CODEWITHSUNDEEP
arraysswiftswift4
SirCJ
SirCJ

Reputation: 515

Checking if an array contains a string

I'm trying to evaluate if an entered string partially matches any item in an array. When I use the following method in playgrounds it seems to work properly. However, when I use the exact same method in Xcode 9.0 beta 6 (9M214v) it doesn't return the correct answer. 

func isValid(_ item: String)  -> Bool {
    let whitelist = ["https://apple.com","https://facebook.com","https://stackoverflow.com"]

    return whitelist.contains(where: {$0 <= item ? true : false  })
}

There's also anomalies like when I passed in "https://twitter.com" it'll return true. Am I nuts? And while I'm here, anyone have a different approach to solve this problem?

Upvotes: 1

Views: 7252

Answers (2)

Ahmad F
Ahmad F

Reputation: 31645

theres also anomalies like when I passed in "https://twitter.com" it'll return true.

Whether the version of Swift is 3 or 4, based on your code snippet you should get the same true result! Why?

because the logic of contains(where:) of doing the comparison is related to the logic of the equality of the given elements, i,e you cannot use contains with array of non-equatable elements. To make it more clear: 

"https://apple.com" <= "https://twitter.com"
"https://facebook.com" <= "https://twitter.com"
"https://stackoverflow.com" <= "https://twitter.com"

the result would be true for all statements ('t' character is greater than 'a', 'f' and 's').

Thus:

"https://zwebsite" <= "https://twitter.com"

would returns false ('t' is less than 'z').

However, to get the expected result, you could implement your function like this:

func isValid(_ item: String)  -> Bool {

    let whitelist = ["https://apple.com","https://facebook.com","https://stackoverflow.com"]

    return whitelist.contains { $0 == item }
}

Or for even a shorter contains:

return whitelist.contains(item)

Which leads to let 

isValid("https://twitter.com")

to returns false.

Upvotes: 3

Rashwan L
Rashwan L

Reputation: 38833

Just return the following, which will return true or false:

return whitelist.contains(item)

Upvotes: 0

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