Alright so I've made some handlers and classes to grab data from a URL, its all returning fine, I've checked the URLs are valid and everything.
Anyways, I'm trying to do an NSData(contentsOfURL) on a stored URL in my class for a UIViewController. I'm successfully printing out String Variables like name, type, description, but I'm having difficulty displaying an UIImage into a Image View on the ViewController.
Here is my Code, it's run when the View loads:
func configureView() {
// Update the user interface for the detail item.
if let card = detailCard {
title = card.cardTitle
//Assign Elements
detailDescriptionLabel?.text = card.description
typeLabel?.text = card.cardType
cardTitleLabel?.text = card.cardTitle
costLabel?.text = card.cardCost
print(card.cardImageURL)
if let url = NSURL(string: card.cardImageURL){
let data = NSData(contentsOfURL: url)
imageView.image = UIImage(data: data!)// <--- ERROR HERE: EXC_BAD_INSTRUCTION
}
//Print Log
//print(card.logDescription)
}
}
Like the comment says above, I get the error on the imageView.image = UIImage(data: data!) line:
Thread 1: EXC_BAD_INSTRUCTION
Here is the code for cardImageURL:
var cardImageURL: String {
return String(format: "http://testyard.example.net/display/images/cards/main/%#", image)
}
//This is a computed variable when a "Card" class object is created.
It returns the correct url in a string:
http://testyard.example.net/display/images/cards/main/armor-of-testing.jpg
I've used this code elsewhere, and it worked fine, why is it throwing errors here?
Thanks in advance.
Are you sure the data being downloaded is an image? You should probably use this line:
if let image = UIImage(data: data)`
This should stop the error, though you might need to test that your data actually contains an image.
Related
I'm struggling to download pictures from firebase storage to an UIImage in swift 5.
I can well upload them. When I tried to retrieve picture, the UIImage display a black screen.
here my function which return the UIImage
import UIKit
import Firebase
func getImageEvent (imagePath : String) -> UIImage? {
var myImage : UIImageView?
//Access to the storage
let storageRef = Storage.storage().reference(withPath: imagePath)
storageRef.getData(maxSize: 1 * 1024 * 1024) {(data, error) in
if let error = error {
print(error.localizedDescription)
return
}
if let data = data {
print(data.description)
myImage?.image = UIImage(data: data)
}
}
return myImage?.image
}
//Call the function
getImageEvent (imagePath :"9U4BoXgBgTTgbbJCz0zy/eventMainImage.jpg")
In the console, I can well see a value for print(data.description).
By default, there is an image in the UIImageView. When call the function, the default image is replaced by a black screen.
Could you please help me to understand the mistake ?
many thanks
There's a number of ways to go about this but a brief description of the issue first:
The return statement within the closure will execute way before that image is downloaded - Firebase functions are asynchronous and code has to be crafted in a way that allows for time to download and get data from the internet. So - don't try to return data from asynchronous functions.
Here's the code re-written with a completion handler. That handler will be called only after the image is fully downloaded.
func getImageEvent (imagePath: String, completion: #escaping(UIImage) -> Void) {
var myImage : UIImageView?
let storageRef = Storage.storage().reference(withPath: imagePath)
storageRef.getData(maxSize: 1 * 1024 * 1024) { data, error in
if let error = error {
print(error.localizedDescription)
return
}
if let data = data {
if let myImage = UIImage(data: data) {
completion(myImage)
}
}
}
}
and the key is how to call that function. Note this code awaits the data (UIImage) to be passed back to it within it's closure and lets you know that getting the image was complete.
self.getImageEvent(imagePath: "9U4BoXgBgTTgbbJCz0zy/eventMainImage.jpg", completion: { theImage in
print("got the image!")
})
You should add additional error checking in case the image was not downloaded or myImage was nil. Passing back an error message along with the nil myImage would be one option, or making the object passed back as an optional and then checking for nil within self.downloadImageAtPath would be another.
To complete the solution, below the code used to in tableView to get picture in a particular cell
getImageEvent(imagePath: myArray[indexPath.row].partyImagePath) { (image) in
cell.partyImage.image = image
}
I am parsing a JSON within my viewDidLoad method. One of the keys within this JSON is the image URL, which goes into a a string array called "allCImages"
This is just a string. Therefore to populate the image into the cell, in my cellForRowAt method, I have the following:
cell.vcCellImage.downloadImage(from: allCImages[indexPath.section])
Note: vcCellImage is the IBOutlet of my cell image view.
The "downloadImage" method is part of the following extension:
extension UIImageView {
func downloadImage(from imgURL: String!) {
let theUrl = URLRequest(url: URL(string: imgURL)!)
// set initial image to nil so it doesn't use the image from a reused cell
image = nil
// check if the image is already in the cache
if let imageToCache = vc1ImageCache.object(forKey: imgURL! as NSString) {
self.image = imageToCache
print("Image is in Cache")
return
}
// download the image asynchronously
let task = URLSession.shared.dataTask(with: theUrl) { (data, response, error) in
if error != nil {
print(error!)
return
}
DispatchQueue.main.async {
// create UIImage
let imageToCache = UIImage(data: data!)
// add image to cache
vc1ImageCache.setObject(imageToCache!, forKey: imgURL! as NSString)
self.image = imageToCache
}
}
task.resume()
}
This is working almost perfectly. For example:
1) If I scroll down my tableview slowly, all the cells contain the correct image
2) If I scroll up my tableview, slowly or quickly, all the cells contain the correct image. This is proven by the fact that my console is printing the following:
Image is in Cache
Image is in Cache
Image is in Cache
I.e, the tableview is getting my image from the cache (since to scroll up, I must have scrolled down before)
3) The issue is if I scroll down my tableview really quickly, on the first attempt. Since the image has not cached yet, the cell will display the wrong image, before changing to the correct image. Classic problem
Therefore I am missing this small piece of logic. How to resolve this?
EDIT: I tried this but the issue remains:
class VCTableViewCell: UITableViewCell {
override func prepareForReuse() {
super.prepareForReuse()
vcCellImage.image = nil
}
This occurs because of
1- cell dequeueing : cells are re-used inside the tableView
2- when you scroll before a request happens it may cause a new 1 with same url
Best option is using SDWebImage
I have faced the similar issue.
I have fixed this issue by cancelling the image request in the prepareForReuse method.
Can you try the same?
first off all if you are appending your api or any data like this just remove this
var arr = [string]()
viewDidLoad()
{
arr.append("s","sd","sd)
}
accept this
var arr = [string]()
viewWillAppear()
{
arr.removeAll()
//call api
//append Data
arr.append("s","sd","sd)
}
I have similar problem then I solve it like this, may be it helpful for you also.
I have a tableView which display a list of traffic-cameras parsed from a XML file. When I select a cell, it sends the ImageURL, Roadname, Coordinates etc. via the prepareForSegue method.
In my detailviewcontroller I declare the incoming values as the following:
var selectedFeedURL = String()
var selectedFeedRoadname = String()
var selectedFeedLongitude = String()
var selectedFeedLatitude = String()
I have no problem printing all the values into the log or set it as labels. The problem occurs when I try to load the selectedFeedURL (which is the URL to the image, i.e: http://webkamera.vegvesen.no/kamera?id=559847) and set it to my imageView..
In my viewDidLoad, I have the following code, which should download the image and set it to my imageView named cameraImageView.
if let url = NSURL(string:"\(selectedFeedURL)") {
if let data = NSData(contentsOfURL: url){
print("Suksess")
cameraImageView.image = UIImage(data: data)
}
}
My imageView stays empty and I doesn't get any errors or complains in the debug area. If I print out the selectedFeedURL, the link is there.
The weird part is that if I change
NSURL(string:"\(selectedFeedURL)")
to
NSURL(string:"http://webkamera.vegvesen.no/kamera?id=559847")
Basically changing the variable to a camera URL, it works perfectly.
Soo... any suggestions on what the problem might be?
Much appreciated :)
If there are white spaces and newline characters at the start and end of your URL string, it won't work.
Try:
selectedFeedURL = selectedFeedURL.stringByTrimmingCharactersInSet(.whitespaceAndNewlineCharacterSet())
if let url = NSURL(string: selectedFeedURL) {
if let data = NSData(contentsOfURL: url){
print("Suksess")
cameraImageView.image = UIImage(data: data)
}
}
I have a button to save picture data in core data but when I push it, it is freezing because size of the data is big. I did try to use dispatch_async but it didn’t work. How do I create the icon/indicator showing that it is loading/bookmarking rather than just freezing?
#IBAction func save() {
let content = self.foodMenu?["content"].string
let urlString = self.foodMenu?["thumbnail_images"]["full"]["url"]
let urlshare = NSURL(string: urlString!.stringValue)
let imageData = NSData(contentsOfURL: urlshare!)
let images = UIImage(data: imageData!)
dispatch_async(dispatch_get_main_queue(), {
if let managedObjectContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext {
self.foodClass = NSEntityDescription.insertNewObjectForEntityForName("Foods",
inManagedObjectContext: managedObjectContext) as! Foods
self.foodClass.content = content
self.foodClass.image = UIImageJPEGRepresentation(images, 1)
var e: NSError?
if managedObjectContext.save(&e) != true {
println("insert error: \(e!.localizedDescription)")
return
}
}
First, it is unlikely it is the save that is slow. I would suspect that your creation of the JPEG representation is the slow part.
Second, you are wanting to hide a problem by putting up a spinner. That really is bad for the user experience. Far better to do the following (yes it is more code);
Move your image creation and saving to a background queue.
Restructure your Core Data stack so that your saves to disk are on a private queue.
This involves using a background queue and multiple contexts in Core Data but getting this data processing off the User Interface thread is the right answer.
I was hoping I could have some advice. I'm making a quiz app, which contains images. The quiz has 4 answer boxes with a single image view. I can download the images into the quiz via parse.com, however I now want to be able to click on the image which then goes to a separate view controller so you can zoom into the image in full screen. I have been able to call the pffile and segue it, however my app crashes when I try and getdatainbackgroundwithblock in the second view controller.
How do you think I should segue the image?
EDIT
Yes sorry. So the crash I was getting was an error at code=1 address=0x48, which occurred at line +55 of getdatainbackgroundwithblock.
I have pasted snipped of the code I was using below.
I used this to call the image in the first view and make it into an image in my PFImageView.
`for object : PFObject in objectsArray as! [PFObject] {
let image = object["Image"] as! PFFile
let transimage = image
image.getDataInBackgroundWithBlock {
(imageData:NSData?, error:NSError?) -> Void in
if error == nil {
let finalimage = UIImage(data: imageData!)
// self.imageView.append(finalimage!)
self.imageView.image = final image`
I then passed it to my second view controller like this.
`override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "ZoomImage"){
// Get the new view controller using [segue destinationViewController].
var detailScene = segue.destinationViewController as! ZoomImageViewController
detailScene.currentObject = transimage as! PFFile
NSLog("checkone")
}
}`
In my second view controller I tried to make it back into an image like this.
` if let object = currentObject {
NSLog("(currentObject)")
var initialThumbnail = UIImage(named: "question")
NSLog("check1")
imageView.image = initialThumbnail
NSLog("check2")
NSLog("check3")
object.getDataInBackgroundWithBlock {
(imageData:NSData?, error:NSError?) -> Void in
if error == nil {
NSLog("check4")
let finalimage = UIImage(data: imageData!)
// self.imageView.append(finalimage!)
self.imageView.image = finalimage
NSLog("check5")`
I would get an NSLog of 3, and then the code would break. The NSLog for the currentObject also brought back a PFFile, so I believed it to be true. Where am I going wrong? And is there a better way to pass it?
You were right, I didn't need getdata. I got rid of that and instead of seguing my pffile I segued the pfobject carrying the image and the text. I then called the object as a file and put it in the uiimageview. I'll post the code I used in a bit incase anyone wants it.
Why you call getDataInBackgroundWithBlock in both view controllers ?
You already fetch the data in your PFFile instance so no need to call it twice. It's could be the issue.