Table cell refresh through timer

[mademo]

Hi all,

I'm doing something and haven't been able to make it work properly yet. This is what I do: I have a TableViewController managing a table which contains text labels that I'd like to periodically refresh to reflect some new text. Since the text of the label is supposed to change periodically, I'd like the new text showing up in each cell of the table periodically.

To this purpose I start a timer inside the initWithStyle method of the UITableViewController implementation like this:

<code>
timer = [NSTimer scheduledTimerWithTimeInterval1.0) target:self
selector:@selector(update userInfo:nil repeats:YES];
</code>

where update is something like this:

<code>
- (void)updateid)sender {

if (cntDeb == 0) cntDeb = 1;
else cntDeb = 0;

for (CellWrapper *element in displayList) {

if (cntDeb == 0)
element.textOfLabel = @"TEST AA";
else
element.textOfLabel = @"TEST BB";
}

}
</code>

I'm expecting to see the table cell label text flipping between TEST AA and TEST BB every second.
However, this doesn't happen and the table just displays the default text (neither TEST AA or TEST BB). The strange thing is that the cell's label flips between TEST AA and TEST BB after I drag the table with my finger up or down the screen. Only in this way I see the labels changing but not if I don't touch the screen.

Any ideas?
Thanks.

[javid.alimohideen]

Trying refreshing the table data inside the timer

[self reloadData]; // if you have subclassed UITableView else [myTableView reloadData];

[mademo]

great thanks!

[mademo]

hmmm, it seems to work but after a couple of minutes the program on the simulator crashes because of an uncaught exception.

[javid.alimohideen]

Maybe the refresh timer is faster than the animation time. You can try calling view change method after the animation did finish. I don't have access to the exact method names but the
pseudo code would be :

 -(void) swapView {
    //Swap your views here, just maintain the current Index so you can get the view and
   // transition views for currIndex with currIndex + 1
}

-(void) animationDidFinish // this is a made up name but I am very sure a method for this exists{
   [self swapView];
}

Hope it works

[scottiphone]

You could set the timer to not repeat and then after you've completed your action set it again (with no repeat) so you're not at the mercy of it getting way out of sync.

If it's running for awhile and then crashes it could also mean you're not releasing objects (memory fills up, set debug at memory warning to app) or have an object that is released (possibly autoreleased)

[jeff_lamarche]

Unless the data that is changing is outside of your control, this is the correct way to handle it. If YOU are changing the data, YOU should tell the table to reload its data when you change it. This is inefficient, and you really need to be concerned with efficiency when coding for the iPhone.

Also, this:

element.textOfLabel = @"TEST AA";

is probably not what you really want. I think what you probably mean is:

[element.textOfLabel isEqualToString:@"TEST AA"];

Objective-C does not allow overriding operators, so your comparison is a pointer comparison, and since you are creating a new constant, you will never be passed in a value that equals it.

You might also want to consider defining those pointers outside of your loop, probably as static, so you're not allocating new stack variables for every object in displayList.

Also, since these are UI elements, why not set a tag and look at that, rather than doing costly string comparisons? Comparing two ints is an order of magnitude more efficient than comparing NSString objects.