Capitalize strings at given indexes with Swift - swift

Question

I want to be able to capitalizes characters from a string from an array of indexes.
let string = "format"
let indexes = [0, 5]
Expected: "FormaT"
Can this be accomplished in Swift?

Answer 1

You can try and get an array of the characters, and uppercase the ones in your indexes array like this:
let string = "format"
let indexes = [0, 5]
var array = string.map{ String($0) }
indexes.forEach{ array[$0] = array[$0].uppercased() }
let fixedString = array.joined()
print(fixedString)

Answer 2

The following String extension should work for you.
extension String {
func capitalized(at characters: [Int]) -> String {
var formattedString = self
for character in characters {
formattedString = formattedString.prefix(character) + String(self[index(startIndex, offsetBy: character)]).capitalized + formattedString.dropFirst(character + 1)
}
return formattedString
}
}
And then using it:
print("format".capitalized(at: [0,2,5]))
Result: FoRmaT

Answer 3

You just need to map through the String and at each character, either return the character itself or its uppercased version in case the index of the character is contained in the indices you want to modify.
extension String {
func uppercased(at indices: [Int]) -> String {
return enumerated().map { indices.contains($0.offset) ? $0.element.uppercased() : String($0.element) }.joined()
}
}
let string = "format"
let indices = [0, 5]
print(string.uppercased(at: indices)) // "FormaT"

Answer 4

You can iterate your indices, get the index at the desired offset and replace the subrange by its uppercase:
extension StringProtocol where Self: RangeReplaceableCollection {
mutating func uppercase(at indices: [Int]) {
for offset in indices {
let index = self.index(startIndex, offsetBy: offset)
replaceSubrange(index...index, with: self[index...index].uppercased())
}
}
func uppercased(at indices: [Int]) -> Self {
var string = self
string.uppercase(at: indices)
return string
}
}
var string = "format"
let indices = [0, 5]
string.uppercase(at: indices) // "FormaT"
string
print(string.uppercased(at: [1,2])) // "FORmaT\n"