I've an application that works with a static cells table view. In some cases in need to hide a few cells and when needed show them again. How can i do this ?
To do what you wanna do I work with numberOfRowsInSection tableview's method using a bool variabile
if section == 3 {
if !hideTableSection! { return 1 } else { return 2 }
}
Every time I need to hide some cell I change the bool variable then I reload my table.
It can manage only the latest rows of every section but I didn't find nothing better...
Related
It can sounds weird but I don't understand why my tableView is showing cells.
I got array of items that should be shown in cells but I don't run reloadData method of my tableView anywhere in my code. It seems that some of app components or maybe frameworks inside app is calling reloadData method and I want to find out which one?
How it can be done?
A table view loads itself the first time it is added to the window hierarchy. You don't need an explicit call to reloadData for the table to load itself initially.
If you want to see how this is really done, put a breakpoint on your table view data source methods and bring up your table view. Look at the stack trace in the debugger to see the sequence of events.
If your data preparation takes some time and you do not want the table view to show any data initially you could use an approach like this:
class TableViewController: UITableViewController {
var someDataSource: [Any]!
var dataSourcePrepared = false {
didSet {
tableView.reloadData()
}
}
override func numberOfSections(in tableView: UITableView) -> Int {
guard dataSourcePrepared else { return 0 }
return someDataSource.count
}
func doSomePreparationStuff() {
// ...
// ...
someDataSource = ["Some", "Content"]
dataSourcePrepared = true
}
}
In this case I used a Bool variable dataSourcePrepared which is false initially. As soon as you have prepared your content set it to true and the table view gets reloaded.
I have a collection view with three different cells. Each of the cells contains a table view. So, there are three table views. I've set tags for each of them (from 1 to 3).
Now, on my view controller (I set it as the table view's data source when I dequeue collection view's cells) I call table view's data source method for the number of rows. To distinguish table views I check each one's tag. Here is the code for that:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
switch tableView.tag {
case 1:
if unitItems1 != nil {
return unitItems1!.count
} else {
return 0
}
case 2:
if unitItems2 != nil {
return unitItems2!.count
} else {
return 4
}
case 3:
if unitItems3 != nil {
return unitItems3!.count
} else {
return 4
}
default:
return 0
}
}
The problem is, when the first cell of the collection view is shown (with the first table view) it works fine. But when I scroll to the second cell, BOTH case 2 and case 3 get executed. After that, the second table view shows data as expected, but when I scroll to the third one, the method doesn't get called.
I can't figure out why two case statements get called one after another, while everything works fine for the first cell. If you have any ideas why this happens (or maybe, you could suggested a better way of checking table view's), I would appreciate your help.
Actually, the solution is quite simple. The reason of the problem was that collectionView's data source method was dequeueing all the cells one after another, even when they weren't on the screen. Consequently, tableView's inside of each cell were getting set, too. So, their data source method was getting called, hence the problem.
UICollectionView has a property called isPrefetchingEnabled. According to the documentation it denotes whether cells and data prefetching is enabled.
The documentation says:
When true, the collection view requests cells in advance of when they will be displayed, spreading the rendering over multiple layout passes. When false, the cells are requested as they are needed for display, often with multiple cells being requested in the same render loop. Setting this property to false also disables data prefetching. The default value of this property is true.
So, to solve the problem, described in the question, I set it to false as soon as my collectionView gets set.
I have a HRMS screen containing many buttons. I want to categorise each button based on a more its functionality like
Attendance->
Attendance Marking
Attendance register
Leave->
Leave Request
Leave OD Authorise
Leave OD Approve
Others->
HolidayList
Leave Balance
Right now my screen look like this
I am trying to implement the expandable list view. The logic is simple that when clicking a sub menu I want to go to the specific View controller associated with it. Although I know how to do this using simple table view using
func tableView(tableView: UITableView!, didSelectRowAtIndexPath
indexPath: NSIndexPath!)
I cant figure out how to implement it while using the expandable table view. I googled about the same but couldn't get a specific solution.
You can use
func tableView(tableView: UITableView!, didSelectRowAtIndexPath indexPath: NSIndexPath!)
{
if (indexPath.section == 0)
{
if (indexPath.row == 0)
{
/*The first row of the first section was tapped.
Put code here that you would like to execute when the
first row of the first section is tapped*/
}
if (indexPath.row == 1)
{
/*The second row of the first section was tapped.
Put code here that you would like to execute when the
second row of the first section is tapped*/
}
}
if (indexPath.section == 1)
{
if (indexPath.row == 0)
{
/*The first row of the second section was tapped.
Put code here that you would like to execute when the
first row of the second section is tapped*/
}
if (indexPath.row == 1)
{
/*The second row of the second section was tapped.
Put code here that you would like to execute when the
second row of the second section is tapped*/
}
}
}
with expandable tableView same as with normal tableviews. Just put your code to call new viewController in the above method for the required tableView row.
One thing to keep in mind is that when you are using multiple sections (which your would be if you are using expandable tableView) then the indexing for the rows for each section starts from zero.
For example there are three sections in your tableView with three rows each, their indexing would be like this
Section 0
Row 0
Row 1
Row 2
Section 1
Row 0
Row 1
Row 2
Section 2
Row 0
Row 1
Row 2
So you need to check for both the section and the row in the didSelectRowAtIndexPath method
This question already has answers here:
How to detect the end of loading of UITableView
(22 answers)
Closed 6 years ago.
I need to call a function after the UITableView has been loaded completely. I know that in most cases not every row is displayed when you load the view for the first time, but in my case, it does as I only have 8 rows in total.
The annoying part is that the called function needs to access some of the tableView data, therefore, I cannot call it before the table has been loaded completely otherwise I'll get a bunch of errors.
Calling my function in the viewDidAppear hurts the user Experience as this function changes the UI. Putting it in the viewWillAppear screws up the execution (and I have no idea why) and putting it in the viewDidLayoutSubviews works really well but as it's getting called every time the layout changes I'm afraid of some bugs that could occur while it reloads the tableView.
I've found very little help about this topic. Tried few things I found here but it didn't work unfortunately as it seems a little bit outdated. The possible duplicate post's solution doesn't work and I tried it before posting here.
Any help is appreciated! Thanks.
Edit: I'm populating my tableView with some data and I have no problems with that. I got 2 sections and in each 4 rows. By default the user only sees 5 rows (4 in the first section, and only one in the second the rest is hidden). When the user clicks on the first row of the first section it displays the first row of the second section. When he clicks on the second row of the first section it displays two rows of the second section, and so on. If the user then clicks on the first row of the first section again, only one cell in the second section is displayed. He can then save his choice.
At the same time, the system changes the color of the selected row in the first section so the users know what to do.
Part of my issue here is that I want to update the Model in my database. If the users want to modify the record then I need to associate the value stored in my database with the ViewController. So for example, if he picked up the option 2 back then, I need to make sure the second row in the first section has a different color, and that two rows in the second sections are displayed when he tries to access the view.
Here's some code :
func setNonSelectedCellColor(indexPath: NSIndexPath) {
let currentCell = tableView.cellForRowAtIndexPath(indexPath)
currentCell?.textLabel?.textColor = UIColor.tintColor()
for var nbr = 0; nbr <= 3; nbr++ {
let aCell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: nbr, inSection: 0))
let aCellIndexPath = tableView.indexPathForCell(aCell!)
if aCellIndexPath?.row != indexPath.row {
aCell?.textLabel?.textColor = UIColor.blackColor()
}
}
}
func hideAndDisplayPriseCell(numberToDisplay: Int, hideStartIndex: Int) {
for var x = 1; x < numberToDisplay; x++ {
let priseCell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: x, inSection: 1))
priseCell?.hidden = false
}
if hideStartIndex != 0 {
for var y = hideStartIndex; y <= 3; y++ {
let yCell = tableView.cellForRowAtIndexPath(NSIndexPath(forRow: y, inSection: 1))
yCell?.hidden = true
}
}
}
These two functions are getting called every time the user touches a row :
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
let path = (indexPath.section, indexPath.row)
switch path {
case(0,0):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(1, hideStartIndex: 1)
data["frequencyType"] = Medecine.Frequency.OneTime.rawValue
case(0,1):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(2, hideStartIndex: 2)
data["frequencyType"] = Medecine.Frequency.TwoTime.rawValue
case(0,2):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(3, hideStartIndex: 3)
data["frequencyType"] = Medecine.Frequency.ThreeTime.rawValue
case(0,3):
setNonSelectedCellColor(indexPath)
hideAndDisplayPriseCell(4, hideStartIndex: 0)
data["frequencyType"] = Medecine.Frequency.FourTime.rawValue
default:break
}
}
I store the values in a dictionary so I can tackle validation when he saves.
I'd like the first two functions to be called right after my tableView has finished loading. For example, I can't ask the data source to show/hide 1 or more rows when I initialize the first row because those are not created yet.
As I said this works almost as intended if those functions are called in the viewDidAppear because it doesn't select the row immediately nor does it show the appropriate number of rows in the second sections as soon as possible. I have to wait for 1-2s before it does.
If you have the data already that is used to populate the tableView then can't you use that data itself in the function? I am presuming that the data is in the form of an array of objects which you are displaying in the table view. So you already have access to that data and could use it in the function.
But if that's not the case then and if your table view has only 8 rows then you can try implementing this function and inside that check the indexPath.row == 7 (8th row which is the last one).
tableView(tableView: UITableView, didEndDisplayingCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath)
Since all your rows are visible in one screen itself without scrolling you could use this function to determine that all the cells have been loaded and then call your function.
I've got a table view showing the output of a search. When I update it to show the output of a totally different search if the old set of results was longer then old cells remain below my new ones.
For examples, if my first results are:
[Sam,
Joe,
Sally,
Betty,
Bob]
then I have five cells, one per result, as expected. If my second set of results is short, say just
[Smith]
then I now have five cells (Smith, Joe, Sally, Betty and Bob), when only one (Smith) is expected.
Here's how I'm reloading:
results = getResults()
tableView.reloadData()
And here's how I'm getting the number of cells:
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if results != nil {
println("Table has \(results!.count) rows.")
return results!.count
}
println("Table is empty.")
return 0
}
which is printing out "Table has 1 rows." as expected, but the four old rows are still there.
Now, I could delete them before reloading, or delete the whole section, but is there a better way of achieving this? I thought reloadData would reload everything.
Additional Info
Here's cellForRowAtIndexPath as requested:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("SearchEventsCell", forIndexPath: indexPath) as SearchEventsCell
if results != nil && eventStore != nil && results!.count >= indexPath.row {
let event = results![indexPath.row] as EKEvent
cell.configureCellWithEvent(event)
}
else {
println("Couldn't dequeue the cell")
}
return cell
}
And just to prove we have the right number of rows I put a println in before reloadData():
println("We're about to reload the table view, we have \(numberOfSectionsInTableView(tableView)) sections and \(tableView(tableView, numberOfRowsInSection:0)) rows in section 0")
tableView.reloadData()
Which outputs
Table has 1 rows.
We're about to reload the table view, we have 1 sections and 1 rows in sections 0
Table has 1 rows.
as it should.
Something else I've noticed, which surely has to be related - the table doesn't update at all until I try scrolling. What am I missing? I know reloadData has been called as println is being called within numberOfRowsInSection.
Update
The textFieldShouldReturn method that triggers the update includes this code:
eventStore.requestAccessToEntityType(EKEntityTypeEvent,
{ accessGranted, error in
if accessGranted {
if let searchEventsController = self.searchEventsController {
searchEventsController.search(self.searchTextField.text)
}
}
else {
self.accessDenied()
}
}
)
which seems very likely to be the culprit. Is there a better way of checking for permission? I included it there so that if the user ever disallowed it it would ask again next time they try to use it, rather than just failing.
The problem was indeed the fact that reloadData was taking place in another thread due to the eventStore.requestAccessToEntityType call.
There are two solutions:
1) Perform the permissions check once, when the app loads, instead of every time you access the the EventStore, as suggested by Paulw11. This means for the majority of the application there's only one thread.
2) Use the following code to execute reloadData on the main thread:
dispatch_async(dispatch_get_main_queue()) {
self.tableView.reloadData()
}
as suggested by almas.
Update: I've just checked and if you revoke the permission for the app to access the Calendar then it doesn't ask the user again anyway, it just denies access, so there's no reason to keep the eventStore.requestAccessToEntityType where it is.