StringProtocol+Subscript.swift

extension StringProtocol {
    
    subscript(_ offset: Int) -> String.Element {
        if offset >= 0 {
            self[index(startIndex, offsetBy: offset)]
        } else {
            self[index(endIndex, offsetBy: offset)]
        }
    }
    
    subscript(_ offsetRange: Range<Int>) -> SubSequence {
        self[Range<String.Index>(
            uncheckedBounds: (
                lower: index(startIndex, offsetBy: offsetRange.lowerBound),
                upper: index(startIndex, offsetBy: offsetRange.upperBound)
            )
        )]
    }
    
    subscript(_ offsetRange: ClosedRange<Int>) -> SubSequence {
        self[ClosedRange<String.Index>(
            uncheckedBounds: (
                lower: index(startIndex, offsetBy: offsetRange.lowerBound),
                upper: index(startIndex, offsetBy: offsetRange.upperBound)
            )
        )]
    }
}

let text = "🧗🏾‍♂️iOS Broadcast 🚀🗿"
print(text[0]) // 🧗🏾‍♂️
print(text[-1]) // 🗿
print(text[1]) // i
print(text[5...13]) // Broadcast
print(text[5...40]) // ❌ EXC_BREAKPOINT