homogeneous.swift

import Foundation

extension String {
	var isHomogeneous: Bool {
		if lengthOfBytesUsingEncoding(NSUTF8StringEncoding) == 0 {
			return true
		}

		var homogeneous = true
		var character: NSString?
		let range = Range(start: startIndex, end: endIndex)
		enumerateSubstringsInRange(range, options: [.ByComposedCharacterSequences]) { substring, _, _, stop in
			if let character = character {
				if character != substring {
					homogeneous = false
					stop = true
				}
			} else {
				character = substring
			}
		}

		return homogeneous
	}
}


import XCTest

class StringExtensionTests: XCTestCase {
	func testHomogeneous() {
		XCTAssertTrue("~~~".isHomogeneous)
		XCTAssertTrue("aaa".isHomogeneous)
		XCTAssertTrue("😎😎".isHomogeneous)
		XCTAssertTrue("😎".isHomogeneous)
		XCTAssertTrue("".isHomogeneous)

		XCTAssertFalse("as".isHomogeneous)
		XCTAssertFalse(" ~~~".isHomogeneous)
	}
}

@marklarr Yes, it works!