如何在OptionSetType上执行"〜"(按位NOT)

Question

直到Swift 1.2你可以~在位掩码上执行(NOT):

bitmask = ~otherBitmask

但是在Swift 2.0中,bitmasks现在已经OptionSetType无法使用a ~了OptionSetType,你现在如何对a进行~操作OptionSetType？

Answer 1

您可以对原始值执行"按位NOT".例:

let otherBitmask : NSCalendarOptions = [.MatchLast, .MatchNextTime]
let bitmask = NSCalendarOptions(rawValue: ~otherBitmask.rawValue)

如果您经常需要,可以为以下内容定义通用 ~运算符OptionSetType:

prefix func ~<T : OptionSetType where T.RawValue : BitwiseOperationsType>(rhs: T) -> T {
    return T(rawValue: ~rhs.rawValue)
}

let otherBitmask : NSCalendarOptions = [.MatchLast, .MatchNextTime]
let bitmask = ~otherBitmask