UIImage saved to Document Directory returning nil

Question

NSDocumentDirectoryI'm new to iOS. Im trying to build a simple app to better grasp Core Data and the file system. I can't retrieve data that I've apparently stored.

-I check to see if the file exists at the path, which it does, but when I try to NSLog the data and that returns null.

Any help is much appreciated. My gut is that this is a scoping or memory retention issue but I can't figure it out.

This is the saving method from UIImagePicker

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImage *imageToAdd = info[UIImagePickerControllerOriginalImage];
    NSData *pngsData = UIImagePNGRepresentation(imageToAdd);
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *docPath = [paths objectAtIndex:0];
    NSString *filePath = [docPath stringByAppendingFormat:@"%@.png",[self getdateAndTime]];
    NSError *error;
    BOOL succcess = [pngsData writeToFile:filePath options:NSDataWritingAtomic error:&error];
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
        NSLog(@"The file exists");
    }

    if (error !=nil) {
        NSLog(@"errorIS %@", error);
    }

    CoreDataStack *cds = [CoreDataStack defaultStack];
    Photo *photo = [NSEntityDescription insertNewObjectForEntityForName:@"Photo" inManagedObjectContext:cds.managedObjectContext];
    photo.photoName = filePath;
    [cds saveContext];

    [self dismissViewControllerAnimated:YES completion:nil];
    [self.collectionView reloadData];
}

This is the code to retrieve the stored data the Collection View

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    PhotoCollectionViewCell *photoCell = (PhotoCollectionViewCell*)[collectionView dequeueReusableCellWithReuseIdentifier:@"photoCell" forIndexPath:indexPath];
    Photo *photo = [self.fetchedResultsController objectAtIndexPath:indexPath];
    NSLog(@"%@",photo.photoName);

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *imageLocation = [documentsDirectory stringByAppendingString:photo.photoName];
    NSData *data = [NSData dataWithContentsOfFile:imageLocation];
    UIImage *image = [UIImage imageWithData:self.testImageData];
    NSLog(@"%@", data);

    photoCell.cellImage.image = image;
    photoCell.layer.borderColor = [[UIColor blackColor] CGColor];
    photoCell.layer.borderWidth = 2.0;

    return photoCell;
}

FYI - you are mistakenly using the Documentation directory instead of the Documents directory. — rmaddy, Jan 24 '15 at 18:14
Wow.. thank you for the catch. I fixed it and the problem is still persisting — got2jam, Jan 24 '15 at 18:18
Do not check `error` for `!nil`, check the return variable (`success`) for `nil`. — zaph, Jan 24 '15 at 18:18
Note: a simple NSLog of the path by the OP would have shown the problem. — zaph, Jan 24 '15 at 18:21

rmaddy · Accepted Answer · 2015-01-24T18:32:31.390

You have a several issues:

~~Replace NSDocumentationDirectory with NSDocumentDirectory.~~

You are building your paths incorrectly. This:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
NSString *docPath = [paths objectAtIndex:0];
NSString *filePath = [docPath stringByAppendingFormat:@"%@.png",[self getdateAndTime]];

should be:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docPath = [paths objectAtIndex:0];
NSString *filename = [NSString stringWithFormat:@"%.png", [self getdataAndTime]];
NSString *filePath = [docPath stringByAppendingPathComponent:filename];

Note the use of stringByAppendingPathComponent:. This is important. Without it you end up with:

.../sandboxpath/Documentsfilename.png

instead of:

.../sandboxpath/Documents/filename.png

Make the same fix in both methods.

You are saving the fullpath to your Photo object. Never save absolute paths. They change over time. Only save the filename relative to Documents. So change:
```
photo.photoName = filePath;
```
to:
```
photo.photoName = filename;
```
When you read the value back in the future, append it to the Document path.

Your error checking should be:

if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
    NSLog(@"The file exists");
} else {
    NSLog(@"errorIS %@", error);
}

Thank you for the detailed help with explanation. It's very much so appreciated. — got2jam, Jan 24 '15 at 18:37

score 1 · Answer 2 · edited May 23 '17 at 12:02

1

Your file is likely not being found on load because your stored path contains pieces that can change from build to build. Check out this question for a similar issue/result.

Can't find saved file (in device) after restarting the app

Best answer: don't store the mutable parts; fallback answer: make sure you replace the mutable parts with current values.

edited May 23 '17 at 12:02

Community

1
1

answered Jan 24 '15 at 18:23

Brad Brighton

2,179
1
13
15

This was actually going to be my next problem to address but rmaddy's fix addressed that as well – got2jam Jan 24 '15 at 18:38

UIImage saved to Document Directory returning nil

2 Answers2