let predicate = NSPredicate(format: "(SELF CONTAINS[cd] '，')") let predicate2 = NSPredicate(format: "(SELF CONTAINS '，')") let a = predicate.evaluate(with: ",") let b = predicate2.evaluate(with: ",") who knows why 'a' is true and 'b' is false, please tell me. I think 'a' should be false, is that i miss something.
NSPredicate evaluates wrong
Because predicate uses the d flag, which tells it to be diacritical insensitive, which enables a whole bunch of fuzzy matching. Your test uses two different commas, U+FF0C FULLWIDTH COMMA and U+002C COMMA, and those are considered the same when this fuzzy matching is enabled.
ps It’d help if you posted code snippets in a code block, per tip 5 in Quinn’s Top Ten DevForums Tips.
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Thank you for your answer, but use only c flag will return same result, is that prove d flag is not the reason cause that? Only when no c and d flag, the result will be the expectation i want. I want to keep c flag, please explain it more detail. And if i want to keep d flag two, what should i do to make different in this two commas, is this two commas are diacritical insensitive relationship?
use only
cflag will return same result
Interesting. However, it doesn’t really change the story here. Comparing strings is fundamentally a locale-sensitive thing. Once you engage one of these flags, you opt in to a bunch of locale-sensitive behaviour. I’m kinda surprised by this specific behaviour, but it falls into the general category of “weird locale-sensitive string comparison behaviours”, which is a big category (-:
Can you explain more about the context here? Commas are obviously not case-sensitive so the simple workaround here is to drop both c and d. However, I suspect that won’t work for you because of big picture concerns. What are you using this predicate for?
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