How are UITableView cells made to be able to be deleted by users?
A quick example would be:
// create a mutable array to manage your table data
NSMutableArray *tableList;
#property (nonatomic, retain) NSMutableArray *tableList;
in your viewDidLoad method you can initialize it with data (you should check if tableList is nil first though)
NSString *path = [[NSBundle mainBundle] pathForResource:#"TableData" ofType:#"plist"];
NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:path];
self.tableList = array;
[array release];
then in the implementation file, you implement this delegate method
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
NSUInteger row = [indexPath row];
[self.tableList removeObjectAtIndex:row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
you can then toggle editing mode via
[self.tableView setEditing:!self.tableView.editing animated:YES];
Take a look at the table view data source delegate method -tableView:commitEditingStyle:forRowAtIndexPath:.
You override this method in your table view delegate (usually your table view controller) and put your deletion logic here.
For example, you can call a UIAlertView to ask the user to confirm the deletion, or just manipulate the data model directly, removing the object from your table view's data source.
Related
I am facing a crashing problem in cellForRowAtIndexPath tableview delegate method
#interface EventListView : UIViewController <UITableViewDelegate, UITableViewDataSource>
IBOutlet UITableView *tblView;
NSMutableArray *arr_EventValues,*arr_Event_Details;
NSMutableArray *arr_EventListDetails;
#property(nonatomic, retain)NSMutableArray *arr_EventValues,*arr_EventListDetails, *arr_Event_Details;
#property(nonatomic, retain)UITableView *tblView;
- (void)viewDidLoad
{
appdelegate = (VibesGuideAppDelegate *)[[UIApplication sharedApplication] delegate];
ViewCalendar = [[CalendarView alloc] initWithNibName:#"CalendarView" bundle:[NSBundle mainBundle]];
[self.navigationController.navigationBar setHidden:YES];
self.arr_Event_Details = [[NSMutableArray alloc] init];
self.arr_EventValues = [[NSMutableArray alloc] init];
[super viewDidLoad];
}
// Customize the number of sections in the table view.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if ([self.arr_EventListDetails count] > 0)
{
return [self.arr_EventListDetails count];
}
return 0;
}
-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
// ------------------------------- Custom cell ------------------------------
Customcell *cell = (Customcell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
cell = [[[Customcell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
cell.textLabel.text = #"Hello";
return cell;
}
* -[EventListView tableView:cellForRowAtIndexPath:]: message sent to deallocated instance 0x60e01b0 and I used tableview from xib and set all connections and also got arrayvalues in numberOfRowsInSection in method but in cellForRowAtIndexPath method is not called so please give me idea my issue....
Thanks in advance.
At first it seems your some variable gets released. Make sure you have properly allocated it. If you have declared #property for it you better use the variable as self.variable. You can use retain and in case of IOS 5 strong in property declaration.
Just to be sure you can track if any variable gets released via setting NSZombieEnabled to YES. With zombies enabled, messages to deallocated objects will no longer behave strangely or crash in difficult-to-understand ways, but will instead log a message and die in a predictable and debugger-breakpointable way. You can set NSZombieEnabled by the following steps.
Select Product from the menu bar above. Keep alt/option pressed and select "Test..." or "Run...". Go to the Arguments tab, and add NSZombieEnabled YES in the "Environment Variables" section.
Your tableview itself is already released - the error message says that you send the cellForRowAtIndexPath message to a deallocated instance of the table view - so your problem lies somewhere in not retaining or releasing the EventListView and cannot be seen in the code displayed here.
Check this one:
Table DataSource and delegate is set or not.
Used array in cellForRowAtIndexPath is properly set with property and synthesized as well used with self. name.
First of all you dequeue the cell and then create a new one. This is not a good practice, if you are able to dequeue a cell you should not create a new one. You should have something like this:
Customcell *cell = (Customcell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil)
{
cell = [[[Customcell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
}
fix this and let me know if you are still running on the same problem.
I am trying to feed in some JSON data to my iPhone app, the data is coming in fine as I have NSLog's telling me so.
The problem I am having is trying to get the results to show in a UITableView. I have a navigation controller underneath a tab bar controller, the navigation controller contains a table view controller which loads another NIB file with a table view connected to a class which is the delegate and data source delegate.
I also need to categorize the results into sections - these being
England
Scotland
Wales
N.Ireland
To get an idea of what JSON string I am using see this one.
As you can see the JSON does not cater for the sections but I am yet to implement this, so i would need to know beforehand so I do not have to amend much code later on.
OK - I am using Stig JSON parser.
Here is my ListVenuesView.h (connected to table view)
#import <UIKit/UIKit.h>
#import "SBJson.h"
#interface ListVenuesView : UITableViewController <UITableViewDelegate, UITableViewDataSource> {
IBOutlet UITableView *venueList;
NSMutableDictionary *jsonArray;
}
#property (nonatomic, retain) IBOutlet UITableView *venueList;
#property (nonatomic, retain) NSMutableDictionary *jsonArray;
#end
jsonArray is used to store the JSON data and eventually the proper array.
And here is my ListVenuesView.m (key areas in question)
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(#"Table View Loaded");
// Uncomment the following line to preserve selection between presentations.
// self.clearsSelectionOnViewWillAppear = NO;
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem;
// This is where we load the JSON data
NSURL *jsonURL = [NSURL URLWithString:#"http://www.thebigfishexperience.org.uk/sources/ajax/venue-json.php?location=peterborough"];
NSString *jsonData = [[NSString alloc] initWithContentsOfURL:jsonURL];
NSLog(#"%#", jsonData);
// Convert jsonData to array
self.jsonArray = [jsonData JSONValue];
NSLog(#"%#", jsonArray);
NSLog(#"count is: %i", [self.jsonArray count]);
// Release NSString and NSURL
[jsonURL release];
[jsonData release];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [self.jsonArray count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
NSMutableDictionary *dict = [self.jsonArray objectAtIndex: indexPath.row];
cell.textLabel.font = [UIFont fontWithName:#"Arial" size:15.0];
cell.textLabel.text = [dict objectForKey:#"venueName"];
cell.detailTextLabel.text = [dict objectForKey:#"venueCordDist"];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
// Configure the cell...
return cell;
Also how can I use the data in the cells to go to another subview of the nav controller which gives me a back button and displays the info from the JSON string just for that particular cell that has been tapped.
I think this has something to do with it? Not sure though as this is my first app i am building! So probably expect more pleas of assistance - ha ! ;)
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// Navigation logic may go here. Create and push another view controller.
/*
DetailViewController *detailViewController = [[DetailViewController alloc] initWithNibName:#"Nib name" bundle:nil];
// ...
// Pass the selected object to the new view controller.
[self.navigationController pushViewController:detailViewController animated:YES];
[detailViewController release];
*/
}
On selecting a row, as mentioned by u, we are navigating to another view. Let us assume that the view controller is DetailViewController which is a sub-class of UIViewController.
In the DetailViewController.h , declare a NSDictionary object.
In DetailViewController.m, add
-(void)setVenueDict:(NSDictionary*)venueDict
{
if( _venueDict )
{
[_venueDict release];
}
_venueDict = [venueDict retain];
}
In ParentViewController, ur didSelectRow.. method should be like this.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// Navigation logic may go here. Create and push another view controller.
DetailViewController *detailViewController = [[DetailViewController alloc] initWithNibName:#"Nib name" bundle:nil];
// ...
// Pass the selected object to the new view controller.
NSDictionary *dict = [self.jsonArray objectAtIndex: indexPath.row];
[detailViewController setVenueDict:dict];
detailViewController.title = [dict objectForKey:#"venueName"];
[self.navigationController pushViewController:detailViewController animated:YES];
[detailViewController release];
}
In the second view controller, u can do whatever u want with the _venueDict.
Nathan,
since you want to reuse the data parsed from the JSON feed over more than one ViewController the best way to approach this is to build an object Model so that you can pass the object for the selected row in the list to the detail ViewController.
I would also separate the JSON parsing code into a separate class and not keep it in the ViewController.
You can find classes to fetch JSON on this link.
The result from the custom code to parse the JSON feed would give back a NSDictionary with as keys the section names you mention. And the value in the NSDictionary for those keys would be an array of your custom objects that contain all the relevant data for one row (and detail screen).
Hope this helps you on your way.
jsonArray is NSMutableDictionary.
have to use
[jsonArray objectForKey:key];
//check this line
NSMutableDictionary *dict = [self.jsonArray objectAtIndex: indexPath.row];
this may help.
I am trying to refresh an UITableView every time I navigate the the view that contains this Table.
I Have a ViewController and a custom UITableViewController that manages to set the Table Correctly when the application starts, using an NSMutableArray contained inside the controller.
When I navigate to the page containing the table, the ViewController calls a function that gets the data from a server with an HTTP request and parse it in an NSMutableArray.
Now here is my problem. I manage to send this array to my UITableViewController, but when I want to refresh my tableView, nothing happens.
I tried to use [myTable reloadData], but it doesn't calls the numberOfRowsInSection, or cellForRowAtIndexPath functions. I saw that people with the same problem solved it using [self.myTable ReloadData], but I get an error :
accessing unknown getter/setter method
I am pretty new to objective-C, and this error is still a bit mysterious to me as I get it a bit randomly.
Anyway, there is a high probability that I made a mess with the declaration of the UITableViewController (where am I supposed to declare it?) and with the Interface Builder links, so this can be a clue to find the solution.
Any one have an idea?
Thank you very much!
EDIT : Here is my tableview controller class:
#import "MyCell.h"
#class Mycell;
#interface MyTableController : UITableViewController {
IBOutlet MyCell * myCell;
IBOutlet UITableView * myTable;
NSMutableArray *data;
}
#property (nonatomic, retain) IBOutlet UITableView * myTable;
- (void) EditTable : (NSMutableArray*) param;
#end
And now the .m:
#implementation MyTableController
#synthesize myTable;
- (void) viewDidLoad {
[super viewDidLoad];
myTable = [[UITableView alloc] init];
data = [[NSMutableArray alloc] init];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [data count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"MyCell";
MyCell *cell = (MyCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; >
if (cell == nil) {
NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:#"MyCell" owner:self options:nil];
for (id currentObject in topLevelObjects){
if ([currentObject isKindOfClass:[UITableViewCell class]]){
cell = (MyCell *) currentObject;
}
}
}
NSString *datastring = [listenom objectAtIndex:indexPath.row];
[cell setCell: datastring ];
return cell;
}
- (void) EditTable : (NSMutableArray*) param{
//This function is called by the ViewController when the user goes to the page containing the view
data = param; //The param array contains the data from the HTTP request
[self.tableView reloadData];
[self.myTable reloadData]; //I tried both, but only the first one actually calls the previous functions
}
You have a number of problems in this code sample. I'll point out a few of them here but I highly recommend reading the relevant Apple documentation at:
http://developer.apple.com/library/ios/#featuredarticles/ViewControllerPGforiPhoneOS/Introduction/Introduction.html
and
http://developer.apple.com/library/ios/#documentation/userexperience/conceptual/TableView_iPhone/AboutTableViewsiPhone/AboutTableViewsiPhone.html
Some issues in your code:
Since the class MyTableController is a subclass of UITableViewController you don't need the attribute and property for myTableView. The tableView property is defined and initialized as part of UITableViewController's implementation with its dataSource and delegate set to the UITableViewController instance. This is why [self.tableView reloadData] is calling your delegate and dataSource protocol methods.
You are also using interface builder so if you did want to create your own subviews you should either do that within IB and set the outlet there or do it in your code which means creating the subview(s) in viewDidLoad and then adding them to your view with [view addSubview:mySubView].
A better way to set the data for your table would be to create a property for your data attribute and call setData from the view controller that has initialized the MyTableController instance. You would use the setData: method to do this. You can call [self.tableView reloadData] in setData. You don't need to explicitly reload the table when the view is loaded as this is done automatically. A more minor point, if you stay with EditTable I would rename it to be more descriptive and to use camel case (e.g. setDataForTable`) to be consistent with iOS conventions.
You don't show any init/alloc for the listenom attribute referenced in tableView:cellForRowAtIndexPath:. Did you mean to use data instead?
Is your MyTableController.m file the complete version? If so, you are missing viewDidUnload and dealloc methods. Both of which are required. viewDidUnload should release any objects allocated in viewDidLoad and dealloc should release anything retained by the controller (including objects released in viewDidUnload.
As you are using tableViewController you should be able to use self.tableView instead to reload the data like this
[self.tableView reloadData];
you need to synthesize first then you can use self.myTable
do on the top
#synthesize myTable
and then
[self.myTable reloadData];
i have tryed to display my NSMutableArray in a Table View by following a tutorial. It has completley failed for some reason, i think i have a good idea why but cannot get around it, this is my code:
- (void) scoreSystem {
scoreArray = [[NSMutableArray alloc] init];
NSNumber *onescore = [NSNumber numberWithInteger:score];
[scoreArray addObject:onescore];
NSNumber *twoscore = [NSNumber numberWithInteger:score];
[scoreArray addObject:twoscore];
NSNumber *threescore = [NSNumber numberWithInteger:score];
[scoreArray addObject:threescore];
NSNumber *fourscore = [NSNumber numberWithInteger:score];
[scoreArray addObject:fourscore];
NSNumber *fivescore = [NSNumber numberWithInteger:score];
[scoreArray addObject:fivescore];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [scoreArray count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
cell.textLabel.text = [scoreArray objectAtIndex:indexPath.row];
return cell;
}
I think it is because it wont let me link up everything properly in IB, it lets me put the data source and delegate to the Files owner, but then when i drag from the files owner to my view it says 'delegate' instead of 'view', i think its because i am doing it in the 'main window' not VC.
Is there any way round this?
Thanks!
harry.
You want to set the class that your code is in as the tableview's datasource. Create an instance of your class in IB (use the NSObject, and rename its class to YourClass).
This will create an instance of your class that will be available when the nib is decoded.
Then, control-drag from the tableview to your class, and set the datasource.
That's it! You should be able to set breakpoints in your -numberOfRowsInSection: method above, and see it called as soon as the table view comes in view. If you don't, check your connections and check for typos: the runtime is case-sensitive.
Well for some reason someone bumped this old thread. I might as well chime in. The reason this code has problems is because it is trying to set the text property of the cell to a NSNumber.
cell.textLabel.text = [scoreArray objectAtIndex:indexPath.row];
Try this instead:
cell.textLabel.text = [[scoreArray objectAtIndex:indexPath.row] stringValue];
In the following bit of code, I'm setting the table view cell text with a value from the NSMutableArray 'categories' which is a property of my view controller. That works fine.
But when I try the exact same code in another method, it crashes (it compiles without errors or warnings). If I change the following line in the didSelectRowAtIndexPath method:
NSString *categoryName = [categories objectAtIndex:indexPath.row];
to
NSString *categoryName = [[NSString alloc] initWithString:#"test"];
It works... any ideas?
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell.
NSString *categoryName = [categories objectAtIndex:indexPath.row];
cell.textLabel.text = categoryName;
return cell;
}
// Override to support row selection in the table view.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
printf("User selected row %d\n", [indexPath row] + 1);
ButtonsPageViewController *bView = [ButtonsPageViewController alloc];
NSLog(#"created instance of buttonspageviewcontroller");
NSString *categoryName = [categories objectAtIndex:indexPath.row];
NSLog(#"category name set");
bView.selectedCategory = categoryName;
NSLog(#"selected category property set");
[self.navigationController pushViewController:bView animated:YES];
NSLog(#"push view controller");
[bView release];
}
The difference between
NSString *categoryName = [categories objectAtIndex:indexPath.row];
and
NSString *categoryName = [[NSString alloc] initWithString:#"test"];
Is that the first line copies a pointer to the object (retain count does not change) whereas the second one creates a new object (retain count = 1).
In cellForRowAtIndexPath, when you set the text property, it copies or retains the string, so you're fine. In didSelectRowAtIndexPath you are setting a property of ButtonsPageViewController, which I assume is your own code, but perhaps it is not copying or retaining the object.
Also, the line
ButtonsPageViewController *bView = [ButtonsPageViewController alloc];
is going to lead to problems. You need to call init to properly initialize the object. All you've done in that line is allocate memory for it.
In general, it looks like you need to brush up on Retain/Release memory management. That should save you some trouble.
Like benzado says, it's an issue retaining the selectedCategory value in ButtonsPageViewController.
Are you using #property and #synthesize or are you writing your own accessors? If it's the former, you probably need to look at the property declaration attributes. Otherwise, it's probably a retain/release thing in your custom accessor.
The Declared Properties section of The Objective-C 2.0 Programming Laungauge is a good resource for rules of declaring synthesized accessors.