【Swift】整数から2進数に変換する方法！FixedWidthInteger

extension FixedWidthInteger {
    var binaryString: String {
        var result: [String] = []
        for i in 0..<(Self.bitWidth / 8) {
            let byte = UInt8(truncatingIfNeeded: self >> (i * 8))
            let byteString = String(byte, radix: 2)
            let padding = String(repeating: "0",
                                count: 8 - byteString.count)
            result.append(padding + byteString)
        }
        return "0b" + result.reversed().joined(separator: "_")
    }
}


print(Int16.max.binaryString)
// Prints "0b01111111_11111111"
print((101 as UInt8).binaryString)
// Prints "0b01100101"

protocol FixedWidthInteger : BinaryInteger, LosslessStringConvertible where Self.Magnitude : FixedWidthInteger, Self.Magnitude : UnsignedInteger, Self.Stride : FixedWidthInteger, Self.Stride : SignedInteger

print(String(Int16.max,radix: 2))
// 111111111111111
print(String(101,radix: 2))
// 1100101