How do I drill down through a plist using UITableViews? - ios

Question

I'm wanting to drill down through a plist using uitableviews to get the a specific school. The drill down goes state->district->school. I've created a plist, but am not 100% sure that the structure is the best. Also, I can get the first set of information active on the first tableview, but am not sure how to proceed from there. Will I need to create a tableview for each drill down(stateview, districtview, schoolview) or can I reuse a generic tableview since they will simple be lists? Below is what I have so far. Thanks for your help.
PLIST
<plist version="1.0">
<array>
<dict>
<key>districts</key>
<dict>
<key>District 1</key>
<array>
<string>School 2</string>
<string>School 1</string>
</array>
<key>District 2</key>
<array>
<string>School 3</string>
<string>School 4</string>
</array>
</dict>
<key>state</key>
<string>South Dakota</string>
</dict>
<dict>
<key>districts</key>
<array>
<string>District 1</string>
<string>District 2</string>
</array>
<key>state</key>
<string>Arkansas</string>
</dict>
<dict>
<key>districts</key>
<array>
<string>District 3</string>
<string>District 4</string>
</array>
<key>state</key>
<string>New York</string>
</dict>
</array>
</plist>
And here is my viewcontroller
#import "plistViewController.h"
#interface plistViewController ()
#end
#implementation plistViewController
- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
}
return self;
}
#synthesize content = _content;
-(NSArray *)content
{
if (!_content) {
_content = [[NSArray alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"Data" ofType:#"plist"]];
}
return _content;
}
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
#pragma mark - Table view data source
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [self.content count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
cell.textLabel.text = [[self.content objectAtIndex:indexPath.row] valueForKey:#"state"];
return cell;
}
#pragma mark - Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// Navigation logic may go here. Create and push another view controller.
}
#end

Answer 1

The best thing about UITableView is that it doesn't care what data it displays. It just asks its delegate a few different questions:
How many sections should I have?
How many rows will be in each section?
May I have a UITableViewCell for this _ Index Path?
So, you have to focus on making your delegate responses provide the correct data.
So, first split your plist up into manageable chunks. The UITableView prima-donna dataSource is an NSArray. Neatly maps to tableViews because of indexing logic.
That said, your first tableViewController plistViewController has good logic for displaying info. Specifically, you are querying the NSDictionary at array position x and asking for it to return its state object. 3 Dictionary objects, 3 strings returned. Nice.
So how do you go to the next level? Your tableView will help you here. It asks a specific question of its delegate:
What do I do when user touches Section Y Row X?
You're going to need to set up another UITableViewController subclass called DistrictViewController. In the header .h file, you are going to need to make a strong property to an NSDictionary object. like so:
//DistrictViewController.h
#interface DistrictViewController : UITableViewController
#property (nonatomic, strong) NSDictionary *districtDictionary;
#end
//DistrictViewController.m
#implementation DistrictViewController
#synthesize districtDictionary;
And there we have it. This class is now set up to keep track of 1 NSDictionary object. Now you just have to configure your table delegate methods to show you the data you want.
The first example, what would be in the top Row (index:0) of the NSArray, you have a dictionary that has 2 keys: District 1 and District 2. But this is a problem. NSDictionary doesn't map to TableViews quite as easily, because NSDictionary objects don't use indexes to work. Don't fret. NSDictionary has a method called allKeys, which will give you an array of each key in the dictionary. This is useful for when you will be receiving an NSDictionary from somewhere but not know what keys it contains beforehand.
So, the questions your tableView asks, let's answer them:
//How many sections will be in me: Let's just say 1 for now.
//How many rows will be in this section:
//Ask the NSDictionary how many keys it has:
NSArray *keyArray = [self.districtDictionary allKeys];
return [keyArray count];
//Give me a tableCell for index path X,Y
//First, get your array of keys back:
NSArray *keyArray = [self.districtDictionary allKeys];
//Next, find the key for the given table index:
NSString *myKey = [keyArray objectAtIndex:indexPath.row];
//Finally, display this string in your cell:
cell.textLabel.text = myKey;
After this, you'd do the same thing for the final view. Set up a viewController for schools and call it SchoolViewController and make set it up to be in charge of an NSArray. Just like before:
#interface SchoolViewController : UITableViewController
#property (nonatomic, strong) NSArray *schoolArray;
#end
#implementation SchoolViewController
#synthesize schoolArray;
In this view, it will be a lot like the first. You just have this viewController answer the table's questions like before:
How many sections? We need 1
How many rows? We need as many as in the array return [schoolArray count];
Give me a cell: cell.textLabel.text = [schoolArray objectAtIndex:indexPath.row];
The final piece that puts this all together is in the final question the table asks.
What do I do when a user touches a row?
In each view, look at this method signature:
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
This is where you add your logic to hook things up. In the first view plistViewController, do this:
NSDictionary *topLevelDictionary = [self.content objectAtIndex:indexPath.row];
NSDictionary *allDistricts = [topLevelDictionary objectForKey:#"districts"];
DistrictViewController *dView = [[DistrictViewController alloc] initWithStyle:UITableViewStylePlain];
dView.districtDictionary = allDistricts;
[self.navigationController pushViewController:dView animated:YES];
In the second view, DistrictViewController do this:
NSArray *keyArray = [self.districtDictionary allKeys];
NSString *myKey = [keyArray objectAtIndex:indexPath.row];
NSArray *schoolArray = [self.districtDictionary objectForKey:myKey];
SchoolViewController *sView = [[SchoolViewController alloc]initWithStyle:UITableViewStylePlain];
sView.schoolArray = schoolArray;
[self.navigationController pushViewController:sView animated:YES];
I hope this helps you. I typed this all in a plain text editor. Hopefully there's no misspellings. You'll need to #import the associated viewControllers in each one! Good luck.

Answer 2

To create drill down tables:
you can do:
- (void)viewDidLoad
{
[super viewDidLoad];
NSArray *districts = [NSArray arrayWithObjects:#"district1", #"district2", #"district3", nil];
NSArray *states = [NSArray arrayWithObjects:#"NY", #"NJ", #"NO", #"StateOther1", #"StateOther2", nil];
NSArray *schools = [NSArray arrayWithObjects:#"", #"school1", #"school2", #"school3", #"school4", nil];
NSMutableDictionary *schoolSection = [NSMutableDictionary dictionary];
[schoolSection schools forKey:#"items"];
[schoolSection setObject:#"Shools" forKey:#"title"];
NSMutableDictionary *districtSection = [NSMutableDictionary dictionary];
[districtSection setObject:districts forKey:#"items"];
[districtSection setObject:#"Section" forKey:#"title"];
NSMutableDictionary *stateSection = [NSMutableDictionary dictionary];
[districtSection setObject:states forKey:#"items"];
[districtSection setObject:#"State" forKey:#"title"];
self.adresses = #[schoolSection, districtSection,stateSection];
}
Next:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return self.adresses.count;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSDictionary *currentSection = [self.adresses objectAtIndex:section];
if ([[currentSection objectForKey:#"isOpen"] boolValue]) {
NSArray *items = [currentSection objectForKey:#"items"];
return items.count;
}
return 0;
}
- (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];
}
NSDictionary *currentSection = [self.adresses objectAtIndex:indexPath.section];
NSArray *items = [currentSection objectForKey:#"items"];
NSString *currentItem = [items objectAtIndex:indexPath.row];
cell.textLabel.text = currentItem;
return cell;
}
Next:
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
NSDictionary *currentSection = [self.adresses objectAtIndex:section];
NSString *sectionTitle = [currentSection objectForKey:#"title"];
BOOL isOpen = [[currentSection objectForKey:#"isOpen"] boolValue];
NSString *arrowNmae = isOpen? #"arrowUp":#"arrowDown";
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(0.0f, 0.0f, 320.0f, 50.0f);
button.tag = section;
button.backgroundColor = [UIColor brownColor];
[button setTitle:sectionTitle forState:UIControlStateNormal];
[button addTarget:self action:#selector(didSelectSection:)
forControlEvents:UIControlEventTouchUpInside];
[button setImage:[UIImage imageNamed:arrowNmae] forState:UIControlStateNormal];
return button;
}
Next:
- (void)didSelectSection:(UIButton*)sender {
//get current section
NSMutableDictionary *currentSection = [self.adresses objectAtIndex:sender.tag];
//get elements of section
NSArray *items = [currentSection objectForKey:#"items"];
//create array of indexes
NSMutableArray *indexPaths = [NSMutableArray array];
for (int i=0; i<items.count; i++) {
[indexPaths addObject:[NSIndexPath indexPathForRow:i inSection:sender.tag]];
}
//get current state of section is opened
BOOL isOpen = [[currentSection objectForKey:#"isOpen"] boolValue];
//set new state
[currentSection setObject:[NSNumber numberWithBool:!isOpen] forKey:#"isOpen"];
//animate of adding and deleting of cells
if (isOpen) {
[self.tableView deleteRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationTop];
} else {
[self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationTop];
}
//reload button image
NSString *arrowNmae = isOpen? #"arrowDown.png":#"arrowUp.png";
[sender setImage:[UIImage imageNamed:arrowNmae] forState:UIControlStateNormal];
}
And you can customize this table, like you need.
Example of drill down tables you can download here (click "Скачать" button)

Answer 3

You should pass the array of districts to a new view controller that can display them. The new view controller should have a property called districts, I would also recommend creating an initializer that accepts an array of districts which sets this property.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSArray *districts = [[self.content objectAtIndex:indexPath.row] valueForKey:#"districts"];
DistrictsViewController *districtsvc =
[[DistrictsViewController alloc] initWithNibName:nil
bundle:nil
districts:districts];
[self.navigationController pushViewController:districtsvc];
}
From your example I'm not sure where the school info would come from so if it is difficult to say if you would be able to easily create a single generic view controller to drill down from state to school.