CODEWITHSUNDEEP
iosuitableviewuidatepicker
asjj
asjj

Reputation: 543

dequeueReusableCellWithIdentifier takes 0.5 seconds for cell containing UIDatePicker

I have a dynamic tableview where a cell is selected and shows another cell containing a UIDatePicker below it - like in the calendar app.

This works really well but I am having trouble with the initial load of the cell when it is first scrolled to by the user (when it has a height of 0).

Investigating why it was slow I wrapped the dequeueReusableCellWithIdentifier call in NSLogs to look at timings.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *CellIdentifier = [[cellIdentifiers objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
    NSLog(@"Creating cell:%@", CellIdentifier);
    UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
    NSLog(@"Finished cell:%@", CellIdentifier);
    return cell;
}

The NSLog shows this:

14:47:42.427 Creating cell:Date
14:47:42.437 Finished cell:Date
14:47:42.470 Creating cell:DatePicker
14:47:43.006 Finished cell:DatePicker
14:47:43.046 Creating cell:Time
14:47:43.055 Finished cell:Time
14:47:44.753 Creating cell:DatePicker
14:47:45.253 Finished cell:DatePicker

Date/Time are cells containing 2 UILabels and DatePicker is the cell containing a UIDatePicker.

The UIDatePicker cell takes around half a second to complete. After the first time scrolling it loads much faster so there is no noticeable lag - except for the first time the date cell is tapped and so the DatePicker cell below it changes it's height from 0 to 220.

NSLog for first opening the cell:

14:59:34.334 Creating cell:DatePicker
14:59:34.877 Finished cell:DatePicker

I've noticed the calendar app has a slight delay when opening the UIDatePicker cell for the first time but this doesn't seem to be as long as it takes in my app.

I'm testing on an iPhone 4 which may be a contributing factor.

Does anyone have any ideas on what I could be doing wrong or could do to make this faster?

Upvotes: 4

Views: 1457

Answers (1)

asjj
asjj

Reputation: 543

I have solved this by removing the UIDatePicker from the cell, creating a UIDatePicker programmatically and adding it as a subview to the cells contentView in cellForRowAtIndexPath.

I initialise a datePicker and timePicker in viewDidLoad.

- (void)viewDidLoad
{
    [super viewDidLoad];
    datePicker = [[UIDatePicker alloc] init];
    [datePicker setDatePickerMode:UIDatePickerModeDate];
    timePicker = [[UIDatePicker alloc] init];
    [timePicker setDatePickerMode:UIDatePickerModeTime];
}

Then in cellForRowAtIndexPath:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell;
    NSString *CellIdentifier = [[cellIdentifiers objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];

    cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    if ([CellIdentifier isEqualToString:@"DatePicker"] && datePickerOpen)
    {
        [cell.contentView addSubview:datePicker];
    }
    else if ([CellIdentifier isEqualToString:@"TimePicker"] && timePickerOpen)
    {
        [cell.contentView addSubview:timePicker];
    }

    return cell;
}

Upvotes: 5

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