NSMutableArray objectatindex always shows the last Object - cocoa-touch

my problem is that my NSMutableArray always get the last element with the objectatindex-method.
I have an array with some classes derived from UIViewController. I want to show one View after another.
first i fill the array:
ContactViewController *ContactView = [[ContactViewController alloc]init];
QuestionViewController *QuesView = [[QuestionViewController alloc]init];;
ContactView.mydelegate = self;
[QuesView setDelegate:self];
[Views addObject:ContactView];
Views =[[NSMutableArray alloc]initWithCapacity:11];
for (int i = 0; i < 11; i++) {
[QuesView setParam:#"text" :i ];
[Views addObject:QuesView];
}
after that i want to get the actual view and jump to the next like that:
-(IBAction)Button:(id)sender
{
UIViewController *newView = [[UIViewController alloc]init];
newView = (UIViewController*)[Views objectAtIndex:enumerator];
[self presentViewController:newView animated:YES completion: nil];
enumerator++;
//dismiss old view here....
NSLog(#"number %d",[newView getNumber]);
}
the new view is not shown and the number in the log is always the last number of the array. I tried to go with a for loop through all element in "Views" but there is always the last number in every object....
any hints?

You probably want to create multiple QuestionViewController instances. But you actually create only one object and call setParam on it 11 times.
Also this line [Views addObject:ContactView] has no effect, because you create a new array object and assign it to Views in the next line. The same thing with UIViewController *newView = [[UIViewController alloc]init]. Hope you are using ARC, otherwise this would create a memory leak!

Related

NSMutableArray Resetting Itself?

I am having an issue with NSMutableArray wiping its contents.
Consider my code: (int i; is in my file's .h as is NSMutableArray* newFileControllerArray)
-(void)awakeFromNib{
i = 0;
newFileWindowControllerArray = [[NSMutableArray alloc]init];
}
-(IBAction)newFileMenubar:(id)sender{
[newFileWindowControllerArray addObject:[[NewFileWindowController alloc]initWithWindowNibName:#"NewFileWindowController"]];
NSUInteger elementsInArray = [newFileWindowControllerArray count];
NSLog(#"%lu",(unsigned long)elementsInArray);
[[newFileWindowControllerArray objectAtIndex:i] showWindow:nil];
}
-(IBAction)OKButtonClicked:(id)sender{
NSUInteger elementsInArray = [newFileWindowControllerArray count];
NSLog(#"THERE ARE %lu ELEMENTS IN THE ARRAY",(unsigned long)elementsInArray);
}
The first method called (other than awakeFromNib:) is newFileMenubar: This will add one element to the array. I can confirm that this works because 1 is printed in the console. However, once OKbutton is called and I print out the number of elements in my array it says that no elements are in the array. Why is that?
Am I missing something very obvious here? Why does my array reset itself?
EDIT:
The comments have gotten long and unwieldy so here is the code w/NSLogs and outputs:
-(void)awakeFromNib{
i = 0;
newFileWindowControllerArray = [NSMutableArray array];
NSLog(#"self=%p, array=%p", self, newFileWindowControllerArray);
}
-(IBAction)newFileMenubar:(id)sender{
[newFileWindowControllerArray addObject:[[NewFileWindowController alloc]initWithWindowNibName:#"NewFileWindowController"]];
[[newFileWindowControllerArray objectAtIndex:i] showWindow:nil];
i++;
NSLog(#"self=%p, array=%p", self, newFileWindowControllerArray);
}
-(IBAction)OKButtonClicked:(id)sender{
NSUInteger elementsInArray = [newFileWindowControllerArray count];
NSLog(#"self=%p, array=%p", self, newFileWindowControllerArray);
[documentController newDocument:sender];
[[newFileWindowControllerArray objectAtIndex:i]close];
}
When the program launches, this is the output: self=0x100141480, array=0x100140f30
This should be coming from awakeFromNib:
The next method called is newFileMenubar:
The output from this is
self=0x1001ac990, array=0x1005228a0 and immediately after self=0x100141480, array=0x100140f30
The last method called is OKButtonClicked:
The output from the last method (OKButtonClicked:) is self=0x1001ac990, array=0x1005228a0
As you can see from the code, the name of the array doesn't change, but my outputs beg to differ? What could cause this?
There are good clues in your log output. There are multiple instances of the view controller (see the different values for 'self'?). They each have their own array. See this code...
-(IBAction)newFileMenubar:(id)sender{
[newFileWindowControllerArray addObject:[[NewFileWindowController alloc]initWithWindowNibName:#"NewFileWindowController"]];
When you press the button associated with that action, your app builds another view controller and places it in the array. That view controller gets the awake from nib message and allocates another array, and so on.
To confirm this, change the code as follows:
-(IBAction)newFileMenubar:(id)sender{
[newFileWindowControllerArray addObject:#"Hello world"];
// and comment this out, for now:
// [[newFileWindowControllerArray objectAtIndex:i] showWindow:nil];
In the other methods, comment out your expectations that the array has anything other than strings in it, and see what you get. e.g. ...
- (IBAction)OKButtonClicked:(id)sender {
NSUInteger elementsInArray = [newFileWindowControllerArray count];
NSLog(#"self=%p, array=%p", self, newFileWindowControllerArray);
[documentController newDocument:sender];
// and comment this out, for now:
// [[newFileWindowControllerArray objectAtIndex:i]close];
// instead...
NSLog(#"danh thinks my array will be ok: %#", newFileWindowControllerArray);
}
You probably do not mean to create another view controller on every button press, but I'm not sure what function you do want. Maybe you want an array of views? (To create many view controllers under the control of another, you'll want to read up on container view controllers, here).

Global array loses values after exiting method

At the top of my .m file I have
static NSMutableArray *name;
I load a bunch of values into my *name array inside my viewDidLoad method.
I have a slider that can modify the values inside this array. The slider method is only called when the value of the slider changes. However, I ran this code and every time my program exits the viewDidLoad method I lose the values that were added to the global variable name. I can see that they were there before exiting the viewDidLoad method.
What am I doing wrong?
EDIT: Inside viewDidLoad
if (name == nil)
name = [NSMutableArray array];
UITextField *nameTemp = [[UITextField alloc] initWithFrame:CGRectMake(20,20,20,20)];
nameTemp.returnKeyType = UIReturnKeyDone;
etc
[self.view addSubview: nameTemp];
[name addObject:nameTemp]
[nameTemp release];
[NSMutableArray array] creates an autoreleased array that apparently is being released at the end of your viewDidLoad method. Try using [[NSMutableArray alloc] init] or [[NSMutableArray array] retain] and see if the values persist after viewDidLoad returns.

How to passing a NSMutableArray to another ViewController class

I have created NSMutale Array in "HeroListViewController". I want use it in another viewController which is MapTutorialViewController. I tried like this.
in HeroListViewController.h
MapTutorialViewController *maptutorialcontroller;
NSMutableArray *listData;
set properties and synthesize them correctly
in HeroListViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
listData = [[NSMutableArray alloc] init];
}
- (UITableViewCell *)tableView:(UITableView *)theTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *HeroTableViewCell = #"HeroTableViewCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:HeroTableViewCell];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:HeroTableViewCell] autorelease];
}
NSManagedObject *oneHero = [self.fetchedResultsController objectAtIndexPath:indexPath];
NSInteger tab = [tabBar.items indexOfObject:tabBar.selectedItem];
switch (tab) {
case kByName:
cell.textLabel.text = [oneHero valueForKey:#"name"];
cell.detailTextLabel.text = [oneHero valueForKey:#"secretIdentity"];
break;
case kBySecretIdentity:
cell.detailTextLabel.text = [oneHero valueForKey:#"name"];
cell.textLabel.text = [oneHero valueForKey:#"secretIdentity"];
default:
break;
}
[listData addObject: [oneHero valueForKey:#"secretIdentity"]];
count=[listData count];
printf("No of items of listData:%u\n", count);
if(maptutorialcontroller==nil){
maptutorialcontroller= [[MapTutorialViewController alloc]initWithNibName:#"MapTutorialViewController" bundle:nil];
maptutorialcontroller.secondarray=listData;
}
count=[maptutorialcontroller.secondarray count];
printf("No of items of seconarray :%u\n", count);
return cell;
}
OUTPUTS : No of items of listData:3
No of items of seconarray :3 // both are correct
BUT the the problem I have, when I try to use the secondarray in "MapTutorialViewController" like this,
in MapTutorialViewController.h
HeroListViewController *heroviewcontroller;
NSMutableArray *secondarray;
set properties and synthesize them correctly
in MapTutorialViewController.m
- (void)viewDidLoad
{
heroviewcontroller = [[HeroListViewController alloc]initWithNibName:#"HeroListViewController" bundle:nil];
self.secondarray=[heroviewcontroller.listData mutableCopy];
//secondarray= heroviewcontroller.listData;
int count;
count = [secondarray count];
//
printf("No of items of secondarray from MapTutorialViewContriller :%u\n", count);
}
OUTPUT : No of items of secondarray from MapTutorialViewContriller :0
Why it is 0
whats the wrong with my code, please help me
Example
firstviewcontroller .h file
before #interface
use #class secondViewcontroller;
declare this inside of #interface with
secondViewcontroller *sVC;
then in firstViewController.m file
before #implementation
#import "secondViewcontroller.h"
then
-------------------
secondVC.h file
#interface inside declare this
say NSMutableArray *secondarray;
and sythasize them.
-------------------
after this
in firstViewcontroller.h viewdidload create this sVC by alloc and initwithnibname then
sVC.secondArray=urfirstArray;
now while u push this sVC controller to navigation controller u can nslog this array in viewdidload.
This would only work if you create and fill the mutable array in the init method.
You should look into delegation and/or notification.
How is that array being created within HeroListViewController? In this method, you are creating a NEW instance of HeroListViewController and trying to get a property from it. If you already have a HeroListViewController in memory, this is completely wrong.
Make a property on the class for this viewDidLoad method. It should be of type NSMutableArray. When you allocate and initialize this class, call [set myArray:heroListArray] on it from HeroListViewController. That should give you access to it.
I'm assuming that you have a view containing this new view and the hero list view. If that is the case, then you could create a property in the new view like so:
#property (nonatomic,retain)HeroListViewController *heroListViewController;
and then set it equal to the heroList from the outside:
newView.heroListViewController = HeroListViewController;
The main problem with your code at the moment is that you're creating a new instance of HeroListViewController by using alloc init, and you're not accessing the same thing. By setting the new view's heroListViewController property, you can get access to the correct viewController.
Finally, in viewDidLoad of the new view - I'd actually put the code in viewWillAppear:(BOOL)Animated - you can put code to match the arrays.
Note that this whole way of doing it is messy and could be better done with a singleton class if you need access to an array in multiple places. The above will help you get it working quick, but if you want a really clean fix, go here: http://www.iphonedevsdk.com/forum/iphone-sdk-tutorials/24135-singleton-classes.html

Editing one object in an NSMutableArray also changes another object in the NSMutableArray

I had a navigation application that was working normally. In the table view, the last item is called "add item", and if the user pressed it, it would create a new object and pass it to another view where the user could enter the details for that object. When the user returned to the previous screen, the new object would show in the array which was displayed in the table.
I changed it so that the "add item" field is always the first field in the table, not the last. I made the appropriate changes so that the array would display correctly on the table. However, now I am noticing strange behavior.
If I edit the first object in the array, the 7th object also changes to be the same as this object. If I edit the second object in the array, the fourth and sixth object also change to be the same. If I edit the third item in the array, the fifth object changes to be the same.
What could be happening?
In the viewDidLoad: method I initialize the object like this:
PersonDetails *personDetails = [[PersonDetails alloc] init];
This is the method that gets executed when a user selects a row on the table
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// Navigation logic may go here. Create and push another view controller.
updatePersonArray = YES;
arrayIndex = indexPath.row-1;
editPerson = [[EditClassController alloc] initWithNibName:#"EditPerson" bundle:nil];
editPerson.title = #"Edit Person";
if (arrayIndex != -1) {
personDetails = [classArray objectAtIndex:arrayIndex];
}
else {
personDetails = [[PersonDetails alloc] init];
}
editPerson.personDetails = personDetails;
[self.navigationController pushViewController:editPerson animated:YES];
[editPerson release];
}
This is what the viewWillAppear looks like. It will update the table after an object has been edited.
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
if ([personDetails isEmpty]) {
updatePersonArray = NO;
}
if (updatePersonArray) {
if (arrayIndex == -1) {
NSLog(#"adding new object to array");
[personArray addObject:personDetails];
}
else {
NSLog(#"replacing object at index %d", arrayIndex);
[personArray replaceObjectAtIndex:arrayIndex withObject:personDetails];
}
[self saveArrayToDisk];
[self.tableView reloadData];
updatePersonArray = NO;
}
else {
//load the array from disk
NSLog(#"loading array from disk");
NSData *theData = [[NSUserDefaults standardUserDefaults] objectForKey:#"personArray"];
if (theData != nil) {
NSLog(#"found something");
personArray = [[NSMutableArray alloc] initWithArray:[NSKeyedUnarchiver unarchiveObjectWithData:theData]];
}
else {
personArray = [[NSMutableArray alloc] init];
}
}
}
Edit: I solve the problem by implementing NSCopy for the person object and then making a copy of the object from the array instead of directly pointing to the object in the array. Anyone know why this solved the problem?
Edit: I solve the problem by
implementing NSCopy for the person
object and then making a copy of the
object from the array instead of
directly pointing to the object in the
array. Anyone know why this solved the
problem?
The original problem was pretty much guaranteed to be an issue of having the same PersonDetails in the array multiple times. If you were to do something like:
for (id p in myArray) NSLog("%p", p);
I'd bet that some of the addresses would be the same, indicating same object in array multiple times.
Which is why copying the object "fixed" the problem. You are hiding the dodgy logic that led to the above situation by making a copy on every insertion.
this part here looks a bit dodgy with regard to memory ownership:
if (arrayIndex != -1) {
// here you get back an autorelease object - which you haven't retained
personDetails = [classArray objectAtIndex:arrayIndex];
}
else {
// here you create an object with retainCount =1
personDetails = [[PersonDetails alloc] init];
}
// depending on your property attribute this may or may not work as you expect
editPerson.personDetails = personDetails;
i.e. #property(??) personDetails

Issues declaring already existing NSMutableArray in new class

I have a class (DataImporter) which has the code to download an RSS feed. I also have a view and separate class (TableView) which displays the data in a UITableView and starts the parsing process, storing parsed information in an NSMutableArray (items) which is located in the (TableView) subclass.
Now I wish to add a UIMapView which displays the items in the (items) NSMutableArray. Herein lies the issue - I need to somehow get the data from the (items) NSMutableArray into the new (mapView) subclass which I'm struggling with - and I preferably don't want to have to create a new class to download the data again for the mapView class when it already is in the applications memory. Is there a way I can transfer the information from the NSMutableArray (items) class to the (mapView) class (i.e. how do I declare the NSMutableArray in the (mapView) class)?
Here's a overview of how the system works:
App opened> Data downloaded (using DataImporter class) when (TableView) viewDidLoad runs> Data stored in NSMutableArray accessible by the (TableView) class> And from here I need to access and declare the array from a new (mapView) class.
Any help greatly appreciated, thanks.
Code for viewDidLoad MapKit:
Data *data = nil;
NSString *ilocation = [data locations];
NSString *ilocation2 = #"New Zealand";
NSString *inewlString;
inewlString = [ilocation stringByAppendingString:ilocation2];
NSLog(#"inewlString=%#",inewlString);
if(forwardGeocoder == nil)
{
forwardGeocoder = [[BSForwardGeocoder alloc] initWithDelegate:self];
}
// Forward geocode!
[forwardGeocoder findLocation: inewlString];
Code for parsing data into original NSMutable Array:
- (void)beginParsing {
NSLog(#"Parsing has begun");
//self.navigationItem.rightBarButtonItem.enabled = NO;
// Allocate the array for song storage, or empty the results of previous parses
if (incidents == nil) {
NSLog(#"Grabbing array");
self.datas = [NSMutableArray array];
} else {
[datas removeAllObjects];
[self.tableView reloadData];
}
// Create the parser, set its delegate, and start it.
self.parser = [[DataImporter alloc] init];
parser.delegate = self;
[parser start];
}
Since you have a property self.datas you can get a reference to the data just by calling that from your UIMapView, or by assigning to some target property in your map view from whatever object controls both views:
mapView.someArrayProperty = tableView.datas
However, you might want to rethink your overall program structure. Keeping what is in effect model data inside views is not good practice and tends make things pretty spaghetti-like as you add more objects and functionality.