I'm using Xcode 6.0.1, iOS8 and Swift.
I have to reproduce in my UITableView
the same behavior of the Auto-Lock option in Settings->General. In Objective-C, in the past, I wrote
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CheckMarkCellIdentifier = @"CheckMarkCellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: CheckMarkCellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CheckMarkCellIdentifier] autorelease];
}
cell.textLabel.text = ...
cell.detailTextLabel.text = ...;
cell.accessoryType = [indexPath isEqual: self.lastSelectedIndexPath] ? UITableViewCellAccessoryCheckmark : UITableViewCellAccessoryNone;
return cell;
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
int newRow = indexPath.row;
int oldRow = self.lastSelectedIndexPath.row;
if (newRow != oldRow) {
UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];
newCell.accessoryType = UITableViewCellAccessoryCheckmark;
UITableViewCell *oldCell = [tableView cellForRowAtIndexPath:self.lastSelectedIndexPath];
oldCell.accessoryType = UITableViewCellAccessoryNone;
self.lastSelectedIndexPath = indexPath;
}
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
This works great! Now, in Swift, I wrote:
override func viewDidLoad() {
super.viewDidLoad()
...
self.tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: "categoryCell")
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier("categoryCell", forIndexPath: indexPath) as UITableViewCell
cell.textLabel?.text = categories[indexPath.row]
let row = indexPath.row;
if let lastIndexPath = self.lastSelectedIndexPath {
cell.accessoryType = (lastIndexPath.row == row) ? UITableViewCellAccessoryType.Checkmark : UITableViewCellAccessoryType.None;
}
return cell
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
self.tableView.deselectRowAtIndexPath(indexPath, animated: true)
let newRow = indexPath.row;
var oldRow: Int?
if let lastIndexPath = self.lastSelectedIndexPath {
oldRow = lastIndexPath.row;
let oldCell = self.tableView(tableView, cellForRowAtIndexPath: lastIndexPath)
oldCell.accessoryType = UITableViewCellAccessoryType.None;
}
if (newRow != oldRow) {
let newCell = self.tableView(tableView, cellForRowAtIndexPath: indexPath)
newCell.accessoryType = UITableViewCellAccessoryType.Checkmark;
self.lastSelectedIndexPath = indexPath;
}
}
And this doesn't work. The checkmark appears only sometimes and it disappears when I scroll. I spent two hours to figure out why but without success.
The main issue is that you call tableView(_:cellForRowAtIndexPath:)
instead of tableView.cellForRowAtIndexPath(_:)
and thus create a new cell instead of getting the one currently displayed.
Here's some cleanup:
override func viewDidLoad() {
super.viewDidLoad()
// …
tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: "categoryCell")
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("categoryCell", forIndexPath: indexPath) as UITableViewCell
cell.accessoryType = (lastSelectedIndexPath?.row == indexPath.row) ? .Checkmark : .None
cell.textLabel?.text = categories[indexPath.row]
return cell
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
tableView.deselectRowAtIndexPath(indexPath, animated: true)
if indexPath.row != lastSelectedIndexPath?.row {
if let lastSelectedIndexPath = lastSelectedIndexPath {
let oldCell = tableView.cellForRowAtIndexPath(lastSelectedIndexPath)
oldCell?.accessoryType = .None
}
let newCell = tableView.cellForRowAtIndexPath(indexPath)
newCell?.accessoryType = .Checkmark
lastSelectedIndexPath = indexPath
}
}