ios - substring of the first 4 characters from a textField in Swift 4 -
i'm trying create substring of first 4 characters entered in textfield in swift 4 on ios app.
since change swift 4 i'm struggling basic string parsing.
so based on apple documentation i'm assuming need use substring.index function , understand second parameter (offsetby) number of characters create substring with. i'm unsure how tell swift start @ beginning of string.
this code far:
let postcode = textfieldpostcode.text let newpostcode = postcode?.index(startatthebeginingofthestring, offsetby: 4)
i hope explanation makes sense, happy answer questions on this.
thanks,
in swift 4 can use
let string = "hello world" let first4 = string.prefix(4) // hell
the type of result new type substring
behaves similar string
. if first4
supposed leave current scope – example return value of function – it's recommended create string
explicitly:
let first4 = string(string.prefix(4)) // hell
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