Upon a button press, I need to pull down paginated data (pulling down pins from Pinterest IOS SDK, the pins are limited to 25 per call), i.e. I need my code to iterate until responseObject no longer .hasnext. What's the best way to approach this? I can press the button over and over to pull it all down, but I want to automate it so there's only 1 button press required.
#IBAction func didPressGetPinsButton(sender: UIButton) {
if self.fetchingMore == false && self.currentResponseObject.hasNext() {
self.fetchingMore = true
self.currentResponseObject.loadNextWithSuccess({ (nextResponseObject :PDKResponseObject!) -> Void in
self.fetchingMore = false
self.currentResponseObject = nextResponseObject
guard let unwrappedArrayOfPins = nextResponseObject.pins() as? [PDKPin] else {return}
for pin in unwrappedArrayOfPins {
pins.append(pin)
}
put the action code into a separate function, so that you call it for the first time from the button press, and then you keep re-calling it while .hasNext
#IBAction func didPressGetPinsButton(sender: UIButton) {
actionGetPins()
}
func actionGetPins() {
// all your code
if nextResponseObject.hasNext() {
actionGetPins()
}
}
Depending on how long it takes to get all of the data, you might also want to run the whole function in a background task, but you should at least add a busy indicator to show that there's still work being done.
Related
So I have this code:
#IBAction func onStart(_ sender: Any) {
DispatchQueue(label: "SyncQueue").async{
for i in 0..<numberOfItemToDownload {
// download data from the internet this may takes longer depends on the connection speed and data being download
if isCancelled {
DispatchQueue.main.async { // dismiss the progress ViewController (displayed modally) }
break
}
}
}
}
#IBAction func onEnd(_ sender: Any) {
isCancelled = true
}
This works ok, but if the current item being download takes longer then the user taps the "End" button the "progress dialog" is not dismissed until the current item is done. This makes the "End" button not working in user's perspective.
In Android we can interrupt the AsyncTask process and end it. Is there another way to do it in Swift? like when the user taps the "End" the process should immediately stop and dismiss the "progress dialog".
GDC is not easily cancellable.
Use an NSOperation subclass then you can cancel easily and quickly.
I have static data (3 values) coming from CloudKit, and the problem is when I refresh the UITableView, I get 6 values instead of 3 values.
I'm not sure why it doesn't refresh and throw out old data from the Array, but instead it keeps the old data and adds the same data to it Array.
Initial UITableView set up:
func getData() {
cloud.getCloudKit { (game: [Game]) in
var teamColorArray = [String]()
for item in game {
let itemColor = item.teamColor
teamColorArray.append(itemColor)
print("TCA in: \(teamColorArray)")
}
self.teamColorArray = teamColorArray
self.tableView.reloadData()
}
}
Prints: ["CC0033", "FDB927", "E3263A"]
Refresh data when UIRefreshControl pulled:
#IBAction func refreshData(_ sender: Any) {
self.teamColorArray.removeAll()
getData()
self.refreshControl?.endRefreshing()
}
Prints: ["CC0033", "FDB927", "E3263A", "CC0033", "FDB927", "E3263A"]
I think I have it narrowed down to somehow game in the function getData() is incremented to a count of 6 items. I'm not sure why it wouldn't always stay at 3 items if it were pulling all new data from CloudKit, but maybe I'm not understanding that calling a completion handler doubles the values and maybe I need to removeAll inside of that? I'm just really not sure
Does anyone have anything they see I'm doing wrong, or anything they'd do to fix my code?
Thanks!
Might have to do with your async call to cloudkit. I'm not too familiar with refresh control but here is a way to maybe solve your problem and also make your code a little cleaner.
func getData(_ completion: () -> ()) {
teamColorArray.removeAll()
cloud.getCloudKit { [weak self] (game: [Game]) in
guard let unwrappedSelf = self else { return }
var updatedColorArray = [String]()
game.forEach { updatedColorArray.append($0.teamColor) }
unwrappedSelf.teamColorArray = updatedColorArray
completion()
}
}
now when you call getData it would look like this
getData {
DispatchQueue.main.async { [weak self] in
self?.tableView.reloadData()
self?.refreshControl?.endRefreshing()
}
}
you add weak self to remove the possibility of retain cycles
make sure your updating UI from the main thread
Call reloadData and endRefreshing when you know the array has been set properly
I put teamColorArray.removeAll() inside the getData function since it seems like you will need to call it everytime and it saves you from having to add it before the function everytime.
I have a Button on First VC which is directed to two active states.
1) SecondVC
override func viewDidLoad() {
super.viewDidLoad()
subjectPickerView.dataSource = self
subjectPickerView.delegate = self
SwiftyRequest()
// Used the text from the First View Controller to set the label
}
func SwiftyRequest(){
print("SecondViewController METHOD BEGINS")
let jsonobj = UserDefaults.standard.object(forKey: "PostData")
let json = JSON(jsonobj as Any)
for i in 0 ..< json.count{
let arrayValue = json[i]["name"].stringValue
print(arrayValue)
self.subjects.append(arrayValue)
self.subjectPickerView.reloadAllComponents()
}
print(self.subjects)
}
2) IBAction of FirstVC
#IBAction func buttonPressed(_ sender: Any) {
Alamofire.request("http://localhost/AIT/attempt3.php",method: .post, parameters: ["something": semValue, "branch" : streamValue])
.responseJSON { response in
print(response.result)
if let JSON1 = response.result.value {
print("Did receive JSON data: \(JSON1)")
// JSONData.someData = JSON1 as AnyObject?
UserDefaults.standard.set(JSON1, forKey: "PostData")
UserDefaults.standard.synchronize()
}
else {
print("JSON data is nil.")
}
}
}
NOW, Whenever i pressed the button it calls the viewDidLoad of SecondVC before IBAction of FirstVC which is a bit problematic for my app! How can i decide the priority between these two function.
You have to think about what you want to happen. Clearly the Alamofire call is going to take some time. What do you want to do with the 2nd VC while that time elapses? What do you want to do if the call does not return at all?
This is a common problem when dependent on external resources. How do you manage the UI? Do you present the UI in a partial state? Do you put a popover saying something like "loading". Or do you wait for the resource to complete before presenting the 2nd VC at all?
We cannot make that decision for you, since it depends on your requirement. There are ways to implement each one, though. If the resource usually responds quickly you could show the VC in a partial state and then populate it on some kind of callback. Typically call backs are either (1) blocks (2) delegate methods or (3) notifications. There is also (less commonly) (4) KVO. You should probably research the pros and cons of each.
I'm trying to perform a segue to a new view controller, but the segue is being called twice and the new view controller appears twice.I'm using a method that performs a GET request to an API to retrieve data.That method uses a completion handler.
func getSearchResultsForQuery(_ query: String, completionHandlerForSearchResultsForQuery: #escaping (_ success: Bool, _ error: NSError?) -> Void)
When the method completes successfully my segue is called, from within the main queue as is required.
I've set breakpoints so I could see what was going on and the execution jumps from the performSegue back up to the conditional that checks if the method was successful and then continues until the segue is called a second time. I've tried a purely programatic segue, but the result was the same.I also added a print statement, and if I comment out the segue the print statement is only called once.
I've used this same pattern a number of times before and never had a problem with it and I just can't figure out why this is happening.The only thing I'm doing different this time is using Swift 3 and using DispatchQueue.main.async instead of dispatch_async(dispatch_get_main_queue(). Here is the function which is giving me this problem:
#IBAction func search(_ sender: UIButton) {
let searchQuery = searchField.text
TIClient.sharedInstance().getSearchResultsForQuery(searchQuery!) { (success, error) in
if success {
print("Food items fetch successful")
DispatchQueue.main.async {
print("Perorming segue for food item: \(searchQuery)")
self.performSegue(withIdentifier: "showFoodItems", sender: self)
}
} else {
print("error: \(error)")
}
}
}
Edit: I never found out what the problem was, but completely deleting the story board and recreating it solved it.
I know this isn't a great way to fix this issue, Also I can't leave a comment due to low reputation but what happens if you wrap the whole if statement in DispatchQueue.main?
#IBAction func search(_ sender: UIButton) {
let searchQuery = searchField.text
TIClient.sharedInstance().getSearchResultsForQuery(searchQuery!) { (success, error) in
DispatchQueue.main.async {
if success {
print("Food items fetch successful")
self.performSegue(withIdentifier: "showFoodItems", sender: self)
} else {
print("error")
}
}
}
Would that yield a different result or still the same result? checking for Bool doesn't require too much processing power so I don't think putting it in a main queue is a bad thing but I'd do this to trouble shoot. Sorry I can't just comment on this.
Check in storyboard, maybe you set segue from your button action instead of controller.
I'm new to programming with iOS and Swift. I have a label that should automatically be updated when the status of the StreamingKit Framework changes.
Currently the label only changes when I press a different button (it calls the self.updateView() function again), but I want it to happen automatically when the status has changed, not by pressing a different button.
Here is the code:
func updateView() {
dispatch_async(dispatch_get_main_queue()) {
if let label = self.bufferingLabel, let button = self.playerButton{
if let audioPlayer = self.player{
if(audioPlayer.state == STKAudioPlayerStateBuffering)
{
self.playerState = "Loading"
button.setImage(self.image1, forState: UIControlState.Normal)
}
else(audioPlayer.state == STKAudioPlayerStatePlaying)
{
self.playerState = self.defaultPlayerState
self.playerState = "Playing"
button.setImage(self.image1, forState: UIControlState.Normal)
}
label.text = self.playerState!
}
}
So when I press this button, it gives the first state (which is loading), but after that is done (status changed), the label should change to play, but it doesn't.
#IBAction func pressStart(sender: AnyObject) {
//declare path to streaming
let filePath = "http://mp3.streampower.be/mnm-high.mp3"
if player == nil {
self.player = STKAudioPlayer()
self.player?.delegate = self
}
if let audioPlayer = player{
if (audioPlayer.state == STKAudioPlayerStateReady) ||
(audioPlayer.state == STKAudioPlayerStateStopped){
audioPlayer.play(filePath)
}else{
audioPlayer.stop()
}
}
self.updateView()
}
Some of the delegates I tried as well
func audioPlayer(audioPlayer: STKAudioPlayer!, didStartPlayingQueueItemId queueItemId: NSObject!) {
self.updateView()
}
func audioPlayer(audioPlayer: STKAudioPlayer!, didFinishBufferingSourceWithQueueItemId queueItemId: NSObject!) {
self.updateView()
}
func audioPlayer(audioPlayer: STKAudioPlayer!, stateChanged state: STKAudioPlayerState, previousState: STKAudioPlayerState) {
self.updateView()
}
You should look and use the delegate property of the STKAudioPlayer.
I'm not familiar with it, but generally in the iOS world, that's how you receive events from an object (the object delegates some stuff to the object of your choice).
You can use NSNotifications to send a signal whenever the streaming kit changes. Then you can add an observer to your UI view controller that will trigger a function whenever it receives a signal.
If you want to try out functional reactive programming you can also use The Reactive Cocoa framework to do a similar signal observer pattern. And finally, there is plain old key-value observation. One of these options should be able to help you.