How to save data on the next index of plist - iphone

Question

im a newbie to iOS programming and getting my hands dirty on it. I searched on the net for some plist help and got something and understood it and used it but now im stuck at a point. I have searched alot for this problem. but im just unable to find the correct answer for me.
Problem:
My UI has just 2 text Fields and 1 Save Button.
1 textfield takes string while the other takes number (int) as input.
my plist has 1 dictionary item, that has 1 string item and 1 int item. thats it.
i take input in 2 UITextViews from user and save them into this plist via a save Button.
The problem is that whenever i enter new values and press the save button, it overwrites the old plist data.
I found out that i need to read the dictionary, append new values to it and then save it back in order to get my desired output. but im not able to grab this concept and put it into code. some code with explanation would really help.
my save button works like this:
-(IBAction)saveit
{
// get paths from root direcory
NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
// get documents path
NSString *documentsPath = [paths objectAtIndex:0];
// get the path to our Data/plist file
NSString *plistPath = [documentsPath stringByAppendingPathComponent:#"data.plist"];
// set the variables to the values in the UITextField text1 n text2 respectively
self.personName = text1.text;
num = (int)text2.text;
// create dictionary with values in UITextFields
NSDictionary *plistDict = [NSDictionary dictionaryWithObjects: [NSArray arrayWithObjects: personName, num, nil] forKeys:[NSArray arrayWithObjects: #"name", #"phone", nil]];
NSString *error = nil;
// create NSData from dictionary
NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:plistDict format:NSPropertyListXMLFormat_v1_0 errorDescription:&error];
// check is plistData exists
if(plistData)
{
// write plistData to our Data.plist file
[plistData writeToFile:plistPath atomically:YES];
}
else
{
NSLog(#"Error in saveData: %#", error);
// [error release];
}
}
Tthis code is working fine just that it is over writing new values. please help.

Answer 1

Your plist will return a dictionary.Retrieve that dictionary as NSMutableDictionary and add your new key pair value to that dictionary and then save it.

Answer 2

Save the data as an array of dictionaries like this
// get paths from root direcory
NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];
NSString *plistPath = [documentsPath stringByAppendingPathComponent:#"data.plist"];
//Load the original file
NSMutableArray *arr;
if([[NSFileManager defaultManager] fileExistsAtPath:plistPath])
//File exist load
arr = [[NSMutableArray alloc] initWithContentsOfFile:plistPath];
else
//File does not exist create
arr = [[NSMutableArray alloc] init];
//Create dictionary
NSDictionary *plistDict = [NSDictionary dictionaryWithObjects: [NSArray arrayWithObjects: personName, num, nil] forKeys:[NSArray arrayWithObjects: #"name", #"phone", nil]];
//Append to arr
[arr addObject:plistDict];
//Save to file
[arr writeToFile:plistPath atomically:YES];