Check if an NSString is just made out of spaces

Question

I want to check if a particular string is just made up of spaces. It could be any number of spaces, including zero. What is the best way to determine that?

Answer 1

I'm really surprised that I am the first who suggests Regular Expression

NSString *string = @"         ";
NSString *pattern = @"^\\s*$";
NSRegularExpression *expression = [[NSRegularExpression alloc] initWithPattern:pattern options:0 error:nil];
NSArray *matches = [expression matchesInString:string options:0 range:NSMakeRange(0, string.length)];
BOOL isOnlyWhitespace = matches.count;

Or in Swift:

let string = "         "
let pattern = "^\\s*$"
let expression = try! NSRegularExpression(pattern:pattern)
let matches = expression.matches(in: string, range: NSRange(string.startIndex..., in: string))
let isOnlyWhitespace = !matches.isEmpty

Alternatively

let string = "         "
let isOnlyWhitespace = string.range(of: "^\\s*$", options: .regularExpression) != nil