swift - 可选的关闭并检查是否为零

所以我想要的是一个可以在函数中传递闭包的类，也可能在某个时候忽略该闭包。完成设置后，如何检查是否设置了关闭变量？如何删除它？

class someClass{
    //typealias completionHandlerClosureType = (sucsess:Bool!, items:[AnyObject]!)->()
    var completionHandler:(sucsess:Bool!, items:[AnyObject]!)->()?
    var hitpoints = 100
    var someset = ["oh no!","avenge me!"]
    init(){}

    func getHitFunc(impact:Int, passedCompletionsHandler:(sucsess:Bool!, items:[AnyObject]!)->()){
        completionHandler = passedCompletionsHandler
        hitpoints = hitpoints - impact
    }

    func checkIfDead{
        if hitpoints<=0 {               // The error received
            if completionHandler != nil{// Cannot invoke '!=' with an argument list of type
                                        //'(@lvalue (sucsess: Bool!, products: [AnyObject]!) -> ()?, NilLiteralConvertible)'
                //run the handler if dead
                completionHandler(sucsess: true, items: someset)
                //do not run it again
                completionHandler = nil     //Type '(sucsess: Bool!, products: [AnyObject]!) -> ()?' does not conform to protocol 'NilLiteralConvertible'
            }
        }
        else{
            completionHandler = nil      //Type '(sucsess: Bool!, products: [AnyObject]!) -> ()?' does not conform to protocol 'NilLiteralConvertible'
        }
    }
}

最佳答案

您需要将闭包签名包装在括号中，以使闭包本身成为可选的。按照现在的编写方式，闭包返回一个可选的Void(这实际上没有意义)。

var completionHandler: ((sucsess:Bool!, items:[AnyObject]!)->())?

对示例代码的一些样式点和修订:

 // Capitalize class names so it's clear what's a class
class SomeClass {
    // "success" has two "c"s
    var completionHandler: ((success:Bool!, items:[AnyObject]!)->())?
    var hitpoints = 100
    var someset = ["oh no!","avenge me!"]

    init() { }

    func getHitFunc(impact:Int, passedCompletionsHandler:(success:Bool!, items:[AnyObject]!)->()){
        completionHandler = passedCompletionsHandler
        hitpoints = hitpoints - impact
    }

    // You were missing the argument list here:
    func checkIfDead() {
        if hitpoints <= 0 {

            // Rather than checking to see if the completion handler exists, you can
            // just call it using optional syntax like this:
            completionHandler?(success: true, items: someset)
        }
        completionHandler = nil
    }
}