无法将类型“(_) -> ()”的值转换为预期的参数类型“(() -> Void)？”

Posted 2023-02-24

【中文标题】无法将类型“(_) -> ()”的值转换为预期的参数类型“(() -> Void)？”

【英文标题】：Cannot convert value of type '(_) -> ()' to expected argument type '(() -> Void)?'

【发布时间】：2018-05-07 20:38:50

【问题描述】：

我正在将我的代码从 Swift 2 迁移到 Swift 4，但是我不确定为什么会出现此错误：

这是我的功能：

fileprivate func navigateToTagFriends(completion: @escaping (_ taggedUsers : [Athlete]?) -> Void) 
    // Tag Users when item is original content
    if self.parentContent == nil 
        self.state = .finished // Mark as finished so friends operation will execute
        if let tagController = UIStoryboard(type: .Capture).instantiateInitialViewController() as? TagViewController 
            tagController.tagCompletionBlock =  taggedUsers in
                self.presentingViewController?.dismiss(animated: true, completion: _ in
                    if let processingView = Bundle.main.loadNibNamed("ProcessingView", owner: self, options: nil)?[0] as? UIView 
                        let size = self.presentingViewController?.view.frame.size
                        processingView.frame = CGRect(x: 0, y: 0, width: size?.width ?? 0, height: size?.height ?? 0)
                        self.processingView = processingView
                        self.presentingViewController?.view.addSubview(processingView)
                    
                    completion(taggedUsers)

                )
            
            tagController.cancelBlock = 
                self.presentingViewController?.dismiss(animated: true, completion: nil)
            
            tagController.transitioningDelegate = self
            self.presentingViewController?.present(tagController, animated: true, completion: nil)
        
     else 
        completion(nil)
    

有人知道我为什么会收到此错误以及如何解决该错误吗？

【参考方案1】：

从行中删除_ in：

self.presentingViewController?.dismiss(animated: true, completion: _ in

基于dismiss 的docs，completion 回调不接受任何参数。