Initializer
init(qos:flags:block:)
iOS 8.0+
iPadOS 8.0+
Mac Catalyst 8.0+
macOS 10.10+
init(qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], block: @escaping () -> ())Initializer
init(qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], block: @escaping () -> ())