swift - How to I get the first or last few characters of a string in a method chain? -


if use functional-style method chains string manipulation, can not use usual machinery getting first or last few characters: not have access reference current string, can not compute indices.

example:

[some, nasty, objects]     .map( { $0.ashex } )     .joined()     .<first 100>     .uppercased()     + "..." 

for truncated debug output.

so how implement <first 100>, or have break chain?

i don't know of api this. fortunately, writing our own easy exercise:

extension string {     func taking(first: int) -> string {         if first <= 0 {             return ""         } else if let = self.index(self.startindex,                                        offsetby: first,                                        limitedby: self.endindex) {             return self.substring(to: to)         } else {             return self         }     } } 

taking end similar.

find full code (including variants) , tests here.


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