I've been wrestling for hours with the following problem: I have an image in each of my cells of a UITableView which I'd like to toggle when tapped. Currently, in the function where I establish the cells,
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath)
I have the following code which attaches the UIGestureRecognizer to the image in each cell:
cell.imageView!.userInteractionEnabled = true
cell.imageView!.tag = indexPath.row
var tapped:UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "TappedImage:")
tapped.numberOfTapsRequired = 1
cell.imageView!.addGestureRecognizer(tapped)
Currently, I am trying to figure out how to change that cell's image in:
func TappedImage(sender:UITapGestureRecognizer)
It seems that I am able to change the background for the image, or set it to hidden, for example, but not actually change it. Maybe this is a question of accessing the cell? I've been trying to figure out how I would define it in this function from the imageView tag, but I also have sections, which I think may make the tag less relevant (as I would need to reference both section and row). I have the toggle function written which passes in a cell which I could easily call from this function if I can access the exact cell. Any advice or sample code is much appreciated. Thank you for reading.
Thank you
Related
I’m coding a “chatbot” app, and to hold the message bubbles I have a UITableView and a custom message-bubble shaped cell. Here’s what it looks like so far:
All the cells will look the same, except I’d like every other cell to be, say, half the width of the table and alternating right/left aligned. How could I do this programmatically?
The better way - to create two classes InMessageCell, OutMessageCell, and add all properties (like aligning of all elements) hide inside of this cell. Both cell will have the same width, but all bubbles will be moved on one or other side. It may inheritance from the main class MessageCell, so all logic may stay in main class, but UI part - splitted up.
Two straightforward ways of achieving this by using custom table view cells:
Have two different cell classes. They can share much of their implementation (e.g. by class heritage), but differ in their layout (one is left aligned, one right aligned). For each row in your table, decide which cell you need to use, and dequeue the appropriate one.
Have one cell class whose layout can be toggled when it's being dequeued. (How exactly this toggle looks like depends of course on how you chose to layout your cell. It could e.g. be that you exchange the constant to an autolayout constraint you reference via #IBOutlet, the switching of a background image, or changing the alignment property of a stack view, among many others.)
Both ways depend on making a decision which cell flavor to use in your UITableViewDataSource's tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) function.
Here is a slightly abstract example using the first method. In your UITableViewDataSource:
enum ChatCellAlignment {
case left
case right
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cellAlignment: ChatCellAlignment = self.cellAlignmentForIndexPath(indexPath) // you need to implement something like this
var identifier = "Default"
switch cellAlignment {
case .left:
identifier = "LeftAlignedBubbleCell"
case .right:
identifier = "RightAlignedBubbleCell"
}
let cell = self.tableView.dequeueReusableCell(withIdentifier: identifier)
if let cell = cell as? ChatBubbleCell { // assuming your custom cell classes all inherit from a "ChatBubbleCell"
cell.set(text: self.textForIndexPath(indexPath))
... // whatever setup you need to do on your custom cell
}
return cell
}
You can give the table view cell a value to know it. Then you can use autolayout (SnapKit) to make it align left or right
I have created a single prototype cell which has two labels (mainLabel and subLabel) and an uiimageview. In the uitableview I'd like to have several cells which reuse the prototype and when needed the subLabel is hidden and the uiimageview is changed with different one or with a uiswitch. The two labels have different text for each cell. Do you have any suggestions/hints in order to do it? possibly in a mvvm architecture?
I'll describe what I am doing:
I have a struct (the Model) with two properties: label and sublabel. This is then instantiate by a viewModel which provides text for each cell, done by a method called getModel(_ indexPath: IndexPath) -> cellModel { ... }. Finally in UIViewController, in tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) { ... } I am calling getModel(), using dequeueReusableCell and setting up each cell.
In getModel() there is a huuuuge switch which I use to know which cell is which
Then in uitableviewcell I have some method that hides sublabel and changes uiimageview.
It kind of works, however I have some issues with while scrolling. For example, sometimes a uiimageview is drawn in another cell, or a subLabel is hidden, even if it is not supposed to. I guess this is due because it is reusing the cell, and I am not resetting it.
Anyway, any suggestions or ideas?
I know this is overkilling...
No need for any pattern. Yes, you can use that single cell design for all cells. Just hide/empty label(s) and image view as you like per cell.
First of all you have to set default value to both the labels and imageview
i.e. (consider a title label, a sub label and a imageview)
lblTitle.isHidden = false
lblSubLabel.isHidden = false
imgViewIcon.image = nil
Then just show labels in specific condition that you want to match and set image in imageview
i.e. (consider your condition to hide sub label)
if needToHide == true {
lblSubLabel.isHidden = true
}
I am trying to have two buttons as the first row and the rest of the rows as it is shown in the following picture (I apologize for the flipped picture):
I know how to put two buttons in a cell, like so:
And use the following code to add the first cell to my tableview like so:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
if indexPath.row == 0 {
//Configure the first cell with the two buttons
} else {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath)
cell.textLabel?.text = cathyList[indexPath.row]
}
return cell
}
My logic allows me to have two buttons as the first row cell but I don't know how to make the buttons big and square like the ones that are shown here. Any suggestions?
You format your button as what you want on Storyboard. I suggest 2 options you can get this:
You can add image and title on button and use Edge property to achieve this. Look at this:
This way is hard to achieve what you need, you have to make sure your icon has the right size, and it's not dynamic.
The second way is easier and more dynamic. But maybe not the best solution. I usually use this way.
You add an image (show your icon), a label (your title) and embed them in a view. Then add a button stretch all the view. Connect this button to action and use it as usual.
Hope this help.
Bit of a weird one i can't seem to understand so i have a tableview control in a viewcontroller and within the tableviewcell i have a button which is using a delegate.
So when the button is clicked it will change the tag number of the cell and also change the image of the button based on the tag of the cell in the tableview.
But the problem i'm having is that when you select a button in a row i.e. the first one it seems to be running the function to change the image for each item in a section almost. I.e choosing the 5th item will update every 5th button in a cell to the selected image which is weird. Since it's almost like the tableview is being split up to sections of 5.
Can anyone help prevent this behaviour so it only changes the icon for the button in the cell which has been pressed.
Below are the functions that i've used and a link to a video on dropbox showing the behaviour https://www.dropbox.com/s/a4aasti78872w6j/Help.mov?dl=0
Delegate
protocol StoryTableViewCellDelegate: class {
func didBookmarkItem(cell: StoryTableViewCell, sender: AnyObject)
}
Function for Delegate
#IBAction func bookmarkButtonDidTouch(sender: AnyObject) {
bookmarkButton.animation = "pop"
bookmarkButton.curve = "easeOut"
bookmarkButton.duration = 0.5
bookmarkButton.damping = 0.4
bookmarkButton.velocity = 0.4
bookmarkButton.animate()
// The delegate which will handle bookmarking items
delegate?.didBookmarkItem(self, sender: sender)
}
Function being used in tableview class
// MARK: StoryTableViewDelegate
func didBookmarkItem(cell: StoryTableViewCell, sender: AnyObject) {
// TODO: Implement bookmark functionality
switch cell.bookmarkButton.tag {
case 0:
cell.bookmarkButton.setImage(UIImage(named: "Bookmark-Selected"), forState: UIControlState.Normal)
cell.bookmarkButton.tag = 1
case 1:
cell.bookmarkButton.setImage(UIImage(named: "Bookmark-Not-Selected"), forState: UIControlState.Normal)
cell.bookmarkButton.tag = 0
default:
break
}
}
The reason is, you are probable creating a cell using :
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cellID")
...
like you should do. However dequeueReusableCellWithIdentifier re-uses a cell, so if you have changed anything in a cell (like adding buttons), those buttons will still be in that recycled cell.
So you must set the book mark status in your cellForRowAtIndexPath for each cell.
I once had a similar problem when adding buttons to a cell, and when scrolling the cells automatically had extra buttons. So the first thing I did when re-using a cell was remove all buttons.
Edit sample code
in your
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath)
you have to add code for setting the button to the desired state, it will be something similar to the code you're using in didBookMarkItem :
switch myProperty {
case 0:
cell.bookmarkButton.setImage(UIImage(named: "Bookmark-Selected"), forState: UIControlState.Normal)
cell.bookmarkButton.tag = 1
case 1:
cell.bookmarkButton.setImage(UIImage(named: "Bookmark-Not-Selected"), forState: UIControlState.Normal)
cell.bookmarkButton.tag = 0
default:
break
}
You'll need a myProperty variable of course, which you should change in your didBookMarkItem as well
As others have said, it's due to table cell reuse. You want your tableView(_:cellForRowAtIndexPath:) method to always update the cell state from your model. Your bookmark state should be a property of your model. When the bookmark button state for a cell is changed by the user, the new state should be reflected in your model. If you do these things, your table cell state will always be correct. If you don't already, it's nice to always define a custom UITableViewCell class that contains outlets for all of the views and controls within your table view cell (your bookmark button would have an outlet.) Also, within your custom cell class, when you capture the button selection, you can call back to the controller either via a delegate (as you are doing), or a "bookmarkChanged" handler (closure) defined on the cell. I prefer the closure method. If you would like to see an working example of this, let me know.
Also, nix the tag. You don't need the tag to keep track of your bookmark button selection state, unless there's more to it than you have shown/described. If you follow the approach I described, it's taken care of.
Table view cells are reused. Once you select a cell and change its tag number and scroll the selected cell out of the table view, it will be used again to show a row at the index path of the new row that appears. And since its tag represents that of a selected cell it is displayed as highlighted.
Try to look up about cell reuse in table views.
You need to change your approach about determining which cell is to be displayed as selected. Add it as a property in your data source and based on that set the bookmark as selected or not selected.
I'm trying to do the opposite of what most people on this topic are asking to do. Most people want a button within a table view cell to call a method in their VC / VC table. I already have a protocol doing that.
Problem / Question
What I am trying to add now is the opposite: I need a button press on my main ViewController (which houses my table) to call a method within my CusomTableViewCell class (note: the button pressed on the main VC is not in the table). I have the protocol class created and the function written, but I don't know how to set the CustomCellViewClass as the delegate. When I did the opposite, I inserted "cell.delegate = self" into the cellForRowAtIndexPath method. I've also used prepareForSegue to assign a delegate. But with no segue and now cell-creation-method, I'm lost!
Example of Desired Function
My end goal is that pressing a button that is in the main VC will change the title of a button within the cells. A simple example would be that I have one view with a single table, on button press the table contents switch between two arrays, cars and motorcycles. When the table is showing cars, the cell button titles should all read "Look inside" but when showing the motorcycle button it should read "Look closer".
Code
I've already written the function that I want the cell to execute:
func cellButton_Title_Switch (currentList: String) {
if vcState == "cars" {
cellButton.setTitle("Look inside", forState: UIControlState.Normal)
}
else {
cellButton.setTitle("Look closer", forState: UIControlState.Normal)
}
}
I created the protocol:
protocol delegateToChangeCellBut {
func cellButton_Title_Switch (currentList: String)
}
I have the self.delegate.cellButton_Title_Switch(currentList) within my VC button and the protocol added to my custom cell class declaration. But how do I do that last missing piece in the custom cell class, where I assign the class to the delegate?
My original problem was that my UITableView's cell has buttons and labels, some of which change to match the state of things outside the table, things handled by the mainViewController.
The custom cell is defined by a customCellviewController. All the custom cell buttons and labels have their IBOutlets connected to the customCellviewController. I couldn't figure out how to make an action/change outside the table (in the mainViewController) immediately cause the cell labels and buttons to change.
Note: Protocols tend to work they other way around (a cell action triggers a function in the mainVC). I couldn't figure out how to use a protocol to solve this. Luckily, the solution was much simpler than a protocol.
The Solution!
I wrote the "updateCell" method that would change the labels and buttons and that code now sits in the customCellviewController. Then I called/triggered the "updateCell" function from the mainViewController simply by adding the call into my cellForRowAtIndexPath function. So it looks something like this:
var stateOfPage = "Green"
//Creates the individual cells. If the above function returns 3, this runs 3 times
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
//Setup variables
let cellIdentifier = "BasicCell"
let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! customCell
cell.updateCell(stateOfPage)
return cell
}
Now the above code/method runs when the table gets built. So to update the cells, have some button tap or other action reload the table data:
tableView.reloadData()
Good luck.