Update selection from second UITableView in original UITableView - iphone

Question

I can't get my first UITableView to update with a setting made in a second UITableView.
A user clicks a row in firstTableView causing secondTableView to be displayed. When the user selects a row, secondTableView disappears and firstTableView is reappears. However, the data isn't updated.
I tried using the following in firstTableView:
- (void) viewWillAppear:(BOOL)animated {
// (verified it's defenitely section 2, row 0 by logging it before and after...)
// (also verified that the source data has been updated before viewWillAppear is called...)
NSIndexPath *durPath = [NSIndexPath indexPathForRow:0 inSection:2];
NSArray *paths = [NSArray arrayWithObject:durPath];
[self.firstTableView reloadRowsAtIndexPaths:paths withRowAnimation:UITableViewRowAnimationNone];
// If I use some row animation, I can clearly see that the correct row is being animated, it's just not being updated.
}
But the label does not update. Obviously I'm missing something.
Both views are modal view controllers.
Here's my cell construction:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [firstTableView dequeueReusableCellWithIdentifier:CellIdentifier];
UILabel *myLabel = [[UILabel alloc] initWithFrame:CGRectMake(150.0, 15.0, 120.0, 17.0)];
myLabel.backgroundColor = [UIColor clearColor];
myLabel.font = [UIFont systemFontOfSize:14];
myLabel.textAlignment = UITextAlignmentLeft;
static NSString* kConstants[] = {kOption0,kOption1,kOption2,kOption3,kOption4,kOption5,kOption6,kOption7,kOption8,kOption9,kOption10,nil};
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle: UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
if (indexPath.section == 2) {
[cell addSubview:myLabel];
}
}
switch (indexPath.section) {
case 0:
// … deal with a bunch of UISwitches
break;
case 1:
// … deal with section 1 stuff
break;
case 2:
{
NSLog(#"Verify that intType has in fact been changed here: %i, %#",intType, kConstants[intType]);
// Even though intType and the constant string reflects the correct (updated) values when returning from secondTableView, myLabel.text does not change, ie: it's correct one line above, but not correct one line below. The myLabel.text is just not updating to the new value.
myLabel.text = kConstants[intType];
cell.textLabel.text = #"Choose Some Value:";
cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
}
break;
case 3:
// … deal with section 3 stuff
break;
}
[myLabel release];
return cell;
}

Answer 1

I have finally found the problem: when you reload the cell, (cell == nil) will be false, since the cell is already present.
Also, even if (cell == nil) is true, you are adding a new subview, and not modifying the existing one -- which is not only a memory management problem, it also makes the text unreadable by placing the labels on top of each other.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
static NSString* kConstants[] = {kOption0,kOption1,kOption2,kOption3,kOption4,kOption5,kOption6,kOption7,kOption8,kOption9,kOption10,nil};
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle: UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
UILabel *myLabel = [[UILabel alloc] initWithFrame:CGRectMake(150.0, 15.0, 120.0, 17.0)];
myLabel.backgroundColor = [UIColor clearColor];
myLabel.font = [UIFont systemFontOfSize:14];
myLabel.textAlignment = UITextAlignmentLeft;
myLabel.tag = 1;
myLabel.text = kConstants[intType];
[cell addSubview:myLabel];
[myLabel release];
cell.textLabel.text = #"Label";
cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
} else {
UILabel *myLabel = (UILabel *)[cell viewWithTag:1];
myLabel.text = kConstants[intType];
}
return cell;
}

Answer 2

For anyone who stumbles upon this in the future, I'm posting a complete solution to my question here, thanks especially to Antal for showing me the major error in my table construction.
Using ViewWillAppear to reload the table is a bad idea in general, because it causes the table, or portions of the table to load twice. The proper way to do this is using the Delegate method of the second view controller, which I've done here.
I'm posting the relevant portions of the two view controllers. Both are setup as UViewControllers, not as UITableViewControllers. Both are modal views.
I hope someone finds this useful.
//
// FirstViewController.h
//
#import <UIKit/UIKit.h>
#import "SecondViewController.h"
#interface FirstViewController : UIViewController
<SecondViewControllerDelegate, UITableViewDataSource, UITableViewDelegate>
{
UITableView *firstTableView;
NSArray *myArray;
}
#property (nonatomic, retain) IBOutlet UITableView *firstTableView;
#property (nonatomic, assign) NSArray *myArray;
- (void) didSelectOptions:(NSInteger *)intOptionType;
- (void) didCancelOptions;
#end
//
// FirstViewController.m
//
#import "FirstViewController.h"
#import "Constants.h"
#implementation FirstViewController
#synthesize firstTableView;
#synthesize myArray;
- (void) viewDidLoad {
// Load the array that contains the option names, in this case, constants stored in Constants.h
myArray = [[NSArray alloc] initWithObjects:kStoredRowName0, kStoredRowName1, kStoredRowName2, nil];
}
// do everything else to deal with the first view . . .
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// Use the indexPath.section as the identifier since objects in each section share unique construction, ie: switches, etc.
NSString *identifier = [NSString stringWithFormat: #"%d", [indexPath indexAtPosition: 0]];
// In this example I'm storing the important integer value in NSUserDefaults as kStoredConstant
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
UITableViewCell *cell = [firstTableView dequeueReusableCellWithIdentifier:identifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc]
initWithStyle: UITableViewCellStyleDefault
reuseIdentifier:identifier]
autorelease];
switch (indexPath.section) {
case 0: // OnOff Controls using UISwitch
NSLog(#"Section 0");
// set up switches …
break;
case 1: // Segmented Controls using UISegmentedControl
NSLog(#"Section 1");
// set up segmented controls …
break;
case 2: // Label that will be selected from SecondViewContoller
NSLog(#"Section 2");
// set up label
UILabel *myLabel = [[UILabel alloc] initWithFrame:CGRectMake(150.0, 15.0, 120.0, 17.0)];
myLabel.backgroundColor = [UIColor clearColor];
myLabel.font = [UIFont systemFontOfSize:14];
myLabel.textColor = [UIColor colorWithRed:0.25 green:0.0 blue:0.0 alpha:1.0];
myLabel.textAlignment = UITextAlignmentLeft;
myLabel.tag = indexPath.section;
myLabel.text = [myArray objectAtIndex:[userDefaults integerForKey:kStoredConstant]];
[cell addSubview:myLabel];
[myLabel release];
cell.textLabel.text = #"Choose A Value:";
cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
break;
}
} else {
switch (indexPath.section) {
case 0: // OnOff Controls using UISwitch
NSLog(#"Section 0");
break;
case 1: // Segmented Controls using UISegmentedControl
NSLog(#"Section 1");
break;
case 2: // Label that will be selected from SecondViewContoller
{
NSLog(#"Section 2");
UILabel *myLabel = (UILabel *)[cell viewWithTag:indexPath.section];
myLabel.text = [myArray objectAtIndex:[userDefaults integerForKey:kStoredConstant]];
}
break;
}
}
// Format the cell label properties for all cells
cell.textLabel.backgroundColor = [UIColor clearColor];
cell.textLabel.font = [UIFont systemFontOfSize:14];
cell.textLabel.textColor = [UIColor colorWithRed:0.25 green:0.0 blue:0.0 alpha:1.0];
cell.textLabel.highlightedTextColor = [UIColor colorWithRed:1.0 green:1.0 blue:0.9 alpha:1.0];
return cell;
}
- (void) tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath {
// Un-highlight the selected cell
[firstTableView deselectRowAtIndexPath:indexPath animated:YES];
switch (indexPath.section) {
case 0: // Deal with changes in UISwitch Controls
NSLog(#"Section 0");
break;
case 1: // Deal with changes in Segmented Controls
NSLog(#"Section 1");
break;
case 2: // Launch the SecondViewContoller to select a value
{
SecondViewController *secondViewController = [[SecondViewController alloc] init];
secondViewController.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
secondViewController.secondViewControllerDelegate = self;
[self presentModalViewController:secondViewController animated:YES];
[secondViewController release];
}
break;
}
}
#pragma mark -
#pragma mark SecondViewControllerDelegate
- (void) didSelectOptions:(NSInteger *)intOptionType {
// User selected a row in secondTableView on SecondViewController, store it in NSUserDefaults
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults setInteger:(int)intOptionType forKey:kStoredConstant];
[userDefaults synchronize];
// Reload only the row in firstTableView that has been changed, in this case, row 0 in section 2
[self.firstTableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:0 inSection:2]]withRowAnimation:UITableViewRowAnimationNone];
[self dismissModalViewControllerAnimated:YES];
}
- (void) didCancelOptions {
// User didn't select a row, instead clicked a done or cancel button on SecondViewController
[self dismissModalViewControllerAnimated:YES];
}
// Make sure and release Array and Table
//
// SecondViewController.h
//
#import <UIKit/UIKit.h>
#protocol SecondViewControllerDelegate <NSObject>
- (void) didCancelOptions;
- (void) didSelectOptions:(NSInteger *)optionType;
#end
#interface SecondViewController : UIViewController
<UITableViewDataSource, UITableViewDelegate>
{
NSArray *myArray;
UITableView *secondTableView;
id secondViewControllerDelegate;
}
#property (nonatomic, retain) NSArray *myArray;
#property (nonatomic, retain) IBOutlet UITableView *secondTableView;
#property (nonatomic, assign) id<SecondViewControllerDelegate> secondViewControllerDelegate;
- (IBAction) doneViewingOptions:(id)sender; // This is wired to a Cancel or a Done Button
#end
//
// SecondViewController.m
//
#import "SecondViewController.h"
#import "Constants.h"
#implementation SecondViewController
#synthesize secondViewControllerDelegate;
#synthesize myArray;
#synthesize secondTableView;
- (void) viewDidLoad {
// Load the array that contains the option names, in this case, constants stored in Constants.h
myArray = [[NSArray alloc] initWithObjects:kStoredRowName0, kStoredRowName1, kStoredRowName2, nil];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// Build a default table. This one is simple so the following is the only important part:
cell.textLabel.text = [myArray objectAtIndex:indexPath.row];
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// Return the changed row value to the FirstViewController using secondViewControllerDelegate
[self.secondViewControllerDelegate didSelectOptions:(NSInteger *)indexPath.row];
}
- (IBAction) doneViewingOptions:(id)sender {
// User didn't select a row, just clicked Done or Cancel button
[self.secondViewControllerDelegate didCancelOptions];
}
// Make sure and release Array and Table

Answer 3

You can use reloadRowsAtIndexPaths to reload a specific row (or rows) and avoid having to reload the entire table.
As for the label that displays the string value, could you post the code so we can see?