i'm getting fatal error: unexpectedly found nil while unwrapping an Optional value
imagedata is not nil it has a value of 2604750 bytes
I don't know why it show this error as I can see img1 is nil why ?
any comments !!!
#IBOutlet var img1: UIImageView!
#IBOutlet var img2: UIImageView!
// in viewWillAppear I gave it a default image
self.img1.image = UIImage(named: "dummy.png" )
self.img1.image = UIImage(named: "dummy.png" )
// i changed to send the nsmanagedobject but it's still same error
func setimage(person: NSManagedObject){
let data: NSData = NSData()
if person.valueForKey("picture") as! NSData == data{
if person.valueForKey("tag") as! Int == 1 {
img1.image = UIImage(named: "dummy" )
}else if person.valueForKey("tag") as! Int == 2 {
img2.image = UIImage(named: "dummy")
}}
else{
if person.valueForKey("tag") as! Int == 1 {
img1!.image = UIImage(data: person.valueForKey("picture") as! NSData )
}else if person.valueForKey("tag") as! Int == 2 {
img2.image = UIImage(data: person.valueForKey("picture") as! NSData )
}
}
}
So, you have a simple mistake. In fact your outlets were nil. However, not because you did not assign them in the storyboard, but because the setimage was called on a different instance of ViewController.
You have a property view1 in your second view controller which is declared as:
let view1: ViewController = ViewController()
This creates a NEW instance of ViewController. When you then call view1.setimage you get a crash because outlets for THIS instance are not connected.
The property in your second view controller should be
var view1: ViewController!
and in your imageTapped method of the ViewController you should modify code so it has this line:
view.view1 = self
Forced unwrapping might not be ideal, but it should work as long as you ensure that whenever you instantiate your second view controller you set the view1 property.
I think is the same thing as Andriy is suggesting. Probably your Outlet for the image is not connected with the view.
Your outlets are nil, there are a couple of reasons why this could happen.
They have not been connected in the interface builder.
You are accessing them before they have been instantiated, e.g. before viewDidLoad() has been called.
Related
I have a scrollView that contains a dynamic amount of WeatherViewControllers each displaying the weather data of a different city the user has saved. The user can segue from the WeatherViewControllers to a CityListViewController. Where they can add and remove cities from their list which in turn should add and remove WeatherViewControllers from the scrollView upon dismissing the CityListViewController, this is where I am running into a problem.
Currently I am trying to use a protocol in to call the func reloadScrollView which calls viewDidLoad in the scrollViewController upon dismissing(viewDidDisappear) the CityListViewController but am getting an error:
Fatal error: Unexpectedly found nil while unwrapping an Optional value: file
when it gets to:
totalScrollView.addSubview(weatherScreen.view)
Using debugger I have found that totalScrollView is nil and that is causing the problem. Is there a way to make the scrollView load so it is not nil when dismissing the other viewController
OR
is the a better time to call use this protocol to call this function?
Side Note: Upon initially opening the app the scrollView loads properly with all the correct WeatherViewControllers in the UIScrollView and the correct cities in the list.
class ScrollViewController: UIViewController, ScrollReloadProtocol {
func reloadScrollView() {
print("SCROLL RELOADED!!!!!*******")
self.viewDidLoad()
}
#IBOutlet var totalScrollView: UIScrollView!
var pages = [ViewController]()
var x = 0
var weatherScreensArray = [SavedCityEntity]()
var weatherScreenStringArray = [String]()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
var horizString = "H:|[page1(==view)]"
let defaults = UserDefaults.standard
override func viewDidLoad() {
super.viewDidLoad()
//userDefaults used to keep track of which screen is which to put different cities on different viewControllers
defaults.set(0, forKey: "screenNumber")
//load cities to get number of cities saved
loadCities()
var views : [String: UIView] = ["view": view]
//create all weatherWeatherControllers
while x <= weatherScreensArray.count {
pages.append(createAndAddWeatherScreen(number: x))
weatherScreenStringArray.append("page\(x+1)")
views["\(weatherScreenStringArray[x])"] = pages[x].view
let addToHoriz = "[\(weatherScreenStringArray[x])(==view)]"
horizString.append(addToHoriz)
x+=1
}
horizString.append("|")
let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:|[page1(==view)]|", options: [], metrics: nil, views: views)
let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: horizString, options: [.alignAllTop, .alignAllBottom], metrics: nil, views: views)
NSLayoutConstraint.activate(verticalConstraints + horizontalConstraints)
}
//Function to create and add weatherViewController
func createAndAddWeatherScreen(number: Int) -> ViewController {
defaults.set(number, forKey: "screenNumber")
let story = UIStoryboard(name: "Main", bundle: nil)
let weatherScreen = story.instantiateViewController(identifier: "View Controller") as! ViewController
weatherScreen.view.translatesAutoresizingMaskIntoConstraints = false
totalScrollView.addSubview(weatherScreen.view)
addChild(weatherScreen)
weatherScreen.didMove(toParent: self)
return weatherScreen
}
}
Skipping that fact that your are not doing it right, let's forcus on the one issue at a time. You are trying to access the totalScrollView implicitly in the viewDidLoad where if the outlet is linked it should be loaded at that point. If it is nil you should:
Make sure that you have the .storyboard or .xib file defining the ScrollViewController layout.
Make sure you are loading this controller from that storyboard/xib.
Make sure that the view controller in the storyboard/xib file has set its class to ScrollViewController, similar to the following print screen:
Make sure that the outlet is linked in the storyboard/xib to this property in your code file (probably ScrollViewController.swift). If not:
open storyboard and sorucecode file in separate editors
drag and drop from the dot on the left of the property declaration to the UIScrollView in the storyboard
make sure that there is added a link to Referencing Outlets
I'm trying to populate a label in my custom cell for my UITableViewController with information from my Firebase Database but I keep running into this error:
"Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value"
I did read this link: What does "fatal error: unexpectedly found nil while unwrapping an Optional value" mean?
I don't think I'm accessing outlets before they're loaded in and I did check that my IBOutlet connection is correct.
class FeedCell: UITableViewCell {
#IBOutlet weak var postText: UILabel!
}
class FeedTableViewController: UITableViewController {
var postInfo = FeedCell()
override func viewDidLoad() {
super.viewDidLoad()
// Uncomment the following line to preserve selection between presentations
// self.clearsSelectionOnViewWillAppear = false
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem
self.tableView.rowHeight = 100.0
// postText = UILabel()
//
var ref: DatabaseReference!
ref = Database.database().reference()
let cellRef = ref.child("post/body")
cellRef.observeSingleEvent(of: .value) { (snapshot) in
if let body = snapshot.value as? String {
self.postInfo.postText.text = body
print(body)
}
}
}
I expected the label to be updated with the body text "test firebase" but I'm just running into that error. Is it because I defined my IBOutlet in another class then referenced it in my FeedTableVIewController? Any advice would be appreciated!
The problem is here
var postInfo = FeedCell()
with
self.postInfo.postText.text = body <<< postText is nil
First you shouldn't create an instance var of a cell , and as your current var here postInfo is initated with FeedCell() so the outlet is nil regardless of it's connected / not
Second you should make use of table delegate and dataSource methods to populate your table
I have an image URL that needs to be parsed and displayed. The URL exists, but returns nil.
It successfully parses in the cellForRowAt function by calling cell.recipeImage.downloadImage(from: (self.tableViewDataSource[indexPath.item].image))
With this line the image displays. However, it doesn't exist when calling it in didSelectRowAt
RecipeTableViewController.swift
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let Storyboard = UIStoryboard(name: "Main", bundle: nil)
let resultsVC = Storyboard.instantiateViewController(withIdentifier: "ResultsViewController") as! ResultsViewController
// Information to be passed to ResultsViewController
if (tableViewDataSource[indexPath.item] as? Recipe) != nil {
if isSearching {
resultsVC.getTitle = filteredData[indexPath.row].title
//resultsVC.imageDisplay.downloadImage(from: (self.filteredData[indexPath.row].image))
} else {
resultsVC.getTitle = tableViewDataSource[indexPath.row].title
// Parse images
resultsVC.imageDisplay.downloadImage(from: (self.tableViewDataSource[indexPath.row].image))
}
}
// Push to next view
self.navigationController?.pushViewController(resultsVC, animated: true)
}
extension UIImageView {
func downloadImage(from url: String) {
let urlRequest = URLRequest(url: URL(string: url)!)
let task = URLSession.shared.dataTask(with: urlRequest) { (data,response,error) in
if error != nil {
print(error!)
return
}
DispatchQueue.main.sync {
self.image = UIImage(data: data!)
}
}
task.resume()
}
}
ResultsViewController.swift
class ResultsViewController: UIViewController {
var getTitle = String()
var getImage = String()
#IBOutlet weak var recipeDisplay: UILabel!
#IBOutlet weak var imageDisplay: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
recipeDisplay.text! = getTitle
}
...
}
Returns the error
Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value
From my understanding, the app is getting crashed at this line:
recipeDisplay.text! = getTitle
If it is, obviously this is not the proper way to do it. Just remove the force unwrapping because the text on the label here is nil by default. Force referencing a nil value will crash the app.
recipeDisplay.text = getTitle
UPDATED:
- Let's make sure that you wired the label and the outlets properly. Connect ti to the VC, not the File Owner.
You're calling view-related code on views that haven't been initialized yet. Remember, IBOutlets are implicitly unwrapped properties, so if you try to access them before they're initialized they'll force-unwrap and crash. So it's not that the UIImage is coming up nil, it's that recipeDisplay is nil and is getting force unwrapped.
The idiomatic iOS thing to do is to hand a view model of some sort (an object or a struct) to the view controller, and then let it do the work with that item once it has finished loading.
So, in you didSelect method, you could create your view model (which you'd need to define) and hand it off like this:
let title = filteredData[indexPath.row].title
let imageURL = self.tableViewDataSource[indexPath.row].image
let viewModel = ViewModel(title: title, imageURL: imageURL)
resultsVC.viewModel = viewModel
And then in your resultsVC, you'd do something like this:
override func viewDidLoad() {
super.viewDidLoad()
if let vm = viewModel {
recipeDisplay.text = vm.title
downloadImage(from: vm.imageURL)
}
}
So in your case all you'd need to do is hand those strings to your VC (you can wrap them up in a view model or hand them off individually) and then in that VC's viewDidLoad() that's where you'd call downloadImage(from:). That way there's no danger of calling a subview before that subview has been loaded.
One last note: Your download method should be a little safer with its use of the data and error variables, and its references to self. Remember, avoid using ! whenever you don't absolutely have to use it (use optional chaining instead), and unless you have a really good reason to do otherwise, always use [weak self] in closures.
I'd recommend doing it like this:
func downloadImage(from url: String) {
let urlRequest = URLRequest(url: URL(string: url)!)
let task = URLSession.shared.dataTask(with: urlRequest) { [weak self] (data,response,error) in
if let error = error {
print(error)
return
}
if let data = data {
DispatchQueue.main.sync {
self?.image = UIImage(data: data)
}
}
}
task.resume()
}
Update: Because the 'view model' concept was a little too much at once, let me explain.
A view model is just an object or struct that represents the presentation data a screen needs to be in a displayable state. It's not the name of a type defined by Apple and isn't defined anywhere in the iOS SDK. It's something you'd need to define yourself. So, in this case, I'd recommend defining it in the same fine where you're going to use it, namely in the same file as ResultsViewController.
You'd do something like this:
struct ResultsViewModel {
let title: String
let imageURL: String
}
and then on the ResultsViewController, you'd create a property like:
var viewModel: ResultsViewModel?
or if you don't like dealing with optionals, you can do:
var viewModel = ResultsViewModel(title: "", imageURL: "")
OR, you can do what you're already doing, but I'd highly recommend renaming those properties. getTitle sounds like it's doing something more besides just holding onto a value. title would be a better name. Same criticism goes for getImage, with the additional criticism that it's also misleading because it sounds like it's storing an image, but it's not. It's storing an image url. imageURL is a better name.
I am new to swift and I am trying to make this note app. I have split view controller that goes in my first view controller and that view controller connects to a table view controller. Everything works perfectly is just that when I launch the app I have all the notes like I want but when I try to go back to my first view controller and come back to my table view controller, all the notes are duplicated every single time I do it. I tried everything I can try, is there anyone who can help me
my MasterViewController is
import UIKit
class MasterViewController: UITableViewController {
var detailViewController: DetailViewController? = nil
override func viewDidLoad()
{
super.viewDidLoad()
Note.loadNotes() // The problem is here, I think
noteTable = self.tableView
// Do any additional setup after loading the view, typically from a nib.
let addButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(insertNewObject(_:)))
navigationItem.rightBarButtonItem = addButton
if let split = splitViewController
{
let controllers = split.viewControllers
detailViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? DetailViewController
}
}
My loadNotes function is
class func loadNotes()
{
let defaults:UserDefaults = UserDefaults.standard
let saveData: [NSDictionary]? = defaults.object(forKey: kAllNotes) as? [NSDictionary]
if let data:[NSDictionary] = saveData
{
for i:Int in 0 ..< data.count
{
let n:Note = Note()
n.setValuesForKeys(data[i] as! [String : Any])
allNotes.append(n)
}
}
}
Your loadNotes method keeps appending. The first line of loadNotes should be:
allNotes = [Note]()
Then it starts with an empty array and fills it up.
And why is loadNotes a static method? That's a bad design. Make Notes a normal class and make loadNotes an instance method.
On an unrelated note (no pun intended), do not use UserDefaults to store app data. Only use it to store little bits of information.
I have a default image in viewItem to make sure that it is working, it shows on the detail view of the splitview.
#IBOutlet weak var ImageView: UIImageView!
var imageCache = [String: UIImage]()
override func viewDidLoad() {
super.viewDidLoad()
self.configureView()
}
func configureView() {
if let detail: AnyObject = self.detailItem {
if let label = self.detailDescriptionLabel {
let dict = detail as [String: String]
label.text = ""
let s = dict["result"]
let vr = NString(string: s!)
let vrd = vr.doubleValue
let value = ceil(vrd*20)
let valueString = String(format: "%.0f", value)
vresult.text = "\(valueString)%"
getPic(dict) // <---- trouble maker
fitem.hidden = false
ritem.hidden = false
}
} else {
navigationController?.popViewControllerAnimated(true)
}
}
func getPic(item: [String: String]) {
var chachedImage = self.imageCache[item["image"]!]
println(item["image"]) // <-- prints out the url
if cachedImage == nil {
var imgUrl = NSURL(string: item["image"]!)
let request: NSURLRequest = NSURLRequest(URL: imgUrl!)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue(), completionHandler: {( reponse: NSURLResponse!, data: NSData!, error; NSError!) -> Void in
if error == nil {
cachedImage = UIImage(data: data)
println("got here no problem") // <-- prints out
self.imageCache[item["image"]!] = cachedImage
println(self.imageCache) // <-- prints reference OK
dispatch_async(dispatch_get_main_queue(), {
self.ImageView.image = cachedImage // <---- offender
})
} else {
println("Error: \(error.localizedDescription)")
}
})
} else {
dispatch_async(dispatch_get_main_queue(), {
self.ImageView.image = cachedImage
})
}
}
ImageView is coming up nil every time.
fatal error: unexpectedly found nil while unwrapping an Optional value
but the default image shows. I've moved this out of the dispatch and even tried setting it straight from the viewDidLoad() always errors. It used to be a UIWebView and worked perfectly except that it would not cache anything. Since loading these images is a lot of work, I thought caching would be good, I've got caching working for thumbnails in the MASTER view.
It may be because of how your instaciating your viewcontroller.
let vc = MyViewController()
Something like this wont work. You're creating the VC without actually giving the storyboard a chance to link the IBOutlets. Instead use
storyboard.instantiateViewControllerWithIdentifier(identifier: String)
You may need to get reference to the storyboard using
let storyboard = UIStoryboard(name: name, bundle: NSBundle.mainBundle())
Hope this helps :)
Changing your variable name shouldn't make any difference except for readibility/maintainability unless there's a namespace conflict (good to understand why/where that might be happening). Also I was wondering - you made the IBOutlet'ed varable weak. When the last remaining strong ref to the object goes away, the weak references to the object are set nil by the runtime/garbage collector automatically. (Look up that section of the Swift documentation if you're not solid about it).
Maybe you should check your classes and controllers by adding deinit { println(,"function name deallocated' }. Between your use of weak and improved behavior seen when you change the variable name, it seems like there might be some weird (buggy) interactions going on in your app itself.
Well silly me. I've been working on this for a few days, I got the great idea to try and change the name, and it worked. I tried changing it back and it broke, apparently you can't use ImageView as a variable!
In my case was because I was using a nib and didn't register it.
Once I did registered it, it worked
My case Was Different I used
awakeFromNib()
instead of
viewDidLoad()
.