I have an app that allows the user to create categories. A save screen appears with a UITextField. Although, I do not know how to save the user's entry, and allow a new UICollectionViewCell to be added into the current UICollectionView that contains the UITextField words that the user typed. Thanks!! This is also in Swift. This would be used in a UITableView: clothes.name = self.nameTextField.text ,but how would I convert this to a UICollectionView? **clothes is a variable
Your collection view has a data source where you initially have the model for your cells. In your case it's probably an array. The collection view looks at this data source and returns cells based on the entries contained in this data source.
What I am trying to get at is the following:
In order to show the newly created cell, you'll need to update your data source (I'll call it "the blueprint specification" the collection view adheres to) by adding the new cell's "specification" (I think I'm wording this in a more complex fashion than it actually is). Here is an example (If we assume that your data source is an array):
categoryArray.append(CategoryModel(title: yourTextField.text)) // update the data source
After you make changes to the data source you can tell the collection view to reload it's data:
collectionView.reloadData()
That will "parse" the data source to display the cells anew.
Let me know if anything is unclear.
EDIT
Regarding your comment -- given that you use a UINavigationController -- , you can achieve displaying the title like this:
You are probably using this method to go to your next view controller:
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
let category = categoriesArray[indexPath.row]
let detailVC = DetailViewController()
detailVC.title = category.title // your title
self.navigationController?.pushViewController(detailVC, animated: true, completion: nil)
}
Alternatively, in your DetailViewController you can do:
class DetailViewController : UIViewController{
var category : Category!
override func viewWillAppear(){
super.viewWillAppear()
self.title = self.category.title
}
}
Related
I've got a collection view with multiple cells created programically. I want to update a variable to a different value when the user taps a specific cell. So eg: Cell 1 is tapped -> var test = "cell1" , cell2 is tapped var test = "cell2". Usually I'd just create an IBAction by dragging from the storyboard but I'm not sure how to do it in this case.
I'm using Swift 3.1
To add interactivity to UITableViews, UICollectionViews, and other kinds of views which display collections of data, you can't use Storyboard actions, as the content is generated dynamically during runtime, and the Storyboard can only work for static content.
Instead, what you need to do is set your UICollectionView's delegate property to an object that implements the UICollectionViewDelegate protocol. One of the methods defined as part of the protocol is the collectionView(_:didSelectItemAt:) method. This method will get called whenever the user selects (taps) a collection view cell with the IndexPath to that cell as an argument. You can update your variable in that method. Just remember to deselect the cell after handling the tap by using the deselectItem(at:) method on your UICollectionView.
There are UICollectionView delegate that you need to implement. It goes like this
did select item at index path will give index path of the cell that was selected. Using indexpath or any other property of the data source array you are using, you can modify the variable value.
override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
if let cell = collectionView.cellForItemAtIndexPath(indexPath) {
//check your condition and modify the variable value depending on index path or any other property you are referring to.
}
}
I segued to a new View Controller. This view controller contains array data from the corresponding CollectionViewCell. How do I change the data to present the previous cell array? Without having to go back to the last view controller and selecting the cell from there? I'm using Swift 3 Below is an image that explains what I mean
The first image is in the first View Controller. The second and third images are what's displayed when either of the first two in the list are tapped. You can go to the next index using the arrow keys in the second View Controller. How do I achieve this functionality?
let dataSource = DataSource()
func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if inSearchMode {
return filteredAnimal.count
}
return dataSource.anim.filter{ $0.isDefault! }.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "AnimIndex", for: indexPath as IndexPath) as! AnimIndex
let animal: Animal
if inSearchMode {
animal = filteredAnimal[indexPath.row]
} else {
animal = dataSource.anim.filter{ $0.isDefault! }[indexPath.row]
}
cell.configureCell(animal)
return cell
}
This is a very common UI pattern. You should search on master/detail. You should be able to find lots of sample projects that give examples of this UI pattern.
Don't think in terms of cells. Think in terms of a model object - a store for your app data. You need a model object that represents the entire list of data you present in your first view controller.
That model object should be reachable from all view controllers that need to display information from it. You can either pass around a reference to the model object or make it a singleton. There are advantages to either approach.
For collection views and table views, which are organized by section and row, an array of arrays of data objects is often a good structure for your model. If your data is in a single section then you can use a single array.
When the user taps on a cell in your first view controller, you would invoke the second view controller (Either from a segue or by manually invoking it.) You'd pass the second view controller the indexPath of the selected object, and might also pass a reference to your model object (or, like I said, you could make the model object a globally accessable singleton, in which case you wouldn't need to pass it.)
Then, in the second (or 3rd) view controller, if the user taps the up/down button, you have access to the model object that stores ALL the data your app is presenting, so you can navigate to the next object from within any view controller. If your data is organzied in sections and rows or rows and columns you might want to add next/previous item methods to your data model so you only have to write that logic once.
I need an event, that changes a variable based on which TableViewCell I click. But unlike an action connected to a button, there is no action indicator for table view cells at all. So my question is:
I want to make a TableView that contains items of an array. Based on which item I click, I want to change my variable so that the result on the next ViewController depends on which button you click.
So to make things easier, here is an example what I want the app to look like:
On the first TableViewController I have a list based on an array and on the second ViewController I have a label that shows text based on the variable.
I have a nameArray = ["Mum", "Brother", "Me"] and a weightArray = [140, 160, 120] and a variable weight = 0. The label on the second ViewController tells the var weight. So when you click on "Mum" in the TableView I want the next ViewController to say 140, when I click on "Brother" then 160 and so on...
Until here everything works just fine and I have no problems with anything but changing the var based on what I click.
Long story, short sense:
I want an Action for the TableViewCell that changes the var like in an Action connected to a Button, but there is no Action outlet for Cells at all.
Use this method. Use indexPath.row to find what row number you selected
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
var cell : UITableViewCell = tableView.cellForRowAtIndexPath(indexPath)!
switch cell.labelSubView.text as! String {
case "Mum":
self.weight = weightArray[0]
case "Brother"
self.weight = weightArray[1]
and so on..
..
default:
statements
}
}
Note A better alternative
I also considered a case where you have too many entries in nameArray and switch statement might not be good. In that case you can get the text inside the selected row by cell.labelSubView.text as! String
next you can check if the nameArray contains the cell text and get the index of the name that matches the cell text. Next you can get the required weight at the same index in weightArray. And then do self.weight = weightArray[requiredIndex]
Hope this helps.
Update : My experienced friend #Duncan mentioned down below that switch statement in this case is a bad coding practice . I am not going to delete it because it is a lesson for me and also my fellow programmers who are relatively new to programming. So i have put it in a yellow box, stating that it is not a good code
A better option for this would be :
As Duncan mentions, creating an array of dictionary is a good option
Second option is the option in my answer after my Note
You need to maintain array of dictionaries , those dictionaries have keys like "person", and "weight", then you can easily get weight value after selecting the cell by using table view delegate method UITableViewDelegate's tableView:didSelectRowAtIndexPath:
Create an instance variable in your view controller (a var at the top level after the class definition) for the selected cell.
class MyTableViewController: UIViewController
var selectedRow: Int
override func tableView(tableView: UITableView,
didSelectRowAtIndexPath indexPath: NSIndexPath)
{
selectedRow = indexPath.row
//invoke a segue if desired
performSegueWithIdentifier("someSegue");
}
override func prepareForSegue(segue: UIStoryboardSegue,
sender: AnyObject?)
{
if segue.identifier == "someSegue"
{
//Cast the destination view controller to the appropriate class
let destVC = DestVCClass(segue.destinationViewController)
destVC.selectedRow = selectedRow
}
}
As Andey says in his answer, it's probably better to create a single array of data objects (dictionaries, structs, or custom data objects). Then when the user taps a cell, instead of passing the index of the selected row to the next view controller, you could pass the whole data object to the destination view controller. Then the destination view controller could extract whatever data it needed. (Weight, in your example.)
I am displaying data in a collection view, I know how to pass the data on with prepareForSegue function but am trying to have the app determine which segue to use depending on the cell property data. (Each segue goes to a different view controller to display relevant information.)
For e.g.
If the cell.type is equal to "1" then perform segueOne if it is of type "2" then perform segueTwo.
I was trying to do something like this;
func collectionView(collectionView: UICollectionView, shouldSelectItemAtIndexPath indexPath: NSIndexPath) -> Bool {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! CollectionViewCell
if cell[indexPath].type = "1" {
performSegueWithIdentifier("showPage1", sender: self)
} else if self.cell[indexPath].type = "2" {
performSegueWithIdentifier("showPage2", sender: self)
} else { println("error when selecting cell to segue") }
}
However with this I get an error;
'CollectionViewCell' does not have a member named Subscript
Has anybody got any ideas ?
Assuming the items in your collection view can be re-arranged (or might be some time in the future), the indexPath will not be sufficient to give you the information which cell was selected. Thus, IMO your idea to give the cell a property is a feasible one.
The easiest "quick and dirty" way is to simply hardcode the segue identifier string into your cell. This is not the best design because you are introducing dependencies between app elements that should know of each other.
class MyCell : UICollectionViewCell {
var segue = "DefaultSegue"
}
Now calling the appropriate segue is really easy in didSelectItemAtIndexPath...
self.performSegueWithIdentifier(cell.segue, sender:cell)
It would of course be preferable to use an enum. Safer, more readable and better maintainable.
enum Segue : String {
case ToInfo = "SegueToInfo"
case ToLogin = "SegueToLogin"
// etc.
}
The ivar for MyCell would now be var : Segue = SomeDefaultValue and you can call it the same way.
BTW: Regarding your original question please note the following: as has been pointed out, you cannot subscript a cell. (UICollectionViewCell is not a Dictionary, so cell["key"] does not make sense.) Also, I am not a fan of dequeueing the cell in more than one place - instead you could call cellForItemAtIndexPath or do the work in that method in the first place, as I have suggested.
You're trying to index into a UICollectionViewCell, but of course that class is not an array, so you can't 'subscript' it.
My suggestion is to refactor your code. Whatever data you're storing in your cell you can presumably get from your data model, because that's where it originally came from. You are probably putting that in your cell in cellForIndexPath.
If that is the case, then there is no reason you can't get the same data from the same place in your func ... shouldSelectItemAtIndexPath ... -> Bool. I'd suggest doing it there. Your cell should only contain the data it needs to properly render itself to the screen.
See if that helps.
I have a UITableViewController and when I click on it, it will show a DetailViewUIController.
I want to add a functionality which when I am in DetailViewUIController and I swipe to right, it will show the DetailViewUIController of next item and when left, it will show the previous item.
I find a link which kind of do that in swift. But it only has 3 static subviewcontroller.
https://medium.com/swift-programming/ios-swipe-view-with-swift-44fa83a2e078
The number of entries in my TableView can be pretty long, how can I do the same thing dynamically, i.e. without having static number of subviewcontroller created and add as 'addChildViewController'?
Update:
Thanks again #rdelmar for your help.
I am having trouble getting the ' set the contentOffset of the collection view to (collection view width) * selectedRow' to work.
In my prepareForSegue function, I have added:
x = Float(indexPath.row) * 375.0
var point = CGPointMake(CGFloat(x), 0)
println ("***x=")
println (x)
detailController.collectionView?.setContentOffset(point , animated: false)
where detailController is UICollectionViewController.
and in the
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as DetailViewCell
// Configure the cell
println("DetailViewController in cellForItemAtIndexPath()")
println(indexPath.row)
cell.myitem = allItems[indexPath.row]
return cell
}
And I always see cellForItemAtIndexPath trying to get 0th element of the allItems (that is the whole collections of all my objects.
So setContentOffset() does not change what I am displaying in the Detail View regardless which item I click in my TableView to launch the Detail View.
Any idea to solve this?
Thank you.
There are a lot of different ways you could do this. One way would be to make your detail view controller's view be a collection view (with paging enabled), whose cells are the same size as the screen. You would need to pass in the array that you use to populate your table so the collection view could populate its cells. This would be quite efficient, since the collection view would only ever need to instantiate two cells.