iOS: Issue Saving Photo - objective-c

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!

Answer 2

Before I start with the solution, I have to warn you that the way you're doing this isn't the right one. I suggest that you start learning iOS development from the ground up. Apple's own documentation is a pretty good start. http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/Introduction/Introduction.html
Now, back to your question. What you do here is save only one image, not all 9 of them. You set self.imageData always with each image you process and you overwrite its previous value, making only the last image to be saved to file.
So, in order to make your code working, you would have to use an imageData object for each image view, then write that data object to file.
In your case, it's probably best to optimize the code by using loops, instead using multiple objects (like imageView, imageView2, ...).
Also, make sure that you take care of your memory. e.g. imageView.image is allocated but not released.

Answer 3

Well, I see two issues. First and foremost, in viewDidLoad, all your images are getting initWithData:vdlData... so they're all getting the same data. That's why they're all the same.
Also, when you're trying to save them, in ...didEnterBackground, you are overwriting the value of imageData over and over again... when you save it, it's just the last one you've assigned to imageData. You probably want to create an NSArray, and store them in there, pulling them out of the array in viewDidLoad.