How to remove duplicate characters from a string in Swift

string, swift

Solution

Edit/update: Swift 4.2 or later

You can use a set to filter your duplicated characters:

let str = "bookkeeper"
var set = Set<Character>()
let squeezed = str.filter{ set.insert($0).inserted } 

print(squeezed)   //  "bokepr"

Or as an extension on `RangeReplaceableCollection` which will also extend String and Substrings as well:

extension RangeReplaceableCollection where Element: Hashable {
    var squeezed: Self {
        var set = Set<Element>()
        return filter{ set.insert($0).inserted }
    }
}

let str = "bookkeeper"
print(str.squeezed)      //  "bokepr"
print(str[...].squeezed) //  "bokepr"

Problem

ruby has the function string.squeeze, but I can't seem to find a swift equivalent. For example I want to turn bookkeeper -> bokepr Is my only option to create a set of the characters and then pull the characters from the set back to a string? Is there a better way to do this?

Original source

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