How can I save each time a new data to my plist file rather than replace the old one?

Question

I read from plist file and add data to tableview

My plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
    <dict>
        <key>Title</key>
        <string>Section1</string>
        <key>Rows</key>
        <array>
            <string>Section1 Item1</string>
            <string>Section1 Item2</string>
        </array>
    </dict>
    <dict>
        <key>Title</key>
        <string>Section2</string>
        <key>Rows</key>
        <array>
            <string>Section2 Item1</string>
            <string>Section2 Item2</string>
        </array>
    </dict>
</array>
</plist>

.h

#import "RootViewController.h"

@interface RootViewController ()

@property (copy, nonatomic) NSArray* tableData;

@end

.m

@implementation RootViewController

@synthesize tableData;

- (void) dealloc
{
    self.tableData = nil;
    [super dealloc];
}

- (void) viewDidLoad
{
    [super viewDidLoad];
    self.tableData = [NSArray arrayWithContentsOfFile: [[NSBundle mainBundle] pathForResource: @"Table" ofType: @"plist"]];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView;
{
    return [tableData count];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section;
{
    return [[[tableData objectAtIndex: section] objectForKey: @"Rows"] count];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section;
{
    return [[tableData objectAtIndex: section] objectForKey: @"Title"];
}

- (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];
    }

    cell.textLabel.text = [[[tableData objectAtIndex: indexPath.section] objectForKey: @"Rows"] objectAtIndex: indexPath.row];

    return cell;
}

@end

How can I write to that strings and arrays each time a new data rather than replace the old one?

Answer 1

With this code you read the plist file:

self.tableData = [NSArray arrayWithContentsOfFile: [[NSBundle mainBundle] pathForResource: @"Table" ofType: @"plist"]];

and with this you write:

[self.tableData writeToFile:path atomically:YES];

if you don't want to add more items just add to self.tableData and when you write to file it will be added to the plist.

The only problem is that you`l need to write on documents directory not on bundle. the bundle is your app folder, signed and approved by appstore. to edit a file that was on your bundle you should copy it first and then use the copy, like this:

  NSError *error;
  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString *documentsDirectory = [paths objectAtIndex:0];
  NSString *path = [documentsDirectory stringByAppendingPathComponent:[@"Table" stringByAppendingPathExtension:@"plist"]];

  NSFileManager *fileManager = [NSFileManager defaultManager];

  if (![fileManager fileExistsAtPath: path]) {
    NSString *bundle = [[NSBundle mainBundle] pathForResource:name ofType:@"plist"];

    [fileManager copyItemAtPath:bundle toPath: path error:&error];
  }

at the end of this code path is the path to a plist file on documents directory that will be exactly the same of Table.plist on your bundle.

this file at path you can write and read, the file at [[NSBundle mainBundle] pathForResource: @"Table" ofType: @"plist"] you can only read.

EDIT

Basically you`l need to do something like this: https://gist.github.com/3090009

this is a helper class to work with file paths, if you have questions just ask