read and write from documents directory

read_and_write_in_objc.m

- (NSString *)documentPathForFile:(NSString *)fileName
{
	NSArray *pathArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
    NSString *documentPath = [pathArray objectAtIndex:0];	
    NSString *filePath = [documentPath stringByAppendingPathComponent:fileName];	
	return filePath;
	// return [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:fileName];
}

- (NSMutableArray *)loadLocalBooksFromDocument:(NSString *)fileName
{
	NSString *filePath = [self documentPathForFile:fileName];
	NSMutableArray *array = [[[NSMutableArray alloc] initWithContentsOfFile:filePath] autorelease];
	return array;
}

- (void)handleDocumentFile
{
	NSString *filePath = [self documentPathForFile:@"local.plist"];
	NSFileManager *fileManager = [NSFileManager defaultManager];
	if (![fileManager fileExistsAtPath:filePath]) {
		NSMutableArray *initArray = [[[NSMutableArray alloc] initWithCapacity:0] autorelease];
		[initArray writeToFile:filePath atomically:YES];
	}
	
	// create a directory
	NSString *dir = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"book"];
	if (![fileManager fileExistsAtPath:dir]) {
		[fileManager createDirectoryAtPath:dir withIntermediateDirectories:YES attributes:nil error:nil];		
	} else {
		// destroy a directory
		if ([fileManager isDeletableFileAtPath:dir]) {
			[fileManager removeItemAtPath:dir error:nil];
		}				
	}
				
	// read local books 
	self.localArray = [self loadLocalBooksFromDocument:@"local.plist"];
	
	// write to local books
	[self.localArray addObject:@"Book one"];
	[self.localArray addObject:@"Book two"];	
	[self.localArray writeToFile:filePath atomically:YES];		
}