iOS: UITableView in popover and seeing "double vision" effect - ios

Question

I'm working on an iPad app and at some points, I need to show a popover with options for a user to pick from. For this, I use a UITableView in a UIPopoverController. The problem is that, on an iPad (not on the simulator), when scrolling the tableview, I get a sort of "double vision" effect, where it appears like two sets of of the list exist. One that is stationary, and one that scrolls up and down.
I construct the popover like this:
self.fClassTypeList = [[NSMutableArray alloc] init];
[self.fClassTypeList removeAllObjects];
NSUInteger stringLength = 0;
(populate self.fClassTypeList, and set stringLength to the size of the longest entry)
[self setContentSizeForViewInPopover:CGSizeMake(stringLength * 15.0f, [self.fClassTypeList count] * 30)];
CGFloat tableBorderLeft = 5;
CGFloat tableBorderRight = 5;
CGRect viewFrame = self.view.frame;
viewFrame.size.width -= tableBorderLeft + tableBorderRight; // reduce the width of the table
self.fListOfItems = [[UITableView alloc] initWithFrame:viewFrame style:UITableViewStylePlain];
self.fListOfItems.delegate = self;
self.fListOfItems.dataSource = self;
[self.view addSubview:self.fListOfItems];
I put in the viewDidLayoutSubviews(…) part of the view controller, maybe I should put it somewhere else? I am not sure why this happens on the actual machine, but not the simulator.

Answer 1

-viewDidLayoutSubviews is a weird place to put allocations because that method can be called multiple times. So as far as your main issue goes, I believe you should move your allocations into the -init method, and move your layout code into your -viewWillAppear method.
- (id)init
{
self = [super init];
if (self)
{
self.fClassTypeList = [[NSMutableArray alloc] init];
self.fListOfItems = [[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStylePlain];
self.fListOfItems.delegate = self;
self.fListOfItems.dataSource = self;
[self.view addSubview:self.fListOfItems];
}
return self;
}
- (void )viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
NSUInteger stringLength = 0;
CGFloat tableBorderLeft = 5;
CGFloat tableBorderRight = 5;
CGRect viewFrame = self.view.frame;
viewFrame.size.width -= tableBorderLeft + tableBorderRight; // reduce the width of the table
self.fListOfItems.frame = viewFrame;
[self setContentSizeForViewInPopover:CGSizeMake(stringLength * 15.0f, [self.fClassTypeList count] * 30)];
}
This promotes better memory management.
As an added bonus, I would recommend you refactor the
[self setContentSizeForViewInPopover:CGSizeMake(stringLength * 15.0f, [self.fClassTypeList count] * 30)]; method into a setter method of fClassTypeList. Even better is to simply call -viewWillAppear: in that same setter method instead. This will promote good scalability as you (or someone else) continues to build upon this code later on.
It's a little confusing to see what exactly you're trying to accomplish in this code because it's so hardcoded so let me know if I'm missing the mark you're looking for (w/ an explanation why) and I'll make an edit.
Cheers