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)。
- var 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
- }
- }