NSMutableArray Add and Save Objects - ios

Question

New to iOS and am stuck on one issue in regards to adding objects in NSMutable Array and displaying the array on another view within the App. The data displays fine on other view in TableView, but when I add another item to the Array (using code below), it just replaces what was there, not adding to the array.
- (void) postArray {
tableData = [[NSMutableArray alloc] initWithCapacity:10];
tableData = [[NSMutableArray alloc] initWithObjects: nil];
[tableData addObject:favShot]; }
-(NSString *) saveFilePath {
NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, TRUE);
return [[path objectAtIndex:0] stringByAppendingPathComponent:#"savefile.plist"]; }
- (void) viewWillDisappear:(BOOL)animated: (UIApplication *) application {
NSArray *values = [[NSArray alloc] initWithObjects:tableData, nil];
[values writeToFile:[self saveFilePath] atomically: TRUE]; }
- (void)viewDidLoad {
tableData = [[NSMutableArray alloc] initWithObjects: nil];
NSString *myPath = [self saveFilePath];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:myPath];
if (fileExists)
{
NSArray *values = [[NSArray alloc] initWithContentsOfFile:myPath];
tableData = [values mutable copy];
}
UIApplication *myApp = [UIApplication sharedApplication];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(applicationDidEnterBackground:)
name:UIApplicationDidEnterBackgroundNotification
object:myApp];
[super viewDidLoad]; }
Thank you.

Answer 1

Every time you call postArray you're creating an instance of NSMutableArray, then throwing it away (leaking it if you aren't using ARC). Then you're creating another instance of NSMutableArray. Then you're adding an object (favShot) to that second instance.
Next time you call postArray it's going to throw away your old array and create 2 new ones.
What you want to do is create the tableData instance when you create the controller instance, or when the view loads. Then, don't set tableData = ... as that will discard the old instance. Just add and remove objects.
edit
- (void) postArray {
[tableData addObject:favShot];
}
- (NSString *)saveFilePath {
NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, TRUE);
return [[path objectAtIndex:0] stringByAppendingPathComponent:#"savefile.plist"];
}
- (void) viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
[tableData writeToFile:[self saveFilePath] atomically: TRUE];
}
- (void)viewDidLoad {
NSString *myPath = [self saveFilePath];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:myPath];
if (fileExists)
{
tableData = [[NSMutableArray alloc] initWithContentsOfFile:myPath];
} else {
tableData = [[NSMutableArray alloc] initWithObjects: nil];
}
UIApplication *myApp = [UIApplication sharedApplication];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(applicationDidEnterBackground:)
name:UIApplicationDidEnterBackgroundNotification
object:myApp];
[super viewDidLoad];
}

Answer 2

Try
- (void) viewWillDisappear:(BOOL)animated: (UIApplication *) application
{
NSString *filePath = [self saveFilePath];
NSMutableArray *savedArray = [NSMutableArray arrayWithContentsOfFile:filePath];
if (!savedArray) savedArray = [NSMutableArray array];
[savedArray addObject:tableData];
[savedArray writeToFile:filePath atomically:YES];
}