NSError *error = nil;

//Change YOUR_USERNAME with your username
NSString *path = @"/Users/YOUR_USERNAME/Library/Safari/History.plist";

uint64_t fileSize = [[[NSFileManager defaultManager] attributesOfItemAtPath:path error:&error] fileSize];

if (error != nil) {
	NSLog(@"Error: %@", [error localizedDescription]);
} else {
	NSLog(@"File Size: %.0llu", fileSize);
}