Crash when try to delete picture - ios

Question

I just want the user to just delete a picture by just tapping the picture using a collection view. I am doing this for a month and can't get things straight and even getting confused. My code for to do this is below. I am also getting a memory warning sometimes aswell, If i use the instruments app to look for detail the memory allocation does not get freed and just builds up until crash.
- (void)viewDidLoad
{　　Trash = [NSMutableArray array];
filenames = [NSMutableArray new];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSArray *locationStrings = [[NSArray alloc]initWithObjects:#"Bottoms", #"Dress", #"Coats", #"Others", #"hats", #"Tops",nil ];
for(NSString* location in locationStrings){
NSString *fPath = [documentsDirectory stringByAppendingPathComponent:location];
NSError *error;
NSArray *directoryContent = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:fPath error:&error];
collectionTrash.delegate =self;
collectionTrash.dataSource=self;
for(NSString *str in directoryContent){
NSString *finalFilePath = [fPath stringByAppendingPathComponent:str];
[filenames addObject:finalFilePath];
}
}
}
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
NSLog(#"j");
return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return [filenames count];
NSLog(#"b");
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"ReuseID";
TrashCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
UIImageView *imageInCell = (UIImageView*)[cell viewWithTag:1];
NSString *cacheKey = filenames[indexPath.item];
imageInCell.image = [self.imageCache objectForKey:cacheKey];
if (imageInCell.image == nil) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
UIImage *image = [UIImage imageWithContentsOfFile:filenames[indexPath.item]];
if (image) {
[self.imageCache setObject:image forKey:cacheKey];
dispatch_async(dispatch_get_main_queue(), ^{
TrashCell *updateCell = (id)[collectionView cellForItemAtIndexPath:indexPath];
UIImageView *imageInCell = (UIImageView*)[updateCell viewWithTag:1];
imageInCell.image = image;
});
}
});
}
return cell;
}
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
NSLog(#"s:%d", [Trash count]);
NSString *trashBin = [Trash objectAtIndex:indexPath.row];
NSLog(#"k%#l",trashBin);
[filenames removeObjectAtIndex:indexPath.row];
[Trash removeObjectAtIndex:indexPath.row];
[self deleteMyFiles:trashBin];
[collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObjects:indexPath, nil]];
}
NSString *myFileName;
-(void) deleteMyFiles:(NSString*)filePath {
NSError *error;
if([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
[[NSFileManager defaultManager] removeItemAtPath:filePath error:&error];
} else {
NSLog(#"%#",filePath);
}
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
[self.imageCache removeAllObjects];
}
When I try to tap a log comes out saying below.
*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'
*** First throw call stack:
(0x30afbe83 0x3ae5c6c7 0x30a31d95 0x638e9 0x3349d76f 0x3349d495 0x33406ea3 0x33406ea3 0x332781a1 0x332af9fd 0x332af3ab 0x33284d79 0x33283569 0x30ac6f1f 0x30ac63e7 0x30ac4bd7 0x30a2f471 0x30a2f253 0x357632eb 0x332e4845 0x628a5 0x3b355ab7)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

Your Trash array not content any objects.
And you are trying to access object from Trash array
NSString *trashBin = [Trash objectAtIndex:indexPath.row];
Which is the cause of crash.
Note: object name should start with small letters.

Answer 2

In your code, Trash = [NSMutableArray array]; will be autoreleased at some time, so when you access it in '-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath', it has been released. If you are sure there is reason to use this variable instead of using only filenames, you can do this Trash = [[NSMutableArray array] retain]; or Trash = [[NSMutableArray alloc] init]; in your '- (void)viewDidLoad'.

Answer 3

It is not clear what you are trying to do. The notion of "Trash" suggests you are trying to implement a two-stage delete: put items in the trash and at some later time, empty the trash (delete them for good when the user selects an "Empty the Trash" button). But your post and your code suggest a single-stage delete (the user selects to delete with no chance to undo).
Your collectionView:didSelectItemAtIndexPath: delegate method looks particularly confused. As Bhumeshwer correctly points out, your Trash is empty and trying to access any index is causing your crash. No where in this code are you putting anything in Trash But, by simply removing that line of code, I don't think the method will do what you want.
If you are implementing a two-stage delete, I think you simply want to remove the string from filenames and add it to Trash. Don't remove the object from Trash and don't delete files in Trash. Somewhere else (like when the "Empty the Trash" button is selected), call deleteMyFiles to empty the trash.
If you are implementing a single-stage delete, get rid to Trash all together: don't allocate it in viewDidLoad and don't empty it in didSelectItemAtIndexPath. Simply, remove the object from filenames AND update the imageInCell!
Suggestions:
move
collectionTrash.delegate =self;
collectionTrash.dataSource=self;
to wherever collectionTrash is being created and initialized. Inside viewDidLoad and inside the for loop, it is out of context. Your mixing unrelated lines of code making your code unorganized and confusing. At least, move it out of the for loop.
think model-view-controller. What's the model here? Is it filenames or Trash? Is the CollectionView a view of filenames or Trash? What is collectionTrash?
Trash should be trash (as Bhumeshwer points out);
what is NSString *myFileName; and what's it doing there?
don't forget to manage your imageCache. You put images in but don't take them out. When you remove a file from filenames, remove the image from imageCache.
I could go on, but will stop here. Good luck.