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I know various incarnations of this question have been asked and answered on stack overflow many times, but the closest matches that I could find focus only on unicode combinations (e.g.: character + diacritic), which end up side-stepping the real issue for me at least regarding how unicode string length is computed.

My example strings do not contain any combinatory characters:

http://static.inky.ws/image/5413/Screen%20Shot%202015-11-07%20at%2012.05.05%20AM.png

Why does -[NSString length] tell me that each of these strings (each of which, again, is just a single printable character with no extra combinatory characters) has a length of 2?

Apple's documentation for -[NSString length] says:

The number of Unicode characters in the receiver. This number includes the individual characters of composed character sequences, so you cannot use this property to determine if a string will be visible when printed or how long it will appear.

By that definition, it seems reasonable to conclude that each of these test strings has a length of 1.

Obviously I'm wrong. I just need someone to explain why.

(This question is not a duplicate of "Number of characters in a string (not number of bytes)", because the OP in that thread was not asking why.)

x154132584
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    Please post actual code instead of screenshots. [See here](http://meta.stackoverflow.com/a/285557/1402846) for details. Thank you. – Pang Nov 07 '15 at 05:38
  • @Pang, typing the football unicode character in the browser was a problem, hence the screenshot. – x154132584 Nov 07 '15 at 05:59
  • @rmaddy, thanks for pointing out the algorithm that gives me a more intuitive number for length, but I was hoping someone could provide the rationale for string API's which return a length of 2 for a string that has 1 base character and nothing else (no combinatory characters). – x154132584 Nov 07 '15 at 06:01
  • I'm writing a string class for a cross-platform project and I need to understand which methodology to use for the "length" method and most importantly... why. – x154132584 Nov 07 '15 at 06:04

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