problem knowing the data of a particular camera - arrays

I am making a practice simple app as I am learning swiftUI. My current problem seems to lie in this function:
variables
#State var cameras: [Camera] = []
#State var angle: Double = 0.0
func fetchAngle(){
COLLECTION_CAMERAS.whereField("active", isEqualTo: true).addSnapshotListener { snapshot, _ in
self.cameras = snapshot!.documents.compactMap({ try? $0.data(as: Camera.self)})
self.angle = cameras[0].angle
}
There can only be one active camera out of the three.
I know its bad practice but all the program is in the MainView() for simplicity, after I finish debugging I will use MVVM.
The angle variable is #Published, because I want to redraw the user interface when its updated.
The there is a set of 3 buttons and each time I press one of them, successfully update in firebase the active field to true or false.
As there are three cameras I fetch the collection and wish to only get the camera where the active field is true. So far so good, my problem starts (I think) with this code self.angle = cameras[0].angle. What I wish to achieve is to be able to set self.angle with the angle of the only camera that has active == true.

Related

How to update UI with a viewModel for byte arrays and lists in Kotlin/Jetpack Compose?

So the problem I am facing is that when the viewModel data updates it doesn't seems to update the state of my bytearrays: ByteArray by (mutableStateOf) and mutableListOf()
When I change pages/come back to the page it does update them again. How can get the view to update for things like lists and bytearrays
Is mutableStateOf the wrong way to update bytearrays and lists? I couldn't really find anything useful.
Example of byte array that doesn't work (using this code with a Float by mutableStateOf works!).
How I retrieve the data in the #Composable:
val Data = BluetoothMonitoring.shared.Data /*from a viewModel class, doesn't update when Data / bytearray /list changes, only when switching pages in app.*/
Class:
class BluetoothMonitoring : ViewModel(){
companion object {
val shared = BluetoothMonitoring()
}
var Data : ByteArray by mutableStateOf( ByteArray(11) { 0x00 })
}
Any help is appreciated and thanks in advance!
You seem to come from IOS/Swift where using Shared objects is a common pattern
In Android, you're not supposed to create a viewmodel instance by hand, you are supposed to use ViewModelFactory, or compose viewModel() function. The ViewModel object basically preserves some data for you across activity recompositions, i.e. when activity is paused, resumed etc
The general good way of structuring your app is using UDF (Unidirectional Data Flow) where, data flows upwards towards the view/composable and events flow downwards towards the viewmodel, data layer etc. We use something called as Flow which is a reactive data stream, which updates the listener whenever some value changes
Keeping in mind these two points, I've created a very brief way of how you could restructure your code, so that it almost always works. Please adapt accordingly to your logic
class MyViewModel: ViewModel(){
// Declare a flow in the viewModel
var myData = MutableStateFlow(0)
fun modifyMyData(newData: Int){
myData = newData
}
}
And in your composable view layer
#Composable
fun YourComposable(){
val myViewModel = viewModel()
val myUiState by myViewModel.myData.collectAsState()
// Now use your value, and change it, it will be changed accordingly and updated everywhere
}
I also recommend reading this codelab
How I handle byte arrays over Bluetooth with kotlin and Android.
I'm talking sic (communication) to arduino over bluetooth in the app I'm making. Kotlin likes Byte and Arduino likes UBYTE so I do all of those translations in the app because Kotlin threads are inline code easy and the phone has more power for such things.
Add toByte() to everthing that is outbound. <- (actual solution)
outS[8] = Color.alpha(word.color).toByte()
outS[9] = Color.red(word.color).toByte()
outS[10] = Color.green(word.color).toByte()
outS[11] = Color.blue(word.color).toByte()
outS[12] = 0.toByte()
outS[13] = 232.toByte()
outS[14] = 34.toByte()
outS[15] = 182.toByte()
//outS[16] = newline working without a newLine!
// outS[16] = newline
val os = getMyOutputStream()
if (os != null) {
os.write(outS)
}
For inbound data...I have to change everything to UByte. <- (actual solution)
val w: Word = wordViewModel.getWord(i)
if (w._id != 0) {
w.rechecked = (byteArray[7].toInt() != 0)
w.recolor = Color.argb(
byteArray[8].toUByte().toInt(),
byteArray[9].toUByte().toInt(),
byteArray[10].toUByte().toInt(),
byteArray[11].toUByte().toInt()
)
//finally update the word
wordViewModel.update(w)
}
My Youtube channel is about model trains not coding there some android and electronics in there. And a video of bluetooth arduino android is coming soon like tonight or tomorrow soon. I've been working on the app for just over a month using it to learn Kotlin. The project is actually working but I have to do the bluetooth connection manually the app actually controls individual neopixels for my model train layout.

ARKit - ARRreferenceImage tracking

I'm playing around with ARReferenceImages in ARKit and I'm trying to add an SCNNode when a reference image is recognised and then leave that node in place regardless of whether the same reference image is then recognised elsewhere.
I can add my SCNode correctly, but if I move my marker it picks it up again and moves my placed node to the position of the marker.
My code to add is as follows:
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
guard let imageAnchor = anchor as? ARImageAnchor else { return }
let referenceImage = imageAnchor.referenceImage
print("MAPNODE IS NIL = \(self.mapNode == nil)")
updateQueue.async {
if self.mapNode == nil {
// Create a plane to visualize the initial position of the detected image.
let plane = SCNPlane(width: 1.2912,
height: 1.2912)
let planeNode = SCNNode(geometry: plane)
planeNode.opacity = 1
/*
`SCNPlane` is vertically oriented in its local coordinate space, but
`ARImageAnchor` assumes the image is horizontal in its local space, so
rotate the plane to match.
*/
planeNode.eulerAngles.x = -.pi / 2
self.mapNode = planeNode
/*
Image anchors are not tracked after initial detection, so create an
animation that limits the duration for which the plane visualization appears.
*/
// Add the plane visualization to the scene.
node.addChildNode(planeNode)
}
}
}
reading the docs here https://developer.apple.com/documentation/arkit/recognizing_images_in_an_ar_experience#2958517 it states that
Apply Best Practices
This example app simply visualizes where ARKit detects each reference
image in the user’s environment, but your app can do much more. Follow
the tips below to design AR experiences that use image detection well.
Use detected images to set a frame of reference for the AR scene.
Instead of requiring the user to choose a place for virtual content,
or arbitrarily placing content in the user’s environment, use detected
images to anchor the virtual scene. You can even use multiple detected
images. For example, an app for a retail store could make a virtual
character appear to emerge from a store’s front door by recognizing
posters placed on either side of the door and then calculating a
position for the character directly between the posters.
Note
Use the ARSession setWorldOrigin(relativeTransform:) method to
redefine the world coordinate system so that you can place all anchors
and other content relative to the reference point you choose.
Design your AR experience to use detected images as a starting point
for virtual content. ARKit doesn’t track changes to the position or
orientation of each detected image. If you try to place virtual
content that stays attached to a detected image, that content may not
appear to stay in place correctly. Instead, use detected images as a
frame of reference for starting a dynamic scene. For example, your app
might recognize theater posters for a sci-fi film and then have
virtual spaceships appear to emerge from the posters and fly around
the environment.
So I tried setting my world transform to be equal to the transform of my image anchor
self.session.setWorldOrigin(relativeTransform: imageAnchor.transform)
However my mapNode follows the imageAnchor where ever it moves. I haven't implemented the renderer update method so I'm not sure why this keeps moving.
I'm assuming that the setWorldOrigin method is constantly updating to the imageAnchor.transform and not just that moment in time, which is weird as that code is only called once. Any ideas?
If you want to add the mapNode at the position of the ARImageAnchor you could set the position of your mapNode at the transform of the ARImageAnchor and add it to the scene but not linked to the reference image if that makes sense.
This could be done like so:
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
//1. If Out Target Image Has Been Detected Than Get The Corresponding Anchor
guard let currentImageAnchor = anchor as? ARImageAnchor else { return }
//2. An ImageAnchor Is Only Added Once For Each Identified Target
print("Anchor ID = \(currentImageAnchor.identifier)")
//3. Add An SCNNode At The Position Of The Identified ImageTarget
let nodeHolder = SCNNode()
let nodeGeometry = SCNBox(width: 0.02, height: 0.02, length: 0.02, chamferRadius: 0)
nodeGeometry.firstMaterial?.diffuse.contents = UIColor.cyan
nodeHolder.geometry = nodeGeometry
nodeHolder.position = SCNVector3(currentImageAnchor.transform.columns.3.x,
currentImageAnchor.transform.columns.3.y,
currentImageAnchor.transform.columns.3.z)
augmentedRealityView?.scene.rootNode.addChildNode(nodeHolder)
}
In another part of your question you seem to imply that you want to detect multiple occurrences of the same image. I could be wrong but I think the only way to do this is to remove the corresponding ARImageAnchor for the reference image, which can be done like so (by adding it at the end of the last code snippet):
augmentedRealitySession.remove(anchor: currentImageAnchor)
The issue here is that once the ARImageAnchor is removed, any time it is detected again, you would have to handle whether content should be added, which is tricky since the ARImageAnchor.identifier is always the same for the referenceImage regardless of whether it is removed and then re-added thus making it difficult to store in a dictionary etc. As such depending on your needs you would then need to find a way to determine if content existed at that location and whether to re add it etc.
The last part of your question about setWorldOrigin seems a bit odd like you said, but maybe you could add a Bool to prevent it from potentially changing e.g:
var hasSetWorldOrigin = false
Then based on this you could ensure that it is only set once e.g:
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
//1. If Out Target Image Has Been Detected Than Get The Corresponding Anchor
guard let currentImageAnchor = anchor as? ARImageAnchor else { return }
//2. If We Havent Set The World Origin Set It Based On The ImageAnchorTranform
if !hasSetWorldOrigin{
self.augmentedRealitySession.setWorldOrigin(relativeTransform: currentImageAnchor.transform)
hasSetWorldOrigin = true
//3. Create Two Nodes To Add To The Scene And Distribute Them
let nodeHolderA = SCNNode()
let nodeGeometryA = SCNBox(width: 0.04, height: 0.04, length: 0.04, chamferRadius: 0)
nodeGeometryA.firstMaterial?.diffuse.contents = UIColor.green
nodeHolderA.geometry = nodeGeometryA
let nodeHolderB = SCNNode()
let nodeGeometryB = SCNBox(width: 0.04, height: 0.04, length: 0.04, chamferRadius: 0)
nodeGeometryB.firstMaterial?.diffuse.contents = UIColor.red
nodeHolderB.geometry = nodeGeometryB
if let cameraTransform = augmentedRealitySession.currentFrame?.camera.transform{
nodeHolderA.simdPosition = float3(cameraTransform.columns.3.x,
cameraTransform.columns.3.y,
cameraTransform.columns.3.z)
nodeHolderB.simdPosition = float3(cameraTransform.columns.3.x + 0.2,
cameraTransform.columns.3.y,
cameraTransform.columns.3.z)
}
augmentedRealityView?.scene.rootNode.addChildNode(nodeHolderA)
augmentedRealityView?.scene.rootNode.addChildNode(nodeHolderB)
}
}
Hopefully my answer will provide a useful starting point to you assuming of course I have interpreted your question correctly,

How can I assert that a value of a string is equal to one of any string values in an array using XCTAssert in Swift?

I'm new to Swift and followed a simple tutorial to make a magic 8 ball Cocoa App that every time I click the ball it shows a different piece of advice. I am now trying to practice my UI automated tests by asserting (XCTAssert) that the "Piece of Advice" label is equal to one of the string values in my array.
My array looks like this and is in my ViewController.swift:
var adviceList = [
"Yes",
"No",
"Tom says 'do it!'",
"Maybe",
"Try again later",
"How can I know?",
"Totally",
"Never",
]
How can I make an assertion in my UITests.swift file that asserts that the string that is shown is equal to one of the string values in the array above?
It's possible that you're asking how to access application state from a UI test, or just in general UI testing.
I think it's a pretty interesting question so I'm going to answer because it's something that I don't know a lot about and hopefully will prompt other people to chime in and correct.
Background: A basic Magic 8 Ball project
I set up a basic project with a view controller that contains two views: a label and a button. Tapping the button updates the label text with a random message:
import UIKit
struct EightBall {
static let messages = ["Yes", "No", "It's not certain"]
var newMessage: String {
let randomIndex = Int(arc4random_uniform(UInt32(EightBall.messages.count)))
return EightBall.messages[randomIndex]
}
}
class ViewController: UIViewController {
let ball = EightBall()
#IBOutlet weak var messageLabel: UILabel!
#IBAction func shakeBall(_ sender: Any) {
messageLabel.text = ball.newMessage
}
}
A basic UI test
Here's a commented UI test showing how to automate tapping on the button, and grabbing the value of the label, and then checking that the value of the label is a valid message.
import XCTest
class MagicUITests: XCTestCase {
// This method is called before the invocation of each test method in the class.
override func setUp() {
super.setUp()
// In UI tests it is usually best to stop immediately when a failure occurs.
continueAfterFailure = true
// UI tests must launch the application that they test. Doing this in setup will make sure it happens for each test method.
XCUIApplication().launch()
}
func testValidMessage() {
// Grab reference to the application
let app = XCUIApplication()
// #1
// Grab reference to the label with the accesability identifier 'MessageLabel'
let messagelabelStaticText = app.staticTexts["MessageLabel"]
// Tap the button with the text 'Shake'
app.buttons["Shake"].tap()
// get the text of the label
let messageLabelText = messagelabelStaticText.label
// #2
// check if the text in the label matches one of the allowed messages
let isValidMessage = EightBall.messages.contains(messageLabelText)
// test will fail if the message is not valid
XCTAssert(isValidMessage)
}
}
At #1 The approach that I'm using to get the label is to access the labels accessibilityIdentifier property. For this project I entered this through storyboard, but if you're setting your views up in code you can directly set the accessibilityIdentifier property yourself.
The other thing that's confusing here is that to get access to elements in the view you're not navigating the view hierarchy, but a proxy of the hierarchy, which is why the syntax to get a label is the odd 'staticTexts' (The references at the bottom of the post explain this in more detail).
For #2 I'm inspecting the structure defined in my project. In a unit test you could access this my importing #testable import ProjectName but unfortunately this approach doesn't work for UI Test.
Instead, you'll have to make sure that any source file you want to access from the UI test is included as a target. You can do this in Xcode from this panel by checking the name of your UI test:
More UI testing references:
UI Testing Intro: http://www.mokacoding.com/blog/xcode-7-ui-testing/
UI Testing Cheat Sheet: http://masilotti.com/ui-testing-cheat-sheet/

Synchronously play videos from arrays using actionscript 3

I am developing an AIR application using Actionscript 3.0. The application loads two native windows on two separate monitors. Monitor 1 will play a video, and monitor 2 will synchronously play an overlayed version of the same video (i.e. infrared). Presently, I am hung up with figuring out the best way to load the videos. I'm thinking about using arrays, but am wondering, if I do, how can I link arrays so to link a primary scene to its secondary overlay videos.
Here is my code so far. The first part of it creates the 2 native full-screen windows, and then you'll see where I started coding the arrays at the bottom:
package
{
import flash.display.NativeWindow;
import flash.display.NativeWindowInitOptions;
import flash.display.NativeWindowSystemChrome;
import flash.display.Screen;
import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageDisplayState;
import flash.display.StageScaleMode;
public class InTheAirNet_MultiviewPlayer extends Sprite {
public var secondWindow:NativeWindow;
public function InTheAirNet_MultiviewPlayer() {
// Ouput screen sizes and positions (for debugging)
for each (var s:Screen in Screen.screens) trace(s.bounds);
// Make primary (default) window's stage go fullscreen
stage.align = StageAlign.TOP_LEFT;
stage.scaleMode = StageScaleMode.NO_SCALE;
stage.displayState = StageDisplayState.FULL_SCREEN_INTERACTIVE;
stage.color = 0xC02A2A; // red
// Create fullscreen window on second monitor (check if available first)
if (Screen.screens[1]) {
// Second window
var nwio:NativeWindowInitOptions = new NativeWindowInitOptions();
nwio.systemChrome = NativeWindowSystemChrome.NONE;
secondWindow = new NativeWindow(nwio);
secondWindow.bounds = (Screen.screens[1] as Screen).bounds;
secondWindow.activate();
// Second window's stage
secondWindow.stage.align = StageAlign.TOP_LEFT;
secondWindow.stage.scaleMode = StageScaleMode.NO_SCALE;
secondWindow.stage.displayState = StageDisplayState.FULL_SCREEN_INTERACTIVE;
secondWindow.stage.color = 0x387D19; // green
}
//Create array of PRIMARY scenes
var primary:Array = ["scene1.f4v", "scene2.f4v"];
//Create array of SECONDARY scenes for scene1
var secondary1:Array = ["scene1A.f4v", "scene1B.f4v"];
//Create array of SECONDARY scenes for scene2
var secondary2:Array = ["scene2A.f4v", "scene2B.f4v"];
}
}
}
EDIT: Users will cycle through overlays using LEFT and RIGHT on the keyboard, and will cycle through the scenes using UP and DOWN.
Use a generic Object for each video, store each in an array, and then store the secondary videos in an array within each object:
var videos:Array = [
{
primary:'video1.mp4',
secondary:[
'overlay101.mp4',
'overlay102.mp4'
]
},
{
primary:'video2.mp4',
secondary:[
'overlay201.mp4',
'overlay202.mp4'
]
}
{
primary:'video3.mp4',
secondary:[
'overlay301.mp4',
'overlay302.mp4'
]
}
]
Then when you to play a video, you can loop through the videos array. Each object has a primary video and its associated secondary videos. You could take it a step further, as well, and use the object to store metadata or store more Objects within the secondary array, rather than strings.
EDIT: Quick response to the first comment
In Object-Oriented Programming (OOP) languages, everything is an object. Every single class, every single function, every single loop, every single variable is an object. Classes generally extend a base class, which is called Object in AS3.
The Object is the most basic, most primitive type of object available — it is simply a list of name:value pairs, sometimes referred to as a dictionary. So you can do the following:
var obj:Object = {hello:'world'};
trace(obj.hello); // output 'world'
trace(obj['hello']); // output 'world'
trace(obj.hasOwnProperty('hello')); //output true (obj has a property named 'hello')
What I did was create one of these objects for each video and then save them to an array. So say you wanted to trace out primary and find out how many videos were in secondary, you would do this:
for (var i:int = 0; i < videos.length; i++) {
var obj:Object = videos[i];
trace('Primary: ' + obj.primary); // for video 1, output 'video1.mp4'
trace('Secondary Length: ' + obj.secondary.length); // for video1, output 2
}
That should show you how to access the values. An dictionary/Object is the correct way to associate data and the structure I supplied is very simple, but exactly what you need.
What we're talking about is the most basic fundamentals of OOP programming (which is what AS3 is) and using dot-syntax, used by many languages (everything from AS3 to JS to Java to C++ to Python) as a way of accessing objects stored within other objects. You really need to read up on the basics of OOP before moving forward. You seem to be missing the fundamentals, which is key to writing any application.
I can't perfectly understand what you're trying to do, but have you thought about trying a for each loop? It would look something like...
prim1();
function prim1():void
{
for each (var vid:Video in primary)
{
//code to play the primary video here
}
for each (var vid:Video in secondary1)
{
//code to play the secondary video here
}
}
Sorry if it's not what you wanted, but what I understood from the question is that you're trying to play the both primary and secondary videos at the same time so that they're in synch. Good luck with your program ^^

initialLayoutAttributesForAppearingItemAtIndexPath fired for all visible cells, not just inserted cells

Has anyone seen a decent answer to this problem?
initialLayoutAttributesForAppearingItemAtIndexPath seems to be being called for all visible cells, not just the cell being inserted. According to Apple's own docs:
For moved items, the collection view uses the standard methods to retrieve the item’s updated layout attributes. For items being inserted or deleted, the collection view calls some different methods, which you should override to provide the appropriate layout information
Which doesn't sound like what is happening... the other cells aren't being inserted, they are being moved, but it's calling initialLayoutAttributesForAppearingItemAtIndexPath for the ones being moved too.
I have seen work arounds using prepareForCollectionViewUpdates: to trace which indexPaths are being updated and only changing those, but this seems a bit odd that it's going agains their own docs. Has anyone else found a better way around this?
I found this blog post by Mark Pospesel to be helpful.
The author also fixed WWDC CircleLayout sample and posted it on Github.
Methods of interest:
- (void)prepareForCollectionViewUpdates:(NSArray *)updateItems
{
// Keep track of insert and delete index paths
[super prepareForCollectionViewUpdates:updateItems];
self.deleteIndexPaths = [NSMutableArray array];
self.insertIndexPaths = [NSMutableArray array];
for (UICollectionViewUpdateItem *update in updateItems)
{
if (update.updateAction == UICollectionUpdateActionDelete)
{
[self.deleteIndexPaths addObject:update.indexPathBeforeUpdate];
}
else if (update.updateAction == UICollectionUpdateActionInsert)
{
[self.insertIndexPaths addObject:update.indexPathAfterUpdate];
}
}
}
- (void)finalizeCollectionViewUpdates
{
[super finalizeCollectionViewUpdates];
// release the insert and delete index paths
self.deleteIndexPaths = nil;
self.insertIndexPaths = nil;
}
// Note: name of method changed
// Also this gets called for all visible cells (not just the inserted ones) and
// even gets called when deleting cells!
- (UICollectionViewLayoutAttributes *)initialLayoutAttributesForAppearingItemAtIndexPath:(NSIndexPath *)itemIndexPath
{
// Must call super
UICollectionViewLayoutAttributes *attributes = [super initialLayoutAttributesForAppearingItemAtIndexPath:itemIndexPath];
if ([self.insertIndexPaths containsObject:itemIndexPath])
{
// only change attributes on inserted cells
if (!attributes)
attributes = [self layoutAttributesForItemAtIndexPath:itemIndexPath];
// Configure attributes ...
attributes.alpha = 0.0;
attributes.center = CGPointMake(_center.x, _center.y);
}
return attributes;
}
// Note: name of method changed
// Also this gets called for all visible cells (not just the deleted ones) and
// even gets called when inserting cells!
- (UICollectionViewLayoutAttributes *)finalLayoutAttributesForDisappearingItemAtIndexPath:(NSIndexPath *)itemIndexPath
{
// So far, calling super hasn't been strictly necessary here, but leaving it in
// for good measure
UICollectionViewLayoutAttributes *attributes = [super finalLayoutAttributesForDisappearingItemAtIndexPath:itemIndexPath];
if ([self.deleteIndexPaths containsObject:itemIndexPath])
{
// only change attributes on deleted cells
if (!attributes)
attributes = [self layoutAttributesForItemAtIndexPath:itemIndexPath];
// Configure attributes ...
attributes.alpha = 0.0;
attributes.center = CGPointMake(_center.x, _center.y);
attributes.transform3D = CATransform3DMakeScale(0.1, 0.1, 1.0);
}
return attributes;
}
You're not alone. The UICollectionViewLayout header file comments make things a little clearer.
For each element on screen before the invalidation,
finalLayoutAttributesForDisappearingXXX will be called and an
animation setup from what is on screen to those final attributes.
For each element on screen after the invalidation,
initialLayoutAttributesForAppearingXXX will be called an an animation
setup from those initial attributes to what ends up on screen.
Basically finalLayoutAttributesForDisappearingItemAtIndexPath is called for each item on screen before the animation block starts, and initialLayoutAttributesForAppearingItemAtIndexPath is called for each item after the animation block ends. It's up to you to cache the array of UICollectionViewUpdateItem objects sent in prepareForCollectionViewUpdates so you know how to setup the initial and final attributes. In my case I cached the previous layout rectangles in prepareLayout so I knew the correct initial positions to use.
One thing that stumped me for a while is you should use super's implementation of initialLayoutAttributesForAppearingItemAtIndexPath and modify the attributes it returns. I was just calling layoutAttributesForItemAtIndexPath in my implementation, and animations weren't working because the layout positions were different.
If you've subclassed UICollectionViewFlowLayout, you can call the super implementation. Once you've got the default initial layout, you can check for an .alpha of 0. If alpha is anything other than 0, the cell is being moved, if it's 0 it's being inserted.
Bit of a hack, I know, but it works 👍.
Swift 2.0 implementation follows:
override func initialLayoutAttributesForAppearingItemAtIndexPath(itemIndexPath: NSIndexPath) -> UICollectionViewLayoutAttributes? {
guard let attributes = super.initialLayoutAttributesForAppearingItemAtIndexPath(itemIndexPath) where attributes.alpha == 0 else {
return nil
}
// modify attributes for insertion here
return attributes
}
Make sure you're using new method signature in Swift 3. Autocorrection doesn't work for this method:
func initialLayoutAttributesForAppearingItem(at itemIndexPath: IndexPath) -> UICollectionViewLayoutAttributes?

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