Dynamically Changing UITableView's Contents - iphone

Question

I have an NSURL object which gets data from my site, based on a variable entered by the user into the search bar.
I split this data into an NSArray.
Once I have done that I wish to display the data in a UITableView.
My question is this. Is it possible to load the data into a UITableView dynamically?
i.e. Program loads, no data so UITableView is empty, then the user searches for one variable. Gets some data and the contents is loaded into the UITableView. Searches for a new variable, old data is cleared from UITableView and the new data is added?
I'm currently trying to do this using interface builder, but fear that I may have to make my interface pragmatically, so that I could destroy and re-create the UITableView, but i'm, not sure.
Thanks for any help.

Answer 1

Sure the method reloadData on UITableView will do the trick

Answer 2

Fear not, subclassing UITableView is very easy. In xCode simply choose new file, choose "Cocoa Touch Classes", "Objective-c class" and in the "Subclass of" dropdown pick "UITableView". xCode will add a UITableViewController subclass complete with stubs to build on.
I filled in a very simple example that draws the table data from an array and is displayed from the Application Delegate. As you suggested sending a reloadData message to the UITableView will refresh the displayed data.
As you probably found out, using InterfaceBuilder for this job is a lot harder than doing it programatically.
Cheers, niels
//
// MyTableViewController.m
// TableView
//
// Created by Niels Castle on 7/15/09.
// Copyright 2009 Castle Andersen ApS. All rights reserved.
//
#import "MyTableViewController.h"
#implementation MyTableViewController
// Initializer do custom initialisation here
- (id)initWithStyle:(UITableViewStyle)style {
if (self = [super initWithStyle:style]) {
// This is the source of my data. The simplest source possible,
// an NSMutableArray, of name. This would be the data from your web site
array = [[NSMutableArray alloc]
initWithObjects:#"Niels", #"Camilla", #"William", nil];
}
return self;
}
// How many section do we want in our table
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
// Customize the number of rows in the table view
// Simply the number of elements in our array of names
- (NSInteger)tableView:(UITableView *)tableView
numberOfRowsInSection:(NSInteger)section {
return [array count];
}
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// Reuse cells
static NSString *id = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:id];
if (cell == nil) {
cell = [[[UITableViewCell alloc]
initWithStyle: UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier] autorelease];
}
// Simplest possible cell - displaying a name from our name array
[[cell textLabel] setText: [array objectAtIndex:[indexPath row]]];
return cell;
}
- (void)dealloc {
[super dealloc];
[array release];
}
#end
//
// TableViewAppDelegate.m
// TableView
//
// Created by Niels Castle on 7/15/09.
// Copyright Castle Andersen ApS 2009. All rights reserved.
//
#import "TableViewAppDelegate.h"
#import "MyTableViewController.h"
#implementation TableViewAppDelegate
#synthesize window;
- (void)applicationDidFinishLaunching:(UIApplication *)application {
MyTableViewController *twc = [[MyTableViewController alloc]
initWithStyle: UITableViewStylePlain];
[window addSubview: [twc view]];
[window makeKeyAndVisible];
}
- (void)dealloc {
[window release];
[super dealloc];
}
#end

Answer 3

It's a bit complicated, but my solution that is working very reliably is following:
(assume that you have an array as bunch of arrays, that each represents a section and contains items that are in fact rows in table).
This example fits at the situation, when we load some data from server (e.g. JSON), and the result can be very different in number of sections and/or rows.
void function, you can omit it
-(void)addToPropertiesTable {
//fullTableData is above mentioned two dimensional array
int sectionsCount = _fullTableData.count;
int count = 0;
NSMutableArray *insertIndexPaths = [NSMutableArray array];
NSMutableArray *deleteIndexPaths = [NSMutableArray array];
for(int j = 0; j < sectionsCount; j++) {
NSMutableArray *currentAdverts = [[NSMutableArray alloc] init];
[currentAdverts addObjectsFromArray:[_fullTableData objectAtIndex:j]];
count = [currentAdverts count];
int currentRowsInSection = [self.propertiesTable numberOfRowsInSection:j];
if(currentRowsInSection > 0) {
//if any data in current tableView, lets get rid of them first
for (int i = [self.propertiesTable numberOfRowsInSection:j] - 1; i >=0 ; i--)
{
[deleteIndexPaths addObject:[NSIndexPath indexPathForRow:i inSection:j]];
}
}
for (NSUInteger item = 0; item < count; item++) {
[insertIndexPaths addObject:[NSIndexPath indexPathForRow:item inSection:j]];
}
}
[self.propertiesTable beginUpdates];
//we delete old rows - whether we need them or not
[self.propertiesTable deleteRowsAtIndexPaths:deleteIndexPaths
withRowAnimation:UITableViewRowAnimationFade];
if([self.propertiesTable numberOfSections]) {
//if any sections, we remove them
NSIndexSet *nsIndexSetToDelete = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0,[self.propertiesTable numberOfSections])];
[self.propertiesTable deleteSections:nsIndexSetToDelete withRowAnimation:UITableViewRowAnimationAutomatic];
}
//here we have to set new sections, whether they have changed or not
NSIndexSet *nsIndexSetToInsert = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0,sectionsCount)];
[self.propertiesTable insertSections:nsIndexSetToInsert withRowAnimation:UITableViewRowAnimationAutomatic];
//finally we insert rows
[self.propertiesTable insertRowsAtIndexPaths:insertIndexPaths
withRowAnimation:UITableViewRowAnimationFade];
[self.propertiesTable endUpdates];
//now we see the change in UI
[self.propertiesTable reloadData];
}