How to get the file size given a path?

This one liner can help people:

unsigned long long fileSize = [[[NSFileManager defaultManager] attributesOfItemAtPath:someFilePath error:nil] fileSize];

This returns the file size in Bytes.

Bear in mind that fileAttributesAtPath:traverseLink: is deprecated as of Mac OS X v10.5. Use attributesOfItemAtPath:error: instead, described at the same URL thesamet mentions.

With the caveat that I'm an Objective-C newbie, and I'm ignoring errors that might occur in calling attributesOfItemAtPath:error:, you can do the following:

NSString *yourPath = @"Whatever.txt";
NSFileManager *man = [NSFileManager defaultManager];
NSDictionary *attrs = [man attributesOfItemAtPath: yourPath error: NULL];
UInt32 result = [attrs fileSize];

In case some one needs a Swift version:

let attr: NSDictionary = try! NSFileManager.defaultManager().attributesOfItemAtPath(path)
print(attr.fileSize())