轉(zhuǎn)戰(zhàn)swift有幾天了,接觸到了swift中的單例，下面介紹一下swift中的單例:

仿照OC中的單例的寫(xiě)法，寫(xiě)一個(gè)常用的網(wǎng)絡(luò)處理單例

class NetworkTools: NSObject {

    static var onceToken: dispatch_once_t = 0
    
    static var tools: NetworkTools?
 //單例訪問(wèn)的函數(shù)
    class func sharedTools() -> NetworkTools {
  dispatch_once(&onceToken) { () -> Void in
            tools = NetworkTools()
        }
        return tools!   
    }
}

上面的寫(xiě)法也是單例，但是沒(méi)有swift范，下面的才是swift中的真正的單例

class NetworkTools: NSObject {
    
    var post: String?
    //  swift單例的寫(xiě)法
    static let networkTools: NetworkTools = {
        let network = NetworkTools()
        network.post = "Post"
        return network
    }()

如果在創(chuàng)建單例時(shí)不需要做任何操作的話(huà)，你完全可以這樣寫(xiě)

class NetworkTools: NSObject {

var post: String?

static let networkTools: NetworkTools = NetworkTools()
}

調(diào)用時(shí)直接點(diǎn)出來(lái)方法并使用即可

 let tools = NetworkTools.networkTools