I am newbie in swift and I am building an app that similar to vine. First I open my app I am following the codes as you seen in the below
videoArray.removeAll()
let url = NSURL(string: "http://....")!
self.videoArray.removeAll()
Mellon.getExploreVideos(url,cache: cache, completionHandler: { (data, response, error) -> () in
dispatch_async(dispatch_get_main_queue()){
self.videoArray = data!
self.tableView.reloadData()
}
})
override func viewDidDisappear(animated: Bool) {
cache?.removeAllObjects()
videoArray.removeAll()
tableView.reloadData()
NSNotificationCenter.defaultCenter().removeObserver(self.tableView)
print("siliniyor")
}
In every 8 cell I am calling that getExplore func. I have about 80 videos in my tableview cell in my custom view cell I am building an AVURLAsset and AVplayer. I also set objects for cache in getExplore and when I close view controller I am removing all of them but as you seen from the picture all memory is not removing in every time I scroll tableview begin to end(I have 80 videos that tableView) and I change to view controller and back again I have 20 mb surplus in memory and at the end my app crush. What should I do for this problem? If the informations are not enough I can edit.
In your viewDidDisappear, make sure you call on to the super.viewDidDisappear as well. To quote the documentation-
You can override this method to perform additional tasks associated
with dismissing or hiding the view. If you override this method, you
must call super at some point in your implementation.
This might ease your memory issues. Give it a try.
Related
I know that this question was asked a couple of times, but other solutions didn't work for me.
I have this model:
var notifications = [Notification]()
Notification:
let user: User (name, profileimage, etc)
let items: [Movies] (movie has image, name, etc)
So i display my notifications inside a tableview, each cell has profile info at the top and collectionview with items bellow.
Inside my tableviewcell, i have to reloadData of my collectionview to display correct movies. I know that probably reloadData method causes this lagging, but are there any solutions to avoid it?
TableViewcell:
var notification: Notification! {
didSet {
collectionView.reloadData();
}
}
I also tried this thing inside tablecell and call this method in willDisplayTableViewcell, but it doesn't help at all:
func setCollectionViewDataSourceDelegate(forRow row: Int) {
collectionView.delegate = self
collectionView.dataSource = self
collectionView.reloadData()
}
Images are loading using kingfisher, so it's fine in other places in my project.
userProfileImage.kf.setImage(
with: URL(string: profileImage),
options: [
.processor(DownsamplingImageProcessor(size: CGSize(width: 175, height: 175))),
.scaleFactor(UIScreen.main.scale),
.transition(.fade(0.2)),
]
)
I would comment out the code you have shown above as it will only get in the way and give false readings. My gut feeling is somehow you have managed to directly wire your notifications to your tableview / collection view and they are running on a background thread. What I would do to test this theory is wrap code anywhere where the UI is going to be updated with a perform on main thread like this
DispatchQueue.main.async { [unowned self] in
//Your UI update code within cellforRow / cellForItem (both table and collection view) Here
}
Try doing this one by one until you find the culprit and for a better solution try to refactor so you don't have to force this Main thread directive.
I have a table view in one view controller. I want to update the table view from another VC. I'm doing this using NotificationCenter like this:
In the table view VC:
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(self.updateTableView), name: NSNotification.Name(rawValue: "updateTableView"), object: nil)
}
#objc func updateTableView() {
print("in func")
DispatchQueue.main.async {
self.listTV.reloadData()
}
}
In the opened VC:
func reloadTV() {
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "updateTableView"), object: nil)
}
The print works, but the table view doesn't reload. I can only see it changing if I dismiss the VC with the table view and open it again.
I've followed the suggestions of other answers which is to use DispatchQueue, but that didn't make a difference. What am I missing?
Many thanks!
I would consider doing this by protocol and delegate instead of notifications...
This is how I do it.
When you call tableView.reloadData(). It has no effect if the tableView is hidden (isHidden == true). I believe the behavior is also the same when the tableView is effectively hidden by another ViewController (so effectively hidden).
Solution: A suggestion is to reload the tableView when the view is shown again. Few ways to do that.
one is in viewDidAppear (depends on how you transitioned between ViewControllers),
or
you can keep a reference to the tableView and after you dismiss the second ViewController (in which you were sending the notification) you provide the callback to reload the tableView. Roughly like the snippet, with self being the secondViewController you transitioned to. Dismiss that view
self.dismiss(animated: true, completion: {
self.tableView.reloadData()
}
or you can still use your notification and setup a flag and when the viewDidAppear, you then reloadData() inside viewDidAppear. However for this to work, you need to ensure that viewDidAppear is always called when the view is shown again (this will depend on how you transitioned between views).Simply override that method and print to verify.
There are other ways but the bottom line is tableView.reloadData() will be ignored if it is called when the tableView is not visible on the screen. My guess is it's an optimization made by Apple (no need to reload if no table is showing) or maybe a bug. I think they'll say it's a feature 😄
I suggest instead of using NotificationCenter, to instead set a Bool, tableViewNeedsUpdate, and check for the value of that Bool when the view with the UITableView is presented, and the UITableView is visible and able to accept reloadData() calls. After the reload is complete, set the variable back to false.
Description
I am trying to use NSSegmentedControls to transition between Child ViewControllers. The ParentViewController is located in Main.storyboard and the ChildViewControllers are located in Assistant.storyboard. Each ChildViewController has a SegmentedControl divided into 2 Segments and their primary use is to navigate between the ChildViewControllers. So they are set up as momentaryPushIn rather than selectOne. Each ChildViewController uses a Delegate to communicate with the ParentViewController.
So in the ParentViewController I added the ChildViewControllers as following:
/// The View of the ParentViewController configured as NSVisualEffectView
#IBOutlet var visualEffectView: NSVisualEffectView!
var assistantChilds: [NSViewController] {
get { return [NSViewController]() }
set(newValue) {
for child in newValue { self.addChild(child) }
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
addAssistantViewControllersToChildrenArray()
}
override func viewWillAppear() {
visualEffectView.addSubview(self.children[0].view)
self.children[0].view.frame = self.view.bounds
}
private func addAssistantViewControllersToChildrenArray() -> Void {
let storyboard = NSStoryboard.init(name: "Assistant", bundle: nil)
let exampleChild = storyboard.instantiateController(withIdentifier: "ExampleChild") as! ExampleChildViewController
let exampleSibling = storyboard.instantiateController(withIdentifier: "ExampleSibling") as! ExampleSiblingViewController
exampleChild.navigationDelegate = self
exampleSibling.navigationDelegate = self
assistantChilds = [exampleChild, exampleSibling]
}
So far so good. The ExampleChildViewController has an NSTextField instance. While I am in the scope of the TextField, I can trigger the action of the SegmentedControls. Its navigating forward and backward as it should. But once I leave the scope of the TextField I can still click the Segments, but they are not triggering any action. They should be able to navigate forward and backward even if the TextField is not the current "First Responder" of the application. I think I am missing something out here, I hope anyone can help me with this. I know the problem is not the NSSegmentedControl because I am seeing the same behavior with an NSButton, which is configured as Switch/Checkbox, in the SiblingViewController. I just don't have any idea anymore what I am doing wrong.
It`s my first time asking a question myself here, so I hope the way I am doing is fine for making progress with the solution. Let me know if I can do something better/different or if I need to provide more information about something.
Thanks in advance!
Additional Information
For the sake of completeness:
The ParentViewController itself is embedded in a ContainerView,
which is owned by the RootViewController. I can't imagine this does
matter in any way, but this way we are not missing something out.
I am actually not showing the navigation action, because I want to
keep it as simple as possible. Furthermore the action is not problem,
it does what I want it to do. Correct me if I am wrong with this.
Possible solutions I found while researching, which did not work for me:
Setting window.delegate of the ChildViewControllers to NSApp.windows.first?.delegate
Setting the ChildViewController to becomeFirstResponder in its func viewWillAppear()
visualEffectView.addSubview(self.children[0].view, positioned: NSWindow.OrderingMode.above, relativeTo: nil)
Related problems/topics I found while researching:
Basic segmented control not working
Adding and Removing Child View Controllers
NSSegmentedControl - Odd appearance when placed in blur view
How to set first responder to NSTextView in Swift?
How to use #selector in Swift 2.2 for the first responder
Accessing methods, actions and/or outlets from other controllers with swift
How to use Child View Controllers in Swift 4.0 programmatically
Container View Controllers
issues with container view
Control a NSTabViewController from parent View
How to detect when NSTextField has the focus or is it`s content selected cocoa
SOLUTION
let parentViewControllerInstance = self.parent as! ParentViewController
segmentedControl.target = parentViewControllerInstance
In my case I just had to set the delegate as the target of the sendAction method.
Background
Ok, after hours of reading the AppKit Documentation I am now able to answer my own question.
First, debugging the UI showed that the problem was definitely not in the ViewHierarchy.
So I tried to think about the nature of NSButton and NSSegmentedControl. At some point I noticed that both are subclasses of NSControl.
class NSSegmentedControl : NSControl
class NSButton : NSControl
The AppKit Documentation says:
Discussion
Buttons are a standard control used to initiate actions within your app. You can configure buttons with many different visual styles, but the behavior is the same. When clicked, a button calls the action method of its associated target object. (...) You use the action method to perform your app-specific tasks.
The bold text points to the key of the solution – of its associated target object. Typically I define the action of an control item like this:
button.action = #selector(someFunc(_:))
This causes the NSControl instance to call this:
func sendAction(_ action: Selector?, to target: Any?) -> Bool
Parameter Description from the documentation:
Parameters
theAction
The selector to invoke on the target. If the selector is NULL, no message is sent.
theTarget
The target object to receive the message. If the object is nil, the application searches the responder chain for an object capable of handling the message. For more information on dispatching actions, see the class description for NSActionCell.
In conclusion the NSControl instance, which was firing the action method (in my case the NSSegmentedControl), had no target to send its action to. So it was only able to send its action method across the responder chain - which obviously has been nil while the first responder was located in another view.
I am using this tutorial to implement a pull-to-refresh behavior with the RefreshControl. I am using a Navigation Bar. When using normal titles everything works good. But, when using "Prefer big titles" it doesn't work correctly as you can see in the following videos. Anyone knows why? The only change between videos is the storyboard check on "Prefer Large Titles".
I'm having the same problem, and none of the other answers worked for me.
I realised that changing the table view top constraint from the safe area to the superview fixed that strange spinning bug.
Also, make sure the constant value for this constraint is 0 🤯.
At the end what worked for me was:
In order to fix the RefreshControl progress bar disappearing bug with large titles:
self.extendedLayoutIncludesOpaqueBars = true
In order to fix the list offset after refreshcontrol.endRefreshing():
let top = self.tableView.adjustedContentInset.top
let y = self.refreshControl!.frame.maxY + top
self.tableView.setContentOffset(CGPoint(x: 0, y: -y), animated:true)
If you were using tableView.tableHeaderView = refreshControl or tableView.addSubView(refreshControl) you should try using tableView.refreshControl = refreshControl
It seems there are a lot of different causes that could make this happen, for me I had a TableView embedded within a ViewController. I set the top layout guide of the tableview to the superview with 0. After all of that still nothing until I wrapped my RefreshControl end editing in a delayed block:
DispatchQueue.main.async {
if self.refreshControl.isRefreshing {
DispatchQueue.main.asyncAfter(deadline: .now() + 1.0, execute: {
self.refreshControl.endRefreshing()
})
}
}
The only working solution for me is combining Bruno's suggestion with this line of code:
tableView.contentInsetAdjustmentBehavior = .always
I've faced the same problem. Call refreshControl endRefreshing before calling further API.
refreshControl.addTarget(controller, action: #selector(refreshData(_:)), for: .valueChanged)
#objc func refreshData(_ refreshControl: UIRefreshControl) {
refreshControl.endRefreshing()
self.model.loadAPICall {
self.tableView.reloadData()
}
}
The only solution that worked for me using XIBs was Bruno's one:
https://stackoverflow.com/a/54629641/2178888
However I did not want to use a XIB. I struggled a lot trying to make this work by code using AutoLayout.
I finally found a solution that works:
override func loadView() {
super.loadView()
let tableView = UITableView()
//configure tableView
self.view = tableView
}
I had this issue too, and i fixed it by embedded my scrollView (or tableView \ collectionView) inside stackView, and it's important that this stackView's top constraint will not be attached to the safeArea view (all the other constraints can). the top constraint should be connect to it's superview or to other view.
I was facing the same issue for very long, the only working solution for me was adding refresh control to the background view of tableview.
tableView.backgroundView = refreshControl
Short Answer
I fixed this by delaying calling to API until my collection view ends decelerating
Long Answer
I notice that the issue happens when refresh control ends refreshing while the collection view is still moving up to its original position. Therefore, I delay making API call until my collection view stops moving a.k.a ends decelerating. Here's a step by step:
Follow Bruno's suggestion
If you set your navigation bar's translucent value to false (navigationBar.isTranslucent = false), then you will have to set extendedLayoutIncludesOpaqueBars = true on your view controller. Otherwise, skip this.
Delay api call. Since I'm using RxSwift, here's how I do it.
collectionView.rx.didEndDecelerating
.map { [unowned self] _ in self.refreshControl.isRefreshing }
.filter { $0 == true }
.subscribe(onNext: { _ in
// make api call
})
.disposed(by: disposeBag)
After API completes, call to
refreshControl.endRefreshing()
Caveat
Do note that since we delay API call, it means that this whole pull-to-refresh process is not as quick as it could have been done without the delay.
Unfortunately, no advice helped. But I found a solution that helped me. Setting the transparency of the navigation bar helped.enter image description here
Problem can be solved if add tableview or scroll view as root view in UIViewController hierarchy (like in UITableViewController)
override func loadView() {
view = customView
}
where customView is UITableView or UICollectionView
i've got this type of problem :
With my app i'm able to connect my iPhone with a BLE device so when i connect their together i'm transported into an another view.
Into this view i've to check always if i'm connected yet in a thread func.
If my connection is lost i've to call the performSegueWithIdentifier method.
But... When i do it, xCode give me back a bad report that says :
This application is modifying the autolayout engine from a background
thread, which can lead to engine corruption and weird crashes. This
will cause an exception in a future release.
This is my short code :
override func viewDidLoad(){
super.ViewDidLoad()
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
while(true){
if(serial.connectedPeripheral == nil){
self.GoBackToBLE()
}
}
}
}
I want to precise that i can't use the method dispatch_get_main_queue because if i use that i can't do anything else into the view for example if i have a button I want to be able to press it and if i use dispatch_get_main_queue method i can't.
any suggestions? thanks a lot
You shouldn't do anything related to UI in dispatch_get_global_queue
you can split the things to run into 2 parts, 1 is related to UI other one is doing network calls/calculations etc.
override func viewDidLoad(){
super.ViewDidLoad()
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_main_queue(), { () -> Void in
// do the ui stuff here
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), { () -> Void in
// do everything which is not ui
})
})
}