Question

I’m very new to Objective-C, and am having some beginner issues. I have an application that has an area that is supposed to behave somewhat like a photo gallery. The user chooses a picture from their camera roll, and the photos get displayed in UIImageViews. I’m trying to save the image that they select. I have 9 UIImageView’s, and the issue is that when I select a different photo for each UIImageView, close and relaunch the app, the other 8 UIImageViews display the photo that is stored in the first image view. Here is the code that I’m working with:

- (NSString *)dataFilePath {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(
                                                         NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    return [documentsDirectory stringByAppendingPathComponent:kFilename9];
}

- (void)applicationDidEnterBackground:(UIApplication*)application {
    NSLog(@"Image on didenterbackground: %@", imageView);
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView2.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView3.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView4.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView5.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView6.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView7.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView8.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView9.image)];

    [self.imageData writeToFile:[self dataFilePath] atomically:YES];
    NSLog(@"The image is: %@", [[imageView image] description]);
    NSLog(@"dataFilePath is: %@", [self dataFilePath]);

}

- (void)viewDidLoad
{

    NSString *filePath = [self dataFilePath];
    NSLog(@"FilePath: %@", filePath);
    NSLog(@"Image: %@", imageView);
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
        NSData *vdlData = [[NSData alloc] initWithContentsOfFile:filePath];
        imageView.image = [[UIImage alloc] initWithData:vdlData];
        imageView2.image = [[UIImage alloc] initWithData:vdlData];
        imageView3.image = [[UIImage alloc] initWithData:vdlData];
        imageView4.image = [[UIImage alloc] initWithData:vdlData];
        imageView5.image = [[UIImage alloc] initWithData:vdlData];
        imageView6.image = [[UIImage alloc] initWithData:vdlData];
        imageView7.image = [[UIImage alloc] initWithData:vdlData];
        imageView8.image = [[UIImage alloc] initWithData:vdlData];
        imageView9.image = [[UIImage alloc] initWithData:vdlData];
    }


    UIApplication *app = [UIApplication sharedApplication];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(applicationDidEnterBackground:)
                                                 name:UIApplicationDidEnterBackgroundNotification
                                               object:app];

    [super viewDidLoad];

}

I’m trying to figure out what I need to change to get the UIImageViews to display the correct pictures, rather than them all displaying the same picture. This is probably a simple fix, but any help would be greatly appreciated, thanks!

Answer 1

Okay, here’s how I would do it:

Use NSUserDefaults to save your images as a mutable array:

ViewController.h

@property(retain) NSUserDefaults *user;

ViewController.m

@synthesize user;

- (void)viewWillAppear:(BOOL)animated
{

    self.user = [NSUserDefaults standardUserDefaults];

Edit

    NSMutableArray* array = [[self.user objectForKey:@"images"]mutableCopy];
    while(array == nil)
    {
       [self.user setObject:[NSMutableArray arrayWithObject:@""] forKey:@"images"]
       array = [[self.user objectForKey:@"images"]mutableCopy];
       NSLog(@"%@",@"attempting to create an array to store the images in");
    }

End Edit
}

- (void)applicationDidEnterBackground:(UIApplication*)application {
    NSLog(@"Image on didenterbackground: %@", imageView);
    NSMutableArray* array = [NSMutableArray arrayWithObject:[NSData dataWithData:UIImagePNGRepresentation(imageView.image)]];

    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView2.image)];
    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView3.image)];
    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView4.image)];
    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView5.image)];
    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView6.image)];
    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView7.image)];
    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView8.image)];
    [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView9.image)];

    [self.user setObject:array forKey:@"images"];

}

- (void)viewDidLoad
{
    NSMutableArray* array = [[self.user objectForKey:@"images"]mutableCopy];

EDIT

    if(array.count == 9)
    {
    imageView.image = [[UIImage alloc] initWithData:[array objectAtIndex:0]];
    imageView2.image = [[UIImage alloc] initWithData:[array objectAtIndex:1]];
    imageView3.image = [[UIImage alloc] initWithData:[array objectAtIndex:2]];
    imageView4.image = [[UIImage alloc] initWithData:[array objectAtIndex:3]];
    imageView5.image = [[UIImage alloc] initWithData:[array objectAtIndex:4]];
    imageView6.image = [[UIImage alloc] initWithData:[array objectAtIndex:5]];
    imageView7.image = [[UIImage alloc] initWithData:[array objectAtIndex:6]];
    imageView8.image = [[UIImage alloc] initWithData:[array objectAtIndex:7]];
    imageView9.image = [[UIImage alloc] initWithData:[array objectAtIndex:8]];
    }

END EDIT

    UIApplication *app = [UIApplication sharedApplication];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(applicationDidEnterBackground:)
                                             name:UIApplicationDidEnterBackgroundNotification
                                           object:app];

    [super viewDidLoad];

}

- (void)viewDidUnload
{
    self.user = nil;
}

This way, you will not lose the images or data, they will be stored and easily accessed, and they will not disappear even if you update your app.

Cheers!