Global constant
let _SingletonSharedInstance = Singleton()
class Singleton {
class var sharedInstance : Singleton {
return _SingletonSharedInstance
}
}
Nested struct
class Singleton {
class var sharedInstance : Singleton {
struct Static {
static let instance : Singleton = Singleton()
}
return Static.instance
}
}
dispatch_once
class Singleton {
class var sharedInstance : Singleton {
struct Static {
static var onceToken : dispatch_once_t = 0
static var instance : Singleton? = nil
}
dispatch_once(&Static.onceToken) {
Static.instance = Singleton()
}
return Static.instance!
}
}
