Question

My app has a user select a photo from the picker. I apply the selected image to a view and then I save it to a file and reference that file in user defaults so when the UserProfile is created that avatar is loaded in.

When I close the app and then start it again, the app loads the image from the file. After loading the image from the file, my app is crashing when I apply it to an Image view because it is seen as an __NSCFArray. There is no method scale on __NSCFArray. Why is it being cast to this class?

-[__NSCFArray scale]: unrecognized selector sent to instance 0x145260

* Terminating app due to uncaught exception
‘NSInvalidArgumentException’, reason: ‘[__NSCFArray scale]:
unrecognized selector sent to instance 0x145260’

Here is my code where the UIImage is created from a file:

@implementation UserProfile 

- (id) init {
    self = [super init];
    if(self) {      
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    _username = (NSString *)[userDefaults objectForKey:USERNAME_KEY];
    NSString *filename = (NSString *) [userDefaults objectForKey:@"AvatarFilename"];
    NSLog(@"filename from user defaults: %@",filename);
    if (filename) {
            _avatar = [UIImage imageWithContentsOfFile:filename];
            if (!_avatar) NSLog(@"LOGERROR: avatar was not created from file");
                _customAvatar = TRUE;
            } else {
                _customAvatar = FALSE;
                _avatar = [UIImage imageNamed:DEFAULT_AVATAR_FILENAME];
                if (!_avatar) NSLog(@"LOGERROR: avatar was not created from default");
            }
        [self createThumbnail];        
    }
    return self;
}

Note: in my createThumbnail code I call this [_avatar isKindOfClass:[UIImage class] and it says it is a UIImage. But then when I set the view, it thinks it is an __NSCFArray. I don’t even understand how this is possible since the property is a UIImage *.

This is how the image is persisted

- (void) setAvatar:(UIImage *)image
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    NSString *filename = nil;

    if (image) {
        if (_avatar) [_avatar release];
        _avatar = [image retain];
        _customAvatar = TRUE;
    filename = [NSString stringWithFormat:@"%@/%@",[MyUtilities applicationDocumentsDirectory],AVATAR_FILENAME];
        if (![UIImagePNGRepresentation(image) writeToFile:filename atomically:YES])
            NSLog(@"LOGERROR: Failure to write avatar file");
        else NSLog(@"saved avatar to PNG file");
    } else {
        NSLog(@"setting default avatar");
        _avatar = [UIImage imageNamed:DEFAULT_AVATAR_FILENAME]; 
        _customAvatar = FALSE;
    }

    [userDefaults setObject:filename forKey:AVATAR_KEY];
    // TODO If performance is crucial, consider creating a default thumbnail as well
    [self createThumbnail];

    if(![userDefaults synchronize])
    { 
        NSLog(@"LOGERROR: Failure to synchronize userDefaults");
    }

}

To my knowledge I am not receiving a memory warning.

Answer 1

You are saving autoreleased object (return by imageNamed: and imageWithContentsOfFile:) without retaining in init. You can replace that method with next one:

- (id) init {
    self = [super init];
    if(self) {      
        NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
        _username = (NSString *)[userDefaults objectForKey:USERNAME_KEY];
        NSString *filename = (NSString *) [userDefaults objectForKey:@"AvatarFilename"];
        NSLog(@"filename from user defaults: %@",filename);
        if (filename) {
            _avatar = [[UIImage imageWithContentsOfFile:filename] retain];
            if (!_avatar) NSLog(@"LOGERROR: avatar was not created from file");
            _customAvatar = TRUE;
        } else {
            _customAvatar = FALSE;
            _avatar = [[UIImage imageNamed:DEFAULT_AVATAR_FILENAME] retain];
            if (!_avatar) NSLog(@"LOGERROR: avatar was not created from default");
        }
        [self createThumbnail];        
    }
    return self;
}

You don’t need to retain this object anymore.
Just release it in dealloc.

In setAvatar: you should also retain returned by imageNamed: value : _avatar = [[UIImage imageNamed:DEFAULT_AVATAR_FILENAME] retain];