How to display OptionSet values in human-readable form?

Question

Swift has the OptionSet type, which basically adds set operations to C-Style bit flags. Apple is using them pretty extensively in their frameworks. Examples include the options

Answer 1

StrOptionSet Protocol:

• Add a labels set property to test each label value on Self.

StrOptionSet Extension:

• Filter out which is not intersected.
• Return the label text as array.
• Joined with "," as CustomStringConvertible::description

Here is the snippet:

protocol StrOptionSet : OptionSet, CustomStringConvertible {
    typealias Label = (Self, String)
    static var labels: [Label] { get }
}
extension StrOptionSet {
    var strs: [String] { return Self.labels
                                .filter{ (label: Label) in self.intersection(label.0).isEmpty == false }
                                .map{    (label: Label) in label.1 }
    }
    public var description: String { return strs.joined(separator: ",") }
}

Add the label set for target option set VTDecodeInfoFlags.

extension VTDecodeInfoFlags : StrOptionSet {
    static var labels: [Label] { return [
        (.asynchronous, "asynchronous"),
        (.frameDropped, "frameDropped"),
        (.imageBufferModifiable, "imageBufferModifiable")
    ]}
}

Use it

let flags: VTDecodeInfoFlags = [.asynchronous, .frameDropped]
print("flags:", flags) // output: flags: .asynchronous,frameDropped