Custom UICollectionViewCell increases memory allocation - ios

Question

After finishing my app, I realized that the memory allocation is incredibly huge.
I think I have isolated the problem to a view which makes use of a UICollectionView.
The collection view has custom cell.
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return 12;
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
MyCollectionCell *yearCell = [collectionView dequeueReusableCellWithReuseIdentifier:myCellIdentifier forIndexPath:indexPath];
if (yearCell == nil)
yearCell = [[AgendaYearCollectionCell alloc] init];
yearCell.layer.shouldRasterize = YES;
yearCell.layer.rasterizationScale = [UIScreen mainScreen].scale;
[yearCell setCurrentDate:newDate];
return yearCell;
}
I registered the nib of the custom cell in viewDidLoad:
UINib * nib = [UINib nibWithNibName:#"AgendaYearCollectionCell" bundle:[NSBundle mainBundle]];
[self.collectionView registerNib:nib forCellWithReuseIdentifier:myCellIdentifier];
MyCollectionViewCell is a custom (inherited) UICollectionViewCell and its setCurrentDate method does:
-(void)setCurrentDate:(NSDate *)date
{
if (calendar == nil)
calendar = [[myCalendarView alloc] initWithDate:currentMonth];
[self.contentView addSubview:calendar];
calendar = nil;
[self setNeedsDisplay];
}
The problem is that memory increase linearly as I add/remove new cell to the view.
I was supposing that dequeueReusableCellWithReuseIdentifier does what I need: reuse cells keeping memory usage low.
But this does not happen. For instance, my collection view is a calendar: a grid of 12 months. Therefore, I need always 12 and only 12 cells.
There is a way for a better management of the collection ?

Answer 1

I set my reuse cell identifier here
EDIT:
I think here is your problem, you add calendar each time in collection view delegate,so you just reused your MyCollectionCell but your calendar in MyCollectionCell is not reused.that's why you can see the memory print grow. So , you should make MyCalendarView more reusable so that you don't have to alloc it each time.
-(void)setCurrentDate:(NSDate *)date
{
if (calendar == nil){
calendar = [[myCalendarView alloc] initWithDate:currentMonth];
[self.contentView addSubview:calendar];
// calendar = nil;//here you dealloc calendar which make `if(calendar == nil)` run each time.
[self setNeedsDisplay];
}
}// each calendar in Collection Cell won't be create or refresh again.

Answer 2

Don't init CollectionViewCell like UITabelView cell in cellForItemAtIndexPath. Delete all of these code
// if (yearCell == nil)
// yearCell = [[AgendaYearCollectionCell alloc] init];
// yearCell.layer.shouldRasterize = YES;
// yearCell.layer.rasterizationScale = [UIScreen mainScreen].scale;
Because your cell is Nib cell, bring all these setting into awakeFromNib in MyCollectionCell.m like this
-(void)awakeFromNib{
[super awakeFromNib];
self.layer.shouldRasterize = YES;
}
registerNib is enough in the case of Nib cell, remember specify your MyCollectionCell in Nib cell class.

Answer 3

Use Instruments for analysing your app's memory footprint. In XCode > Product > Profile and select Leaks on Instruments. It is very very useful to trace high memory usage responsible calls.