UITableView reloadData doesn't work when change sub object in datasoure. - ios

Question

There are 5 objects in datasoure for example,if the first object is like this:
Obj -> id:1,name:"A"
when I change the object's name to "B";
Obj -> id:1,name:"B"
then [tableView reloadData]
the first cell still display "A",I want to change it to "B".

Answer 1

In the cellForRowAtIndexpath method manage the datasource method properly as it retrives the value from the datasource array and displays it,That is it
I doubt the problem is that the reusability is causing the trouble in your code
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell;
static NSString *cellIdentifier1 = #"surveyCell";
if (tableView== self.surveytableView) {
cell= [tableView dequeueReusableCellWithIdentifier:cellIdentifier1];
if(cell==nil)
{
//alloc the cell
//DO NOT SET THE VALUE HERE
}
//here set the value
return cell;
}

Answer 2

here is the code, what i did was,
created a class called "DataClass" which provides data for your tableview
created objects like you mentioned , i stored it in an array("dataSource")
after that i loaded it to tableview (i assume u are properly wired up tableview datasource and delegate)
I put a button to make change the string in the datasource array.
button's action is connected to method and within that i am reloading the tableview
//class DataClass
#interface DataClass : NSObject
{
#public;
NSString *str;
}
#implementation DataClass
- (id)init
{
[super init];
str = nil;
return self;
}
#end
//viewController.h
#interface ViewController : UIViewController<UITableViewDataSource ,UITableViewDelegate>
{
IBOutlet UITableView *aTableView;
IBOutlet UIButton *aButton;
}
- (IBAction)whenButtonClicked:(id)sender;
#end
//in .m file
#import "ViewController.h"
#import "DataClass.h"
#interface ViewController ()
{
NSMutableArray *DataSource;
}
#end
// ViewController.m
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
aTableView.dataSource = self;
aTableView.delegate = self;
DataSource = [[NSMutableArray alloc]init];
for(int i=0 ; i<5 ; i++)
{
DataClass *data = [[DataClass alloc]init];
data->str=#"hello";
[DataSource addObject:data];
[data release];
}
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *aCell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
if(aCell == nil)
{
aCell = [[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"Cell"]autorelease];
}
DataClass *aValue = [DataSource objectAtIndex:indexPath.row];
aCell.textLabel.text = aValue->str;
return aCell;
}
- (IBAction)whenButtonClicked:(id)sender
{
DataClass *aObj = [DataSource objectAtIndex:2];//changing the 3'rd object value as yours in 5th object
aObj->str = #"world";
[aTableView reloadData];
}
#end
//after "changeValue" button pressed the third row displays "world"