Object creation of views and share data between view in iOS - ios

I am new to iOS.I am recently stuck with a problem.
I have a view A and View B. View A has a navigation controller. view A has a button to switch to B.When i am clicking this button every time B creates a new object. how can i track this object to share data between this two view.
Thanks

There are several ways to do this.
You could have a property of B, that A sets before you push. (NSDictionary, Array, String etc)
This not the best way however it would work.
UIViewController *viewB = [[UIViewController alloc]init];
[viewB setMyProperty:#"some data!"];
[self.navigationController pushViewController:viewB animated:YES];
You could also use NSNotificationCenter to pass the object to the next view.
NSDictionary *dictionary = [NSDictionary dictionaryWithObject:
[NSNumber numberWithInt:index]
forKey:#"index"];
[[NSNotificationCenter defaultCenter] postNotificationName:#"myNotification"
object:self
userInfo:dictionary];
The way I usually handle this is to setup and object that holds my data with an associated protocol initialized in my AppDelegate. Then any view that needs to read/write something just grabs a Pointer to that object and runs with it.
#class AppData;
#protocol AppDataProtocol
- (AppData*)theAppData;
#end
in the View you can grab the pointer with this.
-(AppData*)theAppData {
id<AppDataProtocol> theDelegate = (id<AppDataProtocol>)[UIApplication sharedApplication].delegate;
AppData* theData = (AppData*)theDelegate.theAppData;
return theData;
}
and this.
appData = [self theAppData];
You are then able to easily access any property of appData.

-(void)fnButtonA{
ViewB *vcB = [[ViewB alloc] initWithData:DataToB];
[[self navigationController] pushViewController:vcB animated:Yes];
}
In ViewB.m edit the init function to
-(UIViewController *)initWithData:(NSMutableDictionary*)data

Related

Problems reloading data in a tableView

I am trying to reload data in a tableview based on a users account permissions whenever they log in.
The two classes involved in this are:
mainViewController and menuViewController
Currently I am able to use
[self.tableView reloadData];
To reload the data when called within the viewWillAppear method. Which is no good for me since the user hasn't logged in when the view loads so there is no data to populate the table at this point.
I have created a method called populateTable in menuViewController.h which I am calling in the mainViewController.m file on button press using the following;
(IBAction)Reload:(id)sender {
menuViewController *mvc = [[menuViewController alloc]init];
[mvc populateTable];
}
This seems to work correctly as I have an NSLog within the populateTable method which executes. However the reloadData does not work.
Here is my populateTable method;
-(void)populateTable {
self.section1 = [NSMutableArray arrayWithObjects:#"test settings", #"test", #"test",#"Users and access",#"No-track IPs", nil];
self.section2 = [NSMutableArray arrayWithObjects:#"Rules", #"Channels",#"Goals",#"Pages", nil];
self.menu = [NSMutableArray arrayWithObjects:self.section1, self.section2, nil];
[self.tableView reloadData];
NSLog(#"Reloading data");
}
Can you guys help me out here, I have been staring at this all day and getting nowhere, thanks!
From my experience this is likely a problem with timing - the IBOutlet of self.tableView is not ready when you call reloadData on it (add an NSLog and see for yourself - it is nil when called).
To solve this, the populateTable method must be called within the UIViewController's viewDidLoad method. This guarantees that the outlets are not nil and that everything is ready for your data population.
Also, you should not instantiate your MenuViewController with [[MenuViewController alloc] init] but using the storyboard's instantiateViewControllerWithIdentifier.
Your problem is this line,
menuViewController *mvc = [[menuViewController alloc]init];
This creates a new instance of menuViewController, not the one you see on screen. You need to get a reference to the one you have, not create a new one. How you get that reference depends on how, when, and where your controllers are created.

NSNotification sends value that get reset in viewDidLoad

I have this problem:
2 views called A and B, both are TableViewController.
A listen for notification, B sends notification
I'm not going to explain in detail, but for sake of simplicity it's like this:
A can display multiple types of data, B has a list of these types, selecting one row from B makes A load in it's tableView the right list of data.
While i'm in B i'm sending a notification like this
NSNumber *section = [NSNumber numberWithInt:indexPath.row];
NSDictionary *infoDictionary = [NSDictionary dictionaryWithObject:section
forKey:#"CurrentTableView"]
NSString *UpdateTableView = #"UpdateTableView";
[[NSNotificationCenter defaultCenter] postNotificationName:UpdateTableView
object:self
userInfo:infoDictionary];
Now in A i'm listening like this
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(updateTableView:)
name:#"UpdateTableView"
object:nil];
which calls the method
#property (strong, nonatomic) NSNumber *section;
// :::: Some code here ::::
- (void)updateTableView:(NSNotification*)note
{
_section = [[note userInfo] valueForKey:#"CurrentTableView"];
NSLog(#"%d",[_section intValue]);
[self.tableView reloadData];
}
and the NSLog works fine, i mean it prints the right value.
I'm using _section to discriminate in the TableView delegate methods what kind of data to load.
The problem is that the call to this method (after the notification is received) happens BEFORE the view is actually reloaded (viewDidAppear and so) which set my #property _section to 0, in this way every time my TableView loads the data standing behind the [_section intValue] == 0.
How could i solve this? I need something that don't gets reset every time the view loads itself. Any suggestion?
EDIT: navigation controller to move from B to A
MenuNavigationController *navigationController = [self.storyboard instantiateViewControllerWithIdentifier:#"contentController"];
AViewController *homeViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"homeController"];
navigationController.viewControllers = #[homeViewController];
Do you really need NSNotification ? Notifications are used where you want to update a view, and by update i mean that the view is already created.
What i would do is fairly simple, in B i would set your NSNumber *section as an ivar (if you display controller A some place different from where you post you notification). When you posted your notification you would just instantiate your ivar.
Then A would have a similar variable and when you want to display A :
AViewController *homeViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"homeController"];
homeViewController.section = section;
navigationController.viewControllers = #[homeViewController];
Perhaps your property section isn't synthesizing to use your instance variable _section. Does your synthesize line look like this:
#synthesize section=_section;
Otherwise the compiler will implicitly create an instance variable name section
UPDATE
As #Justafinger mentioned, as of Xcode 4.4, the ivar will be named _section if you completely leave out the #synthesize line. If you do explicitly synthesize, however, and don't assign the ivar name in the #synthesize line the ivar name will default to section.

How do a ViewController knows it got focus on iOS? Like a "viewDidLoad"

I have a NavigationController and one of the tabs is supposed to load a ViewController.
This ViewController (1), when loaded on "viewDidLoad" does some stuff and then pushes a new ViewController (2). The thing is that after ViewController (1) has already passed through viewDidLoad, it won't pass through it again, unless the app is restarted.
Could you guys please refer a clever way to to this?
Here's what I am really doing:
- (void)viewDidLoad
{
// Keep track of cash using NSUserDefaults
BOOL dreceived[63];
int rightData;
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
//Load cash switches
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
NSData *data = [prefs objectForKey:#"dreceived"];
memcpy(&dreceived, data.bytes, data.length);
for(int n = 72; n >= 1; n = n - 1)
{
if(dreceived[n-1]==1)
{
rightData = n;
}
}
NSLog(#"Right Data %d", rightData);
CashItem *c = [cashflow objectAtIndex:rightData];
// Go for details
CashDetailedViewController *cdetail = [[[CashDetailedViewController alloc] init] autorelease];
cdetail.cash = c;
cdetail.navigationItem.hidesBackButton = YES;
[self.navigationController pushViewController:cdetail animated:YES];
}
The thing is, this code is never called again. And if I touch the tab twice, a blank view is displayed (th original xib view).
Thanks!
It sounds like you would want to use viewWillAppear. It is called every time that your view controller is about to be onscreen.
Although, based on what you've posted, you may want to rethink what your doing. Having a view controller that immediately presents another view controller should like it would lead to a confusing user experience.
Put your code in - (void)viewWillAppear instead
Try calling
[yourViewController.view setNeedsDisplay];
Or you could spin the code out to a seperate method and call it in viewDidLoad and viewDidAppear:animated

How to pass data to parent view IOS

I know this question is asked once every two days. I can not see what I am doing wrong though.
I have a storyboard navigation controller based app.
My notification and pop / push segues works well, only thing is I can not add string to parents view NSmutablearray.
I want to add a string object to parent view's nsmutablearray. My decent code does not pass any data.
parent.h
#interface CreaatePlistTableViewController : UITableViewController<UITableViewDelegate, UITableViewDataSource>{
NSMutableArray *presenterList;
}
#property (nonatomic, strong) NSMutableArray *presenterList;
parent.m
NSString * const NOTIF_CreatePlist_UpdateTableview= #"CreatePlist/UpdateTableview";
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Private interface definitions for update tableview
*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
#interface CreaatePlistTableViewController (private)
- (void)CreatePlistUpdateTableview:(NSNotification *)notif;
#end
#implementation CreaatePlistTableViewController
#synthesize presenterList=_presenterList;
- (void)viewDidLoad
{
[super viewDidLoad];
_presenterList=[[NSMutableArray alloc] init];
// Register observer to be called when logging out
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(CreatePlistUpdateTableview:)
name:NOTIF_CreatePlist_UpdateTableview object:nil];
NSLog(#"Presenter List: %#", _presenterList);
}
- (void)CreatePlistUpdateTableview:(NSNotification *)notif{
NSLog(#"Notification recieved");
NSLog(#"Presenter List: %#", _presenterList);
[_createPlistTableview reloadData];
}
child.h
#interface AddPresenterViewController : UITableViewController<UITextFieldDelegate,UIAlertViewDelegate>{
CreaatePlistTableViewController *crereaatePlistTableViewController;
}
#property(nonatomic,strong) CreaatePlistTableViewController *crereaatePlistTableViewController;
child.m
#synthesize crereaatePlistTableViewController=_crereaatePlistTableViewController;
//finished adding presenter
-(IBAction)finishedAddingPresenter:(id)sender{
//some xml string here
NSLog(#"final result XML:\n%#", writer.XMLString);
_crereaatePlistTableViewController=[[CreaatePlistTableViewController alloc]init];
//add object to parents view data source
[_crereaatePlistTableViewController.presenterList addObject:writer.XMLString];
//dismiss the view
[self.navigationController popViewControllerAnimated:YES];
//notify the parent view to update its tableview
[[NSNotificationCenter defaultCenter] postNotificationName:#"CreatePlist/UpdateTableview" object:nil];
}
Output
Notification recieved
Presenter List: (
)
So notification works when I click the button. But it does not pass object to nsmutablearray.
What I am doing wrong here ? How can I add an object to parent view's nsmutablearray?
It seems everything is good except your alloc of parent view object I am not that familiar with storyboard but You said you are using navigation navigation controller
so change this
_crereaatePlistTableViewController=[[CreaatePlistTableViewController alloc]init];
to
_crereaatePlistTableViewController= [self.navigationController.viewControllers objectAtIndex:0];
It may work I am not sure
You wrote this.
[_crereaatePlistTableViewController.presenterList addObject:writer.XMLString];
Do you ever initialize the array? No. Use the debugger and you will see that at this line the presenterList is nil.
Now as a point of style. Avoid using NSNotificationCenter to pass data or signaling other objects. #TheRonin gave a handy link. You should also look into some tutorials on Segues, because these are solved problems.
This is another related post that you might find interesting.

Detail View filled with plist information

I've been following a tutorial on iOS development - specifically drill-down UITableViews. I have my own custom plist established, but I can't seem to get the DetailViewController to populate with my plist information. I could really use some help here, I'm a bit over my head!
edit: Here's some details...
The app works through a plist-populated RootViewController, which is a UITableView. When there aren't any children left in the plist, it changes to a Detail view:
AppDelegate.m
NSDictionary *tempDict = [NSDictionary dictionaryWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"Data" ofType:#"plist"]];
self.data = tempDict;
RootViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
if(CurrentLevel == 0) { // At the 'root' of the plist
//Initilalize our table data source
NSArray *tempArray = [[NSArray alloc] init];
self.tableDataSource = tempArray;
AppDelegate *AppDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
self.tableDataSource = [AppDelegate.data objectForKey:#"Rows"];
self.navigationItem.title = #"PedalTome";
}
else
self.navigationItem.title = CurrentTitle;
}
later on...
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
//Get the dictionary of the selected data source.
NSDictionary *dictionary = [self.tableDataSource objectAtIndex:indexPath.row];
//Get the children of the present item.
NSArray *Children = [dictionary objectForKey:#"Children"];
if([Children count] == 0) {
DetailViewController *dvController = [[DetailViewController alloc] initWithNibName:#"DetailView" bundle:[NSBundle mainBundle]];
[self.navigationController pushViewController:dvController animated:YES];
}
else {
//Prepare to tableview.
RootViewController *rvController = [[RootViewController alloc] initWithNibName:#"RootViewController" bundle:[NSBundle mainBundle]];
//Increment the Current View
rvController.CurrentLevel += 1;
//Set the title;
rvController.CurrentTitle = [dictionary objectForKey:#"Title"];
//Push the new table view on the stack
[self.navigationController pushViewController:rvController animated:YES];
rvController.tableDataSource = Children;
}
}
My DetailViewController.m is empty, with the exception of a placeholder self.navigationController.title.
If I'm understanding correctly, I need to pass information from RootViewController to DetailViewController - the location and implementation of the plist, the index level (is that what it's called) in the plist, and the string inside that index level (under the key Detail).
At this point, any progress is amazing progress. Thanks in advance.
You can pass whatever information you need to your DetailViewController by setting up a synthesized property in your DetailViewController, and then passing your data to it inside your if-block.
For example, in your DetailViewController.h you would have the following (without ARC):
#property (retain, nonatomic) NSDictionary *myAwesomeDictionary;
Or, with ARC enabled:
#property (strong, nonatomic) NSDictionary *myAwesomeDictionary;
Then in DetailViewController.m you would have the following:
#synthesize myAwesomeDictionary;
Then you would change your code block to the following:
if([Children count] == 0) {
DetailViewController *dvController = [[DetailViewController alloc] initWithNibName:#"DetailView" bundle:[NSBundle mainBundle]];
[dvController setMyAwesomeDictionary:dictionary];
[self.navigationController pushViewController:dvController animated:YES];
}
This assumes that the NSDictionary called dictionary that you created a few lines above is the data that you'd like to show in your DetailViewController.
Then in your DetailViewController's viewDidLoad: method you can access that dictionary using self.myAwesomeDictionary and do whatever you need to do with it.
Disclaimer:
Two things seem to go against Apple's code style standards in your code:
Your AppDelegate stores your model (your plist). - Apple says that you shouldn't crowd your AppDelegate with global data/logic. In general, only write code that pertains specifically to a class, in that specific class.
You aren't parsing your plist into custom objects. - This makes it hard to code because you constantly have to figure out what your generic Array and Dictionary objects represent, and make your code totally unreadable for other people.
Some of your instance variable names are capitalized. For example, NSArray *Children should be NSArray *children and CurrentLevel should be currentLevel. Only Class names have the first letter capitalized.
Check out http://jlawr3nc3.github.com - specifically my CompanyRecords example code for information on how to make a class and FunWithArrays for how to parse a plist into custom objects. MusicLibraryiOS then delves into how to take a plist, parse it into custom objects, and then display it in a UITableView along with a detail view.
Table View Specifier May do what you need.
Specified Table View is an iOS table view that has its contents specified
via a plist file. Its purpose is largely demonstrative but is also designed
to be used in a live product (useful for credits pages). Can be used with
iOS version 4.2 and above.
A dig through their code will most likely be enlightening.

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