Swift: Change button image in table view on click - ios

Question

I created an Xcode project for iPhone using Swift, with Parse for the backend. My current problem is with creating a todo list application as one tab of a larger application.
Inside of a custom prototype cell, I want to have a checkbox button that changes its image when clicked as well as changing the isChecked:Bool variable for that cell. I've gotten most of the way there, but I've run into a brick wall regarding setting and accessing the appropriate variables for this button.
Edit: Thanks to the answer below and other resources, I have finally written working code for this checkbox functionality. Essentially, the button's tag property is set equal to the indexPath.row of the PFObject. As my original question was a bit broad, I am updating my code below so that it might help other new developers who are working on similar functionality. There may be better ways, but this seems to work.
// TasksVC.swift
var taskObjects:NSMutableArray! = NSMutableArray()
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
self.fetchAllObjects()
}
func fetchAllObjects() {
var query:PFQuery = PFQuery(className: "Task")
query.whereKey("username", equalTo: PFUser.currentUser()!)
query.orderByAscending("dueDate")
query.addAscendingOrder("desc")
//fetches values within pointer object
query.includeKey("deal")
query.findObjectsInBackgroundWithBlock { (tasks: [AnyObject]!, error:NSError!) -> Void in
if (error == nil) {
var temp:NSArray = tasks! as NSArray
self.taskObjects = temp.mutableCopy() as NSMutableArray
self.tableView.reloadData()
println("Fetched objects from server")
} else {
println(error?.userInfo)
}
}
}
//MARK: - Tasks table view
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.taskObjects.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = self.tableView.dequeueReusableCellWithIdentifier("TaskCell", forIndexPath: indexPath) as TaskCell
var dateFormatter:NSDateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "M/dd/yy"
var task:PFObject = self.taskObjects.objectAtIndex(indexPath.row) as PFObject
cell.desc_Lbl?.text = task["desc"] as? String
cell.date_Lbl.text = dateFormatter.stringFromDate(task["dueDate"] as NSDate)
//value of client within Deal pointer object
if let deal = task["deal"] as? PFObject {
// deal column has data
if let client = deal["client"] as? String {
// client has data
cell.client_Lbl?.text = client
}
}
//set the tag for the cell's UIButton equal to the indexPath of the cell
cell.checkbox_Btn.tag = indexPath.row
cell.checkbox_Btn.addTarget(self, action: "checkCheckbox:", forControlEvents: UIControlEvents.TouchUpInside)
cell.checkbox_Btn.selected = task["isCompleted"] as Bool
if (task["isCompleted"] != nil) {
cell.checkbox_Btn.setBackgroundImage(UIImage(named:(cell.checkbox_Btn.selected ? "CheckedCheckbox" : "UncheckedCheckbox")), forState:UIControlState.Normal)
}
cell.selectionStyle = .None
return cell
}
func checkCheckbox(sender:UIButton!) {
var senderBtn:UIButton = sender as UIButton
println("current row: \(senderBtn.tag)")
//retrieve the PFObject for the row we have selected
var task:PFObject = self.taskObjects.objectAtIndex(senderBtn.tag) as PFObject
println("objectID: \(task.objectId)")
if task["isCompleted"] as NSObject == true {
task["isCompleted"] = false
} else {
task["isCompleted"] = true
}
task.saveInBackgroundWithBlock { (success, error) -> Void in
if (error == nil) {
println("saved checkbox object in background")
} else {
println(error!.userInfo)
}
}
self.tableView.reloadData()
}
override func tableView(tableView: UITableView?, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
return true
}
override func tableView(tableView: UITableView?, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
if (editingStyle == UITableViewCellEditingStyle.Delete) {
var task:PFObject = self.taskObjects.objectAtIndex(indexPath.row) as PFObject
task.deleteInBackgroundWithBlock({ (success, error) -> Void in
self.fetchAllObjects()
self.taskObjects.removeObjectAtIndex(indexPath.row)
})
} else if editingStyle == .Insert {
}
}

Answer 1

When working with tables and collection views, all the objects you have in a custom cell can be easily accessed in cellForRowAtIndexPath (for UITables)
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCellWithIdentifier("ActionCell", forIndexPath: indexPath) as ActionCell
var action = actions[indexPath.row] as Action
cell.nameLabel?.text = action.name
cell.listLabel?.text = action.list
cell.dateLabel?.text = action.date
cell.checkboxButton = action.isChecked
cell.checkBoxButton.setImage(UIImage(named:"checkedImage"), forState:UIControlState.Normal)
return cell
}
more over I would suggest to change constants to variables. I'm new to Swift too and "let" declares a static variable.
I find very cool the use of the conditional operator (?:) in these cases:
cell.checkBoxButton.setImage(UIImage(named:(any_boolean_condition ? "checkedImage" : "uncheckedImage")), forState:UIControlState.Normal)
so it can return one image name for the condition True and another name for the condition False.