Apple WebObjects 3.5 - Manual (Page 200)

Chapter 11 WebScript Programmer’s Quick Reference to Foundation Classes
200
Storing Arrays
– writeToFile:atomically:
Writes the array’s string representation to a specified file using the
description method. Returns YES on success and NO on failure. If YES
is specified for atomically: , this method attempts to write the file safely
so that an existing file with the specified path is not overwritten, and
it does not create a new file at the specified path unless the write is
successful. The resulting file is suitable for use with
arrayWithContentsOfFile: . For example, the following code excerpt creates
guestArray with the contents of the specified file, adds a new guest, and
saves the changes to the same file:
id guestArray = [NSMutableArray arrayWithContentsOfFile:path];
[guestArray addObject:newGuest];
[guestArray writeToFile:path atomically:YES];
Representing Arrays as Strings
– description
Returns a string that represents the contents of the receiver. For
example, the following code excerpt produces the string “(Plates,
Plasticware, Napkins)”:
id array = [NSMutableArray arrayWithObjects:
@"Plates", @"Plasticware", @"Napkins", nil];
id description = [array description];
– componentsJoinedByString:
Returns an NSString created by interposing a specified string between
the elements of the receiver’s objects. Each element of the array must
be a string. If the receiver has no elements, an empty string is returned.
See also
componentsSeparatedByString: (page 193). For example, the
following code excerpt creates the NSString dashString with the contents
“A-B-C”:
id commaString = @"A, B, C";
id array = [string componentsSeparatedByString:@","];
id dashString = [array componentsJoinedByString:@"-"];
Working With Dictionaries
NSDictionary and NSMutableDictionary objects store collections of key-value
pairs. The key-value pairs within a dictionary are called entries. Each entry
consists of an object that represents the key, and a second object that represents