所以我想要的是一个类，可能会得到一个闭包传递给它在一个函数，它也可能在某些时候想忽略一个闭包。如何检查闭包变量是否设置和hwo可以删除它，当我完成它？
Cannot invoke ‘!=’ with an argument list of type ‘(@lvalue (sucsess:
Bool!,products: [AnyObject]!) -> ()?,NilLiteralConvertible)’ Type
‘(sucsess: Bool!,products: [AnyObject]!) -> ()?’ does not conform to
protocol ‘NilLiteralConvertible’
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!,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'
}
}
}
你需要在括号中包装你的闭包签名，使闭包本身是可选的。现在写的方式，闭包返回一个可选的Void(这不是真的有意义)。
原文链接：https://www.f2er.com/swift/321036.htmlvar completionHandler: ((sucsess:Bool!,items:[AnyObject]!)->())?
您的示例代码的一些样式点和修订版本：
// 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
}
}
