Swift 1.2 单例实现
第一种:类常量
class Singleton: NSObject {
// 类常量
static let sharedInstance = Singleton()
private override init() {
super.init()
}
}
第二种:嵌套结构体
class Singleton: NSObject {
// 嵌套结构体
class var sharedInstance: Singleton{
struct Static {
static let instance: Singleton = Singleton()
}
return Static.instance
}
private override init() {
super.init()
}
}
第三种:GCD:dispatch_once
class Singleton: NSObject {
// GCD:dispatch_once
class var sharedInstance:Singleton {
struct Static {
static var onceToken:dispatch_once_t = 0
static var instance:Singleton? = nil
}
dispatch_once(&Static.onceToken, { () -> Void in
Static.instance = Singleton()
})
return Static.instance!
}
private override init() {
super.init()
}
}
参考:http://stackoverflow.com/questions/24024549/dispatch-once-singleton-model-in-swift