Crash in modal view controller when swiping up on the controller. #27
Comments
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Hi Bob, I tried to reproduce the issue in the sample projects by presenting view controllers modally but it didn't happen:
@IBAction private func stackButtonTouched() {
present(ShapesViewController.instantiate(viewModel: ShapesViewModel(layouts: .stack)), animated: true, completion: nil)
} |
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I have a UINavigationController with a UIViewController that has a UIBarButtonItem that when selected presents the UIViewController with a CollectionView modally.
class BasicSnapshotCollectionViewCell: UICollectionViewCell, SnapshotTransformView {
var snapshotOptions = SnapshotTransformViewOptions(
pieceSizeRatio: .init(width: 0.25, height: 0.10),
piecesCornerRadiusRatio: .static(0.00),
piecesAlphaRatio: .aggregated([.rowOddEven(
0.20,
0.00,
increasing: false
), .columnOddEven(
0.00,
0.20,
increasing: false
)], +),
piecesTranslationRatio: .rowOddEven(
.init(x: -0.15, y: 0.00),
.init(x: 0.15, y: 0.00),
increasing: false
),
piecesScaleRatio: .columnOddEven(
.init(width: 0.10, height: 0.40),
.init(width: 0.40, height: 0.10),
increasing: false
),
containerScaleRatio: 0.20,
containerTranslationRatio: .init(x: 1.00, y: 0.00)
)
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder: NSCoder) {
super.init(coder: coder)
}
}
class ViewController: UIViewController, UICollectionViewDataSource {
@IBOutlet weak var collectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
setupCollectionView()
}
private func setupCollectionView() {
let layout = CollectionViewPagingLayout()
collectionView.collectionViewLayout = layout
collectionView.isPagingEnabled = true
collectionView.dataSource = self
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
collectionView?.performBatchUpdates({
self.collectionView.collectionViewLayout.invalidateLayout()
})
}
func collectionView(
_ collectionView: UICollectionView,
numberOfItemsInSection section: Int
) -> Int {
return 10
}
func collectionView(
_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.row % 2 == 0 {
return collectionView.dequeueReusableCell(withReuseIdentifier: "redCell", for: indexPath) as! redCollectionViewCell
} else {
return collectionView.dequeueReusableCell(withReuseIdentifier: "blueCell", for: indexPath) as! blueCollectionViewCell
}
}
} |
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I made a new project with Xcode 11.6, added the library, and this code: import UIKit
import CollectionViewPagingLayout
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
self.window = UIWindow(frame: UIScreen.main.bounds)
let nav = UINavigationController()
nav.viewControllers = [MainVC()]
window?.rootViewController = nav
window?.makeKeyAndVisible()
return true
}
}
class MainVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = .green
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "present", style: .done, target: self, action: #selector(presentVC))
}
@objc func presentVC() {
present(ViewController(), animated: true, completion: nil)
}
}
class ViewController: UIViewController, UICollectionViewDataSource {
weak var collectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: CollectionViewPagingLayout())
view.addSubview(collectionView)
self.collectionView = collectionView
setupCollectionView()
}
private func setupCollectionView() {
collectionView.isPagingEnabled = true
collectionView.dataSource = self
collectionView.register(BasicSnapshotCollectionViewCell.self, forCellWithReuseIdentifier: "redCell")
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
collectionView.frame = .init(x: 0, y: 0, width: view.frame.width, height: view.frame.height)
collectionView?.performBatchUpdates({
self.collectionView.collectionViewLayout.invalidateLayout()
})
}
func collectionView(
_ collectionView: UICollectionView,
numberOfItemsInSection section: Int
) -> Int {
return 10
}
func collectionView(
_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
collectionView.dequeueReusableCell(withReuseIdentifier: "redCell", for: indexPath) as! BasicSnapshotCollectionViewCell
}
}
class BasicSnapshotCollectionViewCell: UICollectionViewCell, SnapshotTransformView {
var snapshotOptions = SnapshotTransformViewOptions(
pieceSizeRatio: .init(width: 0.25, height: 0.10),
piecesCornerRadiusRatio: .static(0.00),
piecesAlphaRatio: .aggregated([.rowOddEven(
0.20,
0.00,
increasing: false
), .columnOddEven(
0.00,
0.20,
increasing: false
)], +),
piecesTranslationRatio: .rowOddEven(
.init(x: -0.15, y: 0.00),
.init(x: 0.15, y: 0.00),
increasing: false
),
piecesScaleRatio: .columnOddEven(
.init(width: 0.10, height: 0.40),
.init(width: 0.40, height: 0.10),
increasing: false
),
containerScaleRatio: 0.20,
containerTranslationRatio: .init(x: 1.00, y: 0.00)
)
override init(frame: CGRect) {
super.init(frame: frame)
setupView()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
setupView()
}
func setupView() {
let view = UIView()
contentView.addSubview(view)
view.backgroundColor = .red
view.frame = .init(x: 100,y: 100,width: 100,height: 100)
}
} |
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I used the Mac app to create the layout clicked save as a project (Xcode 11.7). I then added a new storyboard and then created the controllers and UI elements in Storyboard. Build and run the project and when the collectionView loads drag from the bottom of the view to the top. If I keep everything the same and just change the collection view layout it will not crash. From:
To:
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We cannot say the problem is related to the layout because by changing the layout it's fixable, the flow layout behaves differently, for instance, there might be no need to access to CollectionView in the flow layout. anyway, it's still not reproducible for me, but I think the problem is coming from weak var collectionView: UICollectionView!
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
DispatchQueue.main.async { [weak self] in
self?.collectionView?.performBatchUpdates({ [weak self] in
self?.collectionView?.collectionViewLayout.invalidateLayout()
})
}
} |
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Interesting it doesn't happen for you, I can get it to happen in every project I add it to, whether running in a simulator or on a physical device. As mentioned above I did narrow it down to |
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Cool, I'll change the code in the samples and the generated code! can you share a simple project here or via email: Khorsandi@me.com? |
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Okay, thank you. I will send the project soon. Another question, is there a way to avoid invalidating the layout when it first launches? I am not having crashes anymore but I see the view partially come up from the bottom as its about to present and then fully come up. So it looks like it glitches almost. |
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Are you sure that is because of invalidating layout? |
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I have sent an email with the sample project I modified. It will crash when you pull up on the initial controller without first paging to any other cell. The issue where the view starts to be presented and then the layout invalidates and is presented again is not visible in this sample. In my main project that creates and presents everything the same way but has a more complex layout it is visible. |
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Again the crash is fixed with this change to invalidateLayout in previous comments. |
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Thanks for the email, I can replicate the issue now. meanwhile, you can set the cell height manually instead of constraint to the superview |
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There is a new method for addressing this issue where you can implement and specify when a snapshot can be reused. public protocol SnapshotTransformView: TransformableView {
/// Check if the snapshot can be reused
func canReuse(snapshot: SnapshotContainerView) -> Bool
}check the new version |
Crashes when swiping up on the controller when having a collectionView with this layout presented modally. Only happens when the view is initially loaded and the first thing you do is swipe up.
Will not crash when you swipe to a different card and swipe up. When you swipe up and it doesn't crash you get other cards reloading from the top left and expanding back into place every time you swipe.
If you comment out viewDidLayoutSubviews code it will not crash but other issues are present.
Error:
[UICollectionViewData isIndexPathValid:validateItemCounts:]: message sent to deallocated instance
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