Bit shift OptionSet 是 7 的倍数？ Swift 3

Question

位移选项集...

struct VerifiedOptions : OptionSet {

    let rawValue: Int

    static let facebook = VerifiedOptions(rawValue: 1 << 0)
    static let email = VerifiedOptions(rawValue: 1 << 1)
    static let phoneNumber = VerifiedOptions(rawValue: 1 << 2)

    static let count:Int = 3
}

像这样使用...

    let options:VerifiedOptions = [.facebook,.email,.phoneNumber]

    for i in 0..<VerifiedOptions.count {

        let option = VerifiedOptions(rawValue: options.rawValue << i)

        print("O:",option.rawValue,"T:",options.rawValue)

        if options.contains(option) { print("match") }
    }

打印解析为

O:7 T:7 match O:14 T:7 O:28 T:7

两个问题....

为什么位移是 7 的倍数而不是 1 的倍数？
为什么 options 中没有显示所有 3 个选项？

感谢您的宝贵时间。

Answer 1

不好意思，马上抓住了

let option = VerifiedOptions(rawValue: options.rawValue << i)

应该是

let option = VerifiedOptions(rawValue: 1 << i)

打印出来的是

O:1 T:7 match O:2 T:7 match O:4 T:7 match

1 + 2 + 4 = 7 = 二进制 111

Bit shift OptionSet 是 7 的倍数？ Swift 3

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