Here's what I want to do , when I click on my button I want to jump the top but when I click on the button my app crashes.
#IBAction func addToCart(_ sender: UIButton) {
if quantitylbl.text == "0" {
dismiss(animated: true)
}
// Save in to userdefault
let section = sender.tag / 100
let row = sender.tag % 100
let dict = arrayCategory[section] as? NSDictionary
let subLimit = getStringValueFromAPIValue(apiValue: dict?.value(forKey: "limit"), defaultValue: "")
let cell = self.tableView.cellForRow(at: IndexPath(row: row, section: section)) as! CustomizationDropDownTableViewCell
if self.section_quantity[section] < Int(truncating: subLimit.numberValue!) {
cell.btnDropdown.becomeFirstResponder()
}
}
let subLimit = getStringValueFromAPIValue(apiValue: dict?.value(forKey: "limit"), defaultValue: "")
let cell = self.tableView.cellForRow(at: IndexPath(row: row, section: section)) as! CustomizationDropDownTableViewCell
I'm not sure what exact problem makes your App crash. Try to make some breakpoints in your code. I think there might be a problem with the optional issues.
The subLimit is optional, so make sure it has a value when forced unwrapping. Int(truncating: subLimit.numberValue!)
Also, use the forced form of the type cast operator (as!) only when you are sure that the downcast will always succeed.
See Apple's Swift document. https://docs.swift.org/swift-book/LanguageGuide/TypeCasting.html
Related
A Section may contain 1 header, many content items and 1 footer.
For DiffableDataSource, most of the online examples, are using enum to represent Section. For instance
func applySnapshot(_ animatingDifferences: Bool) {
var snapshot = Snapshot()
snapshot.appendSections([.MainAsEnum])
snapshot.appendItems(filteredTabInfos, toSection: .MainAsEnum)
dataSource?.apply(snapshot, animatingDifferences: animatingDifferences)
}
However, when the Section has a dynamic content footer, we may need to use struct to represent Section. For instance
import Foundation
struct TabInfoSection {
// Do not include content items [TabInfo] as member of Section. If not, any mutable
// operation performed on content items, will misguide Diff framework to throw
// away entire current Section, and replace it with new Section. This causes
// flickering effect.
var footer: String
}
extension TabInfoSection: Hashable {
}
But, how are we suppose to update only footer?
The current approach provided by
DiffableDataSource: Snapshot Doesn't reload Headers & footers is not entirely accurate
If I try to update footer
class TabInfoSettingsController: UIViewController {
…
func applySnapshot(_ animatingDifferences: Bool) {
var snapshot = Snapshot()
let section = tabInfoSection;
snapshot.appendSections([section])
snapshot.appendItems(filteredTabInfos, toSection: section)
dataSource?.apply(snapshot, animatingDifferences: animatingDifferences)
}
var footerValue = 100
extension TabInfoSettingsController: TabInfoSettingsItemCellDelegate {
func crossButtonClick(_ sender: UIButton) {
let hitPoint = (sender as AnyObject).convert(CGPoint.zero, to: collectionView)
if let indexPath = collectionView.indexPathForItem(at: hitPoint) {
// use indexPath to get needed data
footerValue = footerValue + 1
tabInfoSection.footer = String(footerValue)
//
// Perform UI updating.
//
applySnapshot(true)
}
}
}
I will get the following flickering outcome.
The reason of flickering is that, the diff framework is throwing entire old Section, and replace it with new Section, as it discover there is change in TabInfoSection object.
Is there a good way, to update footer in Section via DiffableDataSource without causing flickering effect?
p/s The entire project source code can be found in https://github.com/yccheok/ios-tutorial/tree/broken-demo-for-footer-updating under folder TabDemo.
Have you thought about making a section only for the footer? So that way there's no reload, when it flickers, since it's technically not apart of the problematic section?
There is a fast fix for it, but you will loose the animation of the tableview. In TabInfoSettingsController.swift you can force false the animations in this function:
func applySnapshot(_ animatingDifferences: Bool) {
var snapshot = Snapshot()
let section = tabInfoSection;
snapshot.appendSections([section])
snapshot.appendItems(filteredTabInfos, toSection: section)
dataSource?.apply(snapshot, animatingDifferences: false)
}
You will not see the flickering effect but you will loose the standard animation.
if you want to update only collectionview footer text then make it variable of TabInfoSettingsFooterCell.
var tableSection: TabInfoSettingsFooterCell?
DataSource
func makeDataSource() -> DataSource {
let dataSource = DataSource(
collectionView: collectionView,
cellProvider: { (collectionView, indexPath, tabInfo) -> UICollectionViewCell? in
guard let tabInfoSettingsItemCell = collectionView.dequeueReusableCell(
withReuseIdentifier: TabInfoSettingsController.tabInfoSettingsItemCellClassName,
for: indexPath) as? TabInfoSettingsItemCell else {
return nil
}
tabInfoSettingsItemCell.delegate = self
tabInfoSettingsItemCell.reorderDelegate = self
tabInfoSettingsItemCell.textField.text = tabInfo.getPageTitle()
return tabInfoSettingsItemCell
}
)
dataSource.supplementaryViewProvider = { collectionView, kind, indexPath in
guard kind == UICollectionView.elementKindSectionFooter else {
return nil
}
let section = dataSource.snapshot().sectionIdentifiers[indexPath.section]
guard let tabInfoSettingsFooterCell = collectionView.dequeueReusableSupplementaryView(
ofKind: kind,
withReuseIdentifier: TabInfoSettingsController.tabInfoSettingsFooterCellClassName,
for: indexPath) as? TabInfoSettingsFooterCell else {
return nil
}
tabInfoSettingsFooterCell.label.text = section.footer
//set tableSection value
self.tableSection = tabInfoSettingsFooterCell
return tabInfoSettingsFooterCell
}
return dataSource
}
TabInfoSettingsItemCellDelegate
func crossButtonClick(_ sender: UIButton) {
let hitPoint = (sender as AnyObject).convert(CGPoint.zero, to: collectionView)
if let indexPath = collectionView.indexPathForItem(at: hitPoint) {
footerValue = footerValue + 1
tabInfoSection.footer = String(footerValue)
//Update section value
self.tableSection?.label.text = String(footerValue)
}
}
With my system I build my cell programmatically and set what I need in the cell compared to my array (data source of my tableView).
The problem appear when I add 3 cells or more on my tableView. The text is good but the image does not appear in the correct cell. I think this is a problem of the cache of the TableView system (reuse). I follow several post in this forum to fix that but nothing work.
This is my code in cellForRowAt :
let waitingCell = tableView.dequeueReusableCell(withIdentifier:"waiting", for: indexPath) as! CardCellWaiting
var cellToReturn : UITableViewCell!
let currentSurvey = user.lobbySurvey[indexPath.row]
let state : UserSurvey.state = currentSurvey.stateSurvey
switch state{
case .surveyWaiting:
cellToReturn = waitingCell
waitingCell.drawCard() // draw the card programmatically if needed
waitingCell.clearImage() // look below to see the function
waitingCell.setId(id: currentSurvey.id)
waitingCell.setImage(image : currentSurvey.picture)
waitingCell.setTimeLeft(timeLeft: currentSurvey.timeLeft)
waitingCell.delegate = self
waitingCell.delegateCard = self
}
return cellToReturn
this is how I update my source data (lobbySurvey) an array who contain User Survey classes. I build my cells since this one.
user.lobbySurvey.remove(at: 0)
self.tableView.deleteRows(at: [IndexPath(row: 0, section: 0)], with: .fade)
let surveyWaiting = UserSurvey(stateOfSurvey: .surveyWaiting)
surveyWaiting.picture = image
if let url = json["imageUrl"].string {
surveyWaiting.pictureUrl = url
}
if let timeLeft = json["timeLeft"].string {
surveyWaiting.timeLeft = timeLeft
}
if let surveySelfId = json["surveySelfId"].string {
surveyWaiting.id = Int(surveySelfId)
}
let rowToInsert = self.getRowToInsert(typeOfState: .surveyWaiting)
user.counterSurvey += 1
user.lobbySurvey.insert(surveyWaiting, at: rowToInsert)
self.tableView.insertRows(at: [IndexPath(row: rowToInsert, section: 0)], with: .fade)
this is the clearImage function :
func clearImage(){
surveyWaiting.imageEmptyView.image = #imageLiteral(resourceName: "backgroundEmptyImage")
}
and my setImage function :
func setImage(image : UIImage){
surveyWaiting.imageEmptyView.image = image.resized(targetSize: CGSize(width:100,height:125))
}
I've try to empty my imageView like :
surveyWaiting.imageEmptyView.image = nil
But it doesn't work. I've also try to use a framework like Nuke with the url of the image, but nothing.
Why does my code not order the image in the good cell?
Ok, my mistake... I use this framework to draw async blur to my imageView, but this plugin keep cache of the image who have blur.. So I just remove the cache of the blur and this solve the problem.
I'm using firebase. My code works but my issue is when I press the accept button, I want that index to be deleted from the collectionView and I want the table to reload right away right after. I can't use the slide to delete because I need it for another function.
This is in my cell class thats why I did not use self. to call the collectionView. This function is being called by a addTarget() method. I'm thinking maybe passing an indexPath as a parameter, but I don't know how to pass an indexPath.item as a parameter and also how to pass a parameter inside an addTarget() method.
func handleAccept(_ sender: UIButton) {
print("button pressed")
guard let artId = art?.artId else {return}
let approvedRef =
FIRDatabase.database().reference().child("approved_art")
approvedRef.updateChildValues([artId: 1])
let pendingRef =
FIRDatabase.database().reference().child("pending_art").child("\(artId)")
pendingRef.removeValue { (error, ref) in
if error != nil {
return
}
let layout = UICollectionViewFlowLayout()
let pendingArtCollectionViewController =
PendingArtsCollectionViewController(collectionViewLayout: layout)
DispatchQueue.main.async {
pendingArtCollectionViewController.collectionView?.reloadData()
}
}
}
You don't need to pass indexpath as argument, you can get the indexpath of the tableView in button action with the following code :
func handleAccept(_ sender: UIButton) {
let center = sender.center
let rootViewPoint = sender.superview!!.convert(center!, to: self.myTableView)
let currentIndexpath = myTableView.indexPathForRow(at: rootViewPoint)
}
I'm really close to figuring this out. So in the iOS mail app when you click on the two arrow keys it takes you to the previous/next mail. Its on the top right
I've managed to pass the indexPath value to my second viewcontroller and print in in the console. I can also increase and decrease from it.
if segue.identifier == "DetailVC" {
let detailVC = segue.destination as! DetailVC
let indexPath = self.collectionViewIBO.indexPathsForSelectedItems?.last!
detailVC.index = indexPath
}
EDIT
This is where I'm pulling the data from. It reads the values from my model. I cannot assign an indexPath to it however. I can only do that from the previous view controller
var monster: Monsters!
I've attempted to implement the "previous" functionality using this code. My view styling are in the displayDataForIndexPath() function and the function is called from my view will appear
#IBAction func monsPreviousIBO(_ sender: Any) {
self.index = IndexPath(row: self.index.row - 1, section: self.index.section)
displayDataForIndexPath()
}
But all it does is decrease the IndexPath. For some reason the data doesn't actually reload with my function. I'm missing some important puzzle piece here to achieving the same functionality.
EDIT The code in my displayDataForIndex is as follows
func displayDataForIndexPath() {
if index.row == 0 {
self.monsPreviousIBO.removeFromSuperview()
}
var monsterName = (String(format: "%03d", monster.speciesId!))
self.navigationItem.title = monster.name!
let gif = UIImage(gifName: monsterName)
self.gifIBO.setGifImage(gif, manager: gifManager)
gifIBO.contentMode = .center
guard monster.legendary! != true else {
// Value requirements not met, do something
monsterStatusLegend()
return
}
guard monster.subLegend! != true else {
// Value requirements not met, do something
monsterStatusSub()
return
}
guard monster.isMega! != true else {
// Value requirements not met, do something
monsterStatusMega()
return
}
}
you display all data depending on monster but you never change the monster depending which indexPath you used.
add some code to populate the monster from indexPath
monster = getMonster(index.row)
or in your case
#IBAction func monsPreviousIBO(_ sender: Any) {
self.index = IndexPath(row: self.index.row - 1, section: self.index.section)
monster = mons[self.index.row]
displayDataForIndexPath()
}
or better in the displayDataForIndexPath() add this line:
func displayDataForIndexPath() {
if index.row == 0 {
self.monsPreviousIBO.removeFromSuperview()
}
monster = mons[self.index.row]
//....
NOTE some suggestions:
i would change the line for the button then it is enabled if the indexpath gets >0:
self.monsPreviousIBO.isEnabled = (index.row != 0)
just save the row as monsterIndex = indexPath.row and then deal only with the index and not indexPath.
you don't need to save the current monster as monster if you use the monster only in displayDataForIndexPath - then you can get the current monster just there and have it a local variable in this function:
var monster = mons[self.index.row]
I implemented an NSFetchedResultsController on a UITableView in a Core Data project in Swift 2.0. Additionally, I have a UISearchController implemented. Everything works perfectly with the exception of the behavior I'm encountering on my custom UITableViewCell buttons.
When UISearchController is active, the customTableViewCell's buttons work as they should. If I click the same button when the fetchedResultsController is displaying its results, the method thinks Index 0 is the sender, regardless of which button I click.
func playMP3File(sender: AnyObject) {
if resultsSearchController.active {
// ** THIS WORKS **
// get a hold of my song
// (self.filteredSounds is an Array)
let soundToPlay = self.filteredSounds[sender.tag]
// grab an attribute
let soundFilename = soundToPlay.soundFilename as String
// feed the attribute to an initializer of another class
mp3Player = MP3Player(fileName: soundFilename)
mp3Player.play()
} else {
// ** THIS ALWAYS GETS THE OBJECT AT INDEX 0 **
let soundToPlay = fetchedResultsController.objectAtIndexPath(NSIndexPath(forRow: sender.tag, inSection: (view.superview?.tag)!)) as! Sound
// OTHER THINGS I'VE TRIED
// let soundToPlay = fetchedResultsController.objectAtIndexPath(NSIndexPath(forRow: sender.indexPath.row, inSection: (view.superview?.tag)!)) as! Sound
// let soundToPlay: Sound = fetchedResultsController.objectAtIndexPath(NSIndexPath(index: sender.indexPath.row)) as! Sound
let soundFilename = soundToPlay.soundFilename as String
mp3Player = MP3Player(fileName: soundFilename)
mp3Player.play()
}
}
Here's an abbreviated version of my cellForRowAtIndexPath to show I'm setting up the cells' buttons:
let customCell: SoundTableViewCell = tableView.dequeueReusableCellWithIdentifier("customCell", forIndexPath: indexPath) as! SoundTableViewCell
if resultsSearchController.active {
let sound = soundArray[indexPath.row]
customCell.playButton.tag = indexPath.row
} else {
let sound = fetchedResultsController.objectAtIndexPath(indexPath) as! Sound
customCell.playButton.tag = indexPath.row
}
// add target actions for cells
customCell.playButton.addTarget(self, action: "playMP3file:", forControlEvents: UIControlEvents.TouchUpInside)
I've tried a few other approaches I've found here, such as translating CGPoints to IndexPaths, etc. without much luck. Everything that looked promising in the compiler crashed when I clicked the button in the simulator.
Thank you for reading.
Update
Installed Xcode 7.1, rebooted, cleaned caches, nuked derived data, did a cold boot.
Solution
Tags will get the job done in many cases (such as getting the location in an Array) and get lots of votes here, but as I've learned, they don't work all the time. Thank you to Mundi for pointing me towards a more robust solution.
// this gets the correct indexPath when resultsSearchController is not active
let button = sender as! UIButton
let view = button.superview
let cell = view?.superview as! SoundTableViewCell
let indexPath: NSIndexPath = self.tableView.indexPathForCell(cell)!
let soundToPlay = fetchedResultsController.objectAtIndexPath(indexPath) as! Sound
I've tried a few other approaches I've found here, such as translating CGPoints to IndexPaths, etc. without much luck.
Translating points is indeed the most robust solution. This answer contains the correct code.