How can i mask the first and last characters in Swift?-CodePudding

I have an extension to mask the first and last characters. When I try to mask last characters it works but if I try to mask the first characters it doesn't mask as I want to.

For example;

extension String {
    func maskedChar(_ charCount: Int, lastCharacters: Bool = true) -> String {
        if self.count <= charCount {
            return self
        }
        let mask = String(repeating: "*", count: charCount)
        return lastCharacters ? self.prefix(self.count - charCount)   mask : self.suffix(self.count - charCount)   mask
    }
}

let sample = "123456"
print(sample.maskedChar(3))
print(sample.maskedChar(3, lastCharacters: false))

// 123***
// 456***

What I want to see is basically ***456.

And also, is there any way to shorten the code? The return line is too long to see it.

CodePudding user response：

Pretty simple, really. You just need to reverse the order of the characters from the string and the mask in the "not lastCharacters" case:

extension String {
    func maskedChar(_ charCount: Int, lastCharacters: Bool = true) -> String {
        if self.count < charCount {
            return String(repeating: "*", count: self.count)
        }
        let mask = String(repeating: "*", count: charCount)
        if lastCharacters {
            return self.prefix(self.count - charCount)   mask
        } else {
            return mask   self.suffix(self.count - charCount)
        }
    }
}

Note that I also changed the if clause at the beginning. It seems to me you should ALWAYS mask the data, even if the source string is too short.

CodePudding user response：

I would use dropFirst/dropLast together with the mask you create

extension String {
    func maskedChar(_ charCount: Int, lastCharacters: Bool = true) -> String {
        if self.count <= charCount { return self }

        let mask = String(repeating: "*", count: charCount)
        return lastCharacters ? self.dropLast(charCount)   mask : mask   self.dropFirst(charCount)
    }
}