url = URL(string: "https://api.nasa.gov/planetary/apod?api_key=DEMO_KEY")!
let task = URLSession.shared.dataTask(with: url) { (data, _, error) in
if let error = error { print(error); return }
do {
let decoder = JSONDecoder()
// this line is only needed if all JSON keys are decoded
decoder.keyDecodingStrategy = .convertFromSnakeCase
let result = try decoder.decode(Item.self, from: data!)
let imageTask = URLSession.shared.dataTask(with: result.url) { (imageData, _, imageError) in
if let imageError = imageError { print(imageError); return }
DispatchQueue.main.async {
let apodImage = UIImage(data: imageData!)
let apodView = UIImageView(image: apodImage)
// do something with the image view
}
}
imageTask.resume()
} catch { print(error) }
}
task.resume()
You can use this extension
extension UIImage {
public static func loadFrom(url: URL, completion: #escaping (_ image: UIImage?) -> ()) {
DispatchQueue.global().async {
if let data = try? Data(contentsOf: url) {
DispatchQueue.main.async {
completion(UIImage(data: data))
}
} else {
DispatchQueue.main.async {
completion(nil)
}
}
}
}
}
Using
guard let url = URL(string: "http://myImage.com/image.png") else { return }
UIImage.loadFrom(url: url) { image in
self.photo.image = image
}
Since image loading is a trivial and at the same time task which could be implemented in many different ways, I would recommend you to not "reinvent the wheel" and have a look to an image loading library such as Nuke, since it already covers most of the cases you might need during your development process.
It allows you to load and show image asynchronously into your view, using simple api:
Nuke.loadImage(with: url, into: imageView)
And also if you need - to specify how image should be loaded and presented:
let options = ImageLoadingOptions(
placeholder: UIImage(named: "placeholder"),
failureImage: UIImage(named: "failure_image"),
contentModes: .init(
success: .scaleAspectFill,
failure: .center,
placeholder: .center
)
)
Nuke.loadImage(with: url, options: options, into: imageView)
Create an UIIimageView Extension and the following code
extension UIImageView {
public func imageFromServerURL(urlString: String) {
self.image = nil
let urlStringNew = urlString.replacingOccurrences(of: " ", with: "%20")
URLSession.shared.dataTask(with: NSURL(string: urlStringNew)! as URL, completionHandler: { (data, response, error) -> Void in
if error != nil {
print(error as Any)
return
}
DispatchQueue.main.async(execute: { () -> Void in
let image = UIImage(data: data!)
self.image = image
})
}).resume()
}}
and
self.UploadedImageView.imageFromServerURL(urlString: imageURLStirng!)
I have just extended on vadian's answer, separated some concerns to clearly understand the basics. His answer should suffice.
First, you have to build your structure. This will represent the JSON structure you retrieved from the webservice.
struct Item: Codable {
let url, hdurl : URL,
let copyright, explanation, media_type, service_version, title : String
}
Then make you request methods. I usually create a separate file for it. Now, vadian mentioned about completion handlers. These are represented by escaping closures. Here, closure ()-> is passed on both functions and called having the decoded data as argument.
struct RequestCtrl {
func fetchItem(completion: #escaping (Item?)->Void) {
let url = URL(string: "https://api.nasa.gov/planetary/apod?api_key=DEMO_KEY")!
//URLSessionDataTask handles the req and returns the data which you will decode based on the Item structure we defined above.
let task = URLSession.shared.dataTask(with: url) { (data, _, _) in
let jsonDecoder = JSONDecoder()
if let data = data,
let item = try? jsonDecoder.decode(Item.self, from: data){
//jsonDecoder requires a type of our structure represented by .self and the data from the request.
completion(item)
} else {
completion(nil)
}
}
task.resume()
}
func fetchItemPhoto(usingURL url: URL, completion: #escaping (Data?)-> Void) {
let task = URLSession.shared.dataTask(with: url) { (data, _, _) in
if let data = data { completion(data) } else { completion(nil) }
}
task.resume()
}
}
Now in you ViewController, call your request and handle the execution of your closure.
class ViewController: UIViewController {
let requestCtrl = RequestCtrl()
override func viewDidLoad() {
super.viewDidLoad()
requestCtrl.fetchItem { (fetchedItem) in
guard let fetchedItem = fetchedItem else { return }
self.getPhoto(with: fetchedItem)
}
}
func getPhoto(with item: Item) {
requestCtrl.fetchItemPhoto(usingURL: item.url) { (fetchedPhoto) in
guard let fetchedPhoto = fetchedPhoto else { return }
let photo = UIImage(data: fetchedPhoto)
//now you have a photo at your disposal
}
}
}
These are not the best of practices since I am also still learning, so by all means do some research on topics especially closures, ios concurrency and URLComponents on Apple's documentation :)
you need to convert url into string and data to add in imageview
let imageURL:URL=URL(string: YourImageURL)!
let data=NSData(contentsOf: imageURL)
Yourimage.image=UIImage(data: data! as Data)
First add the pod in Podfile
pod 'Alamofire',
pod 'AlamofireImage'
you can check this link for install pods => https://cocoapods.org/pods/AlamofireImage
// Use this function for load image from URL in imageview
imageView.af_setImage(
withURL: url,
placeholderImage: placeholderImage //its optional if you want to add placeholder
)
Check this link for method of alamofireImage
https://github.com/Alamofire/AlamofireImage/blob/master/Documentation/AlamofireImage%203.0%20Migration%20Guide.md
Update for Xcode 13.3 , Swift 5
To load the Image asynchronously from a URL string, use this extension:
extension UIImageView {
public func getImageFromURLString(imageURLString: String) {
guard let imageURL = URL(string: imageURLString) else { return}
Task {
await requestImageFromURL(imageURL)
}
}
private func requestImageFromURL(_ imageURL: URL) async{
let urlRequest = URLRequest(url: imageURL)
do {
let (data, response) = try await URLSession.shared.data(for: urlRequest)
if let httpResponse = response as? HTTPURLResponse{
if httpResponse.statusCode == 200{
print("Fetched image successfully")
}
}
// Loading the image here
self.image = UIImage(data: data)
} catch let error {
print(error)
}
}
}
Usage:
imageView.getImageFromURLString(imageURLString: "https://apod.nasa.gov/apod/image/1811/hillpan_apollo15_4000.jpg")
I m trying to get Url of image from firebase database and show that url as a image in imageview (iOS).
below is the image of database
How can I do so?
I just started with Xcode, any help will be much appreciated
func showImage() {
Database.database().reference().child("Images").child("abcd").observeSingleEvent(of: .value, with: { snapshot in
if let url = snapshot.value as? String {
URLSession.shared.dataTask(with: URL(string: url)!) { data, response, error in
if error == nil {
let image = UIImage(data: data!)
imageView.image = image
}
}.resume()
}
})
}
I'm just starting to learn how to make network requests in iOS Swift. Below is a very simple image request where everything seems to be working. The task downloads the image with no errors but the imageView never displays the downloaded image. Any help would be greatly appreciated.
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var imageView: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
let imageURL = NSURL(string: "https://en.wikipedia.org/wiki/Baseball#/media/File:Angels_Stadium.JPG")!
let task = NSURLSession.sharedSession().dataTaskWithURL(imageURL) { (data, response, error) in
if error == nil {
let downloadedImage = UIImage(data: data!)
performUIUpdatesOnMain {
self.imageView.image = downloadedImage
}
}
}
task.resume()
}
}
Your code is working fine except for the fact you're using a wrong URL and for that your downloadedImage is coming nil because it can't create an UIImage for this data, the correct URL is:
https://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Angels_Stadium.JPG/1920px-Angels_Stadium.JPG
Update your code code as the above code and everything should be work fine:
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let imageURL = NSURL(string: "https://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Angels_Stadium.JPG/1920px-Angels_Stadium.JPG")!
let task = NSURLSession.sharedSession().dataTaskWithURL(imageURL) { (data, response, error) in
guard error == nil, let data = data else { return }
let downloadedImage = UIImage(data: data)
dispatch_async(dispatch_get_main_queue()) {
self.imageView.image = downloadedImage
}
}
task.resume()
}
I hope this help you.
If you are getting an error from NSURLSession your current code would fail silently. Don't do that.
Add a print statement inside your data task's completion block that logs the value of error and of data. Also log downloadedImage once you convert data to an image.
Finally, show us the code for your performUIUpdatesOnMain function.