func get_data_from_server() {
let urlPath = NSString(format:"url")
var url: NSURL = NSURL(string: urlPath)!
let data : NSData = NSData(contentsOfURL: url)!
var error: NSErrorPointer = nil
var jsonResult: AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
if (jsonResult != nil) {
if let image_id_array : NSArray! = jsonResult?.valueForKey("Result")?.valueForKey("id") as? NSArray {
self.id_array = image_id_array
}
if let description_Array = jsonResult?.valueForKey("Result")?.valueForKey("description") as? NSArray {
self.description_array = description_Array
}
if let img_array = jsonResult?.valueForKey("Result")?.valueForKey("image") as? NSArray {
self.images_array = img_array
}
}
}
How to use dispatch_async in swift. I'd like to load an image from a URL in my application
Add the whole method of downloading images and add it to array in the following box:
dispatch_async(dispatch_get_main_queue()) {
// add you code here
}
You should write your code to load your image from a URL like this
cell.imageView.image = [UIImage imageNamed:#"default_icon"];
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
NSData *data = [NSData dataWithContentsOfURL:imageURL];
UIImage *image = [UIImage imageWithData:data];
dispatch_async(dispatch_get_main_queue(), ^{
cell.imageView.image = image;
});
});
you should use main queue for change UI only not for Download image.
Try like this for async request...
let url = NSURL(string:"http://juzhotel.com/smartcreatives/catholic_app/app/index.php/webservices/getCatholicHighlight")
let request = NSMutableURLRequest(URL: url!)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue())
{
(response, data, error) in
if let HTTPResponse = response as? NSHTTPURLResponse {
let statusCode = HTTPResponse.statusCode
if statusCode == 200 {
// Yes, Do something.
let resstr = NSString(data: data, encoding: NSUTF8StringEncoding)
println("Data Reriving %#",resstr)
}
}
}
Its working fine in my code
Related
I have found learning swift to be more or less unbearable to do anything, something that would be done in a single line in Python becomes a whole task in swift.
I am trying to return the data from a http request and cannot find a single source that explains how. The only things I can find prints the data instead of returning it, either as a dictionary (from using JSONSerialization) or simply as a string.
let url = URL(string: "url")!
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if let error = error {
print("error: \(error)")
} else {
if let response = response as? HTTPURLResponse {
print("statusCode: \(response.statusCode)")
}
if let data = data, let dataString = String(data: data, encoding: .utf8) {
print("data: \(dataString)")
}
}
}
task.resume()
func makePostRequest(){
let urlPath: String = "http://www.swiftdeveloperblog.com/http-post-example- script/"
var url: NSURL = NSURL(string: urlPath)!
var request: NSMutableURLRequest = NSMutableURLRequest(URL: url)
request.HTTPMethod = "POST"
var stringPost="firstName=James&lastName=Bond" // Key and Value
let data = stringPost.dataUsingEncoding(NSUTF8StringEncoding)
request.timeoutInterval = 60
request.HTTPBody=data
request.HTTPShouldHandleCookies=false
let queue:NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary
if (jsonResult != nil) {
// Success
println(jsonResult)
let message = jsonResult["Message"] as! NSString
println(message)
}else {
// Failed
println("Failed")
}
})
}
I make some code using swift 4 to load image from URL, but every time I add images to server, it took a lot of time to load it in colection view or table view. I want to try store it in NScache but i dont understand to do it. can anyone help me, I'm new in swift :(
#objc func loadPosts() {
let url = URL(string: "http://someURL/Url.php")!
var request = URLRequest(url: url)
request.httpMethod = "POST"
let body = "phomepost=\(homepost)"
request.httpBody = body.data(using: String.Encoding.utf8)
URLSession.shared.dataTask(with: request) { data, response, error in
DispatchQueue.main.async(execute: {
if error == nil {
do{
let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
self.comments.removeAll(keepingCapacity: false)
self.images.removeAll(keepingCapacity: false)
self.collectionView?.reloadData()
guard let parseJSON = json else {
print("Error While Parsing")
return
}
guard let posts = parseJSON["posts"] as? [AnyObject] else {
print("Error while parseJSONing")
return
}
self.comments = posts.reversed()
for i in 0 ..< self.comments.count {
let path = self.comments[i]["path"] as? String
if !path!.isEmpty {
let url = NSURL(string: path!)!
let imageData = try? Data(contentsOf: url as URL)
let image = UIImage(data: imageData! as Data)!
self.images.append(image)
} else {
let image = UIImage()
self.images.append(image)
}
}
self.collectionView?.reloadData()
//print(posts.count)
} catch {
print(error)
}
}else{
print(error)
}
})
}.resume()
}
You can use something like this:
private let cache = NSCache<NSString, NSData>()
.....
func downloadImage(url: String, handler: #escaping(Data?, Error?) -> Void){
let cacheID = NSString(string: url)
if let cachedData = cache.object(forKey: cacheID) {
handler((cachedData as Data), nil)
}else{
if let url = URL(string: url) {
let session = URLSession(configuration: urlSessionConfig)
var request = URLRequest(url: url)
request.cachePolicy = .returnCacheDataElseLoad
request.httpMethod = "get"
session.dataTask(with: request) { (data, response, error) in
if let _data = data {
self.cache.setObject(_data as NSData, forKey: cacheID)
handler(_data, nil)
}else{
handler(nil, error)
}
}.resume()
} else {
// NetworkError is a custom error
handler(nil, NetworkError.invalidURL)
}
}
}
}
This will add a small animation while loading using image set.
let imageCache = NSCache<AnyObject, AnyObject>()
extension UIImageView {
func loadImageFromUrl(urlString: String) {
let loader1 = UIImage(named: "loaderImage1.png")
let loader2 = UIImage(named: "loaderImage2.png")
let loader3 = UIImage(named: "loaderImage3.png")
let imageArray = [loader1, loader2, loader3]
let animatedImage = UIImage.animatedImage(with: imageArray as! [UIImage], duration: 1.7)
if let imageFromCache = imageCache.object(forKey: urlString as AnyObject) as? UIImage{
self.image = imageFromCache
return
} else {
self.image = animatedImage
Alamofire.request(urlString, method: .get).response { (responseData) in
if let data = responseData.data {
DispatchQueue.main.async {
if let imageToCache = UIImage(data: data){
imageCache.setObject(imageToCache, forKey: urlString as AnyObject)
self.image = imageToCache
}
}
}
} //alamofire
}
}
}
I have UIImageView and I want to download images in cache if exist, I've used extension func.
I have this code but not working:
extension UIImageView {
func loadImageUsingCache (_ urlString : String) {
let imageCache = NSCache<AnyObject, AnyObject>()
if let cachedImage = imageCache.object(forKey: urlString as AnyObject) {
self.image = cachedImage as? UIImage
return
}
let url = URL(string: urlString)
URLSession.shared.dataTask(with: url!) { (data, response, error) in
if data != nil {
if let image = UIImage(data: data!) {
imageCache.setObject(image, forKey: urlString as AnyObject)
DispatchQueue.main.async(execute: {
self.image = image
})
}
}
}.resume()
}
}
You're creating the new NSCache object for each image and not retain it.
You should create object variable instead of local one. It won't work in extension in this case. Also you can try to use URLCache.shared instead.
// It's Perfect Solution //
var imageCache = String: UIImage
class CustomImageView: UIImageView {
var lastImgUrlUsedToLoadImage: String?
func loadImage(with urlString: String) {
// set image to nil
self.image = nil
// set lastImgUrlUsedToLoadImage
lastImgUrlUsedToLoadImage = urlString
// check if image exists in cache
if let cachedImage = imageCache[urlString] {
self.image = cachedImage
return
}
// url for image location
guard let url = URL(string: urlString) else { return }
// fetch contents of URL
URLSession.shared.dataTask(with: url) { (data, response, error) in
// handle error
if let error = error {
print("Failed to load image with error", error.localizedDescription)
}
if self.lastImgUrlUsedToLoadImage != url.absoluteString {
return
}
// image data
guard let imageData = data else { return }
// create image using image data
let photoImage = UIImage(data: imageData)
// set key and value for image cache
imageCache[url.absoluteString] = photoImage
// set image
DispatchQueue.main.async {
self.image = photoImage
}
}.resume()
}
}
I have a function that is loading a pic of the user from URL that is using this UIImageView extension:
let imageCache = NSCache<AnyObject, AnyObject>()
extension UIImageView {
func loadImageUsingCacheWithUrlString(urlString: String) {
self.image = nil
print("here the URL of the image", urlString)
//check cache for image first
if let cachedImage = imageCache.object(forKey: urlString as AnyObject) {
self.image = cachedImage as? UIImage
return
}
// otherwise fire off a new download
let url = URL(string: urlString)
URLSession.shared.dataTask(with: url!, completionHandler: { (data, response, error) in
if error != nil {
print(error!)
return
}
DispatchQueue.main.async {
if let downloadedImage = UIImage(data: data!) {
imageCache.setObject(downloadedImage, forKey: urlString as AnyObject)
self.image = downloadedImage
}
}
}).resume()
}
}
Now, the problem I have is, that sometimes the the profile picture is loaded and sometimes not. I suppose that this happen because the function download the image asynchronously, but why once it's downloaded it doesn't appear On the profile?
I'm calling it with:
if hostPerfil != nil {
if let photo = hostPerfil?.picture {
hostPic.loadImageUsingCacheWithUrlString(urlString: photo)
}
hostName.text = hostPerfil!.firstName
}
What am I doing wrong? Can anyone help me with this, please?
When you get the image from your imageCache, you need to set the image of the UIImageView within the main UI thread so that it will be rendered properly. You did that when you download it, that is why it is displaying, but you have to do it as well when you are getting it from cache.
DispatchQueue.main.async {
if let cachedImage = imageCache.object(forKey: urlString as AnyObject) {
self.image = cachedImage as? UIImage
return
}
}
I am new to swift.
I have one code. It encode a local image logo.png to NSData.
let testImage = NSData(contentsOfFile: NSBundle.mainBundle().pathForResource("logo", ofType: "png")!)
How to encode an image from a URL to NSData?
Replace myURL with the required URL:
let testImage = NSData(contentsOfURL: myURL)
Try this one :-
var image: UIImage?
let imgURL = NSURL(string: "\(yourURL)")
let request: NSURLRequest = NSURLRequest(URL: imgURL!)
let mainQueue = NSOperationQueue.mainQueue()
NSURLConnection.sendAsynchronousRequest(request, queue: mainQueue, completionHandler: { (response, data, error) -> Void in
if error == nil {
// Convert the downloaded data in to a UIImage object
image = UIImage(data: data!)
} else {
image = UIImage(named: "JobPlaceholder") // if occurred an error put a placeholder image
}
})
I have done in swift 3.3 and 4. But this will hang UI and result in jerk.
do {
let imgData = try NSData(contentsOf: URL.init(string: "SomeUrl")!, options: NSData.ReadingOptions())
let image = UIImage(data: imgData as Data)
DispatchQueue.main.async() { () -> Void in
completionBlock(image)
}
} catch {
}
You can also pass image url to dataTask method of URLSession and get data in response. This is best way to avoid jerk in UI. Like below
if let url = URL(string: "someUrl") {
URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
let mimeType = response?.mimeType, mimeType.hasPrefix("image"),
let data = data, error == nil,
let image = UIImage(data: data) else {
DispatchQueue.main.async() { () -> Void in
completionBlock(nil)
}
return
}
DispatchQueue.main.async() { () -> Void in
completionBlock(image)
}
}.resume()
}
This one is working in Swift 3.0 Replace the contentsof:forcastURL with contentsOf: forecastURL! as URL
let forecastURL = NSURL(string: "http://photos.state.gov/libraries/media/788/images/90x90.gif")
let testImage = NSData (contentsOf: forecastURL! as URL)
print("data",testImage!)
let image = UIImage(data: testImage! as Data)
print("imaGE :-",image!)