Objective-C: writing values to a specific index of an Array inside a .plist

Question

I understand I can for instance write a value to a .plist file as such

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"stored" ofType:@"plist"];
NSString *comment = @"this is a comment"; 
[comment writeToFile:filePath atomically:YES];

But If i had for say an Array inside my .plist (gameArray) and I'd like to white comment into a particular index of my array i.e. gameArray[4] ; how would I do this ?

allow me to clarify

• I have a plist: stored.plist
• inside my plist there is an array gameArray
• i would like to update specific indexes of gameArray inside the plist is this possible ?

Answer 1

Assuming the contents of 'stored.plist' is an array, you need to instantiate a mutable array from the path:

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"stored" ofType:@"plist"];
NSMutableArray *array = [NSMutableArray arrayWithContentsOfFile:filePath];
NSString *comment = @"this is a comment"; 

// inserting a new object:
[array insertObject:comment atIndex:4];

// replacing an existing object:
// classic obj-c syntax
[array replaceObjectAtIndex:4 withObject:4];        
// obj-c literal syntax:
array[4] = comment;

// Cannot save to plist inside your document bundle.
// Save a copy inside ~/Library/Application Support

NSURL *documentsURL = [[[NSFileManager defaultManager] URLsForDirectory:NSApplicationSupportDirectory inDomains:NSUserDomainMask] objectAtIndex:0];
NSURL *arrayURL = [documentsURL URLByAppendingPathComponent:[filePath lastPathComponent]];
[array writeToURL:arrayURL atomically:NO];

Answer 2

You cannot update and save data in application's main bundle instead you have to do in document directory or other directory like this:

 NSArray *paths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *plistFilePath = [documentsDirectory stringByAppendingPathComponent:@"stored.plist"];

if([[NSFileManager defaultManager] fileExistsAtPAth:plistFilePath]) 
{//already exits

   NSMutableArray *data = [NSMutableArray arrayWithContentsOfFile:plistFilePath];
   //update your array here
   NSString *comment = @"this is a comment";
   [data replaceObjectAtIndex:4 withObject:comment];

   //write file here
   [data writeToFile:plistFilePath atomically:YES];
}
else{ //firstly take content from plist and then write file document directory 

 NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"stored" ofType:@"plist"];
 NSMutableArray *data = [NSMutableArray arrayWithContentsOfFile:plistPath];
 //update your array here
   NSString *comment = @"this is a comment";
   [data replaceObjectAtIndex:4 withObject:comment];

   //write file here
   [data writeToFile:plistFilePath atomically:YES];
}