Question

晚上，我的VC中有2个show segues。但是我只想在我的pickerView有一个row.count > 0时才会触发这些segues。

这就是我所拥有的：

Override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

if segue.identifier == "searchImages" {

    if pickerView.numberOfRows(inComponent: 0) > 0  {

        let controller = (segue.destination) as! WebViewController
        //replacing " " with "+" for google search queries
        let type: WebViewController.SearchType = .image
        let queryString = String(nameLabel.text!.characters.map {
                    $0 == " " ? "+" : $0
        })
        controller.searchType = type
        controller.queryString = queryString
        print("2")
        }

        }
        if segue.identifier == "searchWiki" {

        if pickerView.numberOfRows(inComponent: 0) > 0  {
            let controller = (segue.destination) as! WebViewController
            //replacing " " with "+" for google search queries
            let type: WebViewController.SearchType = .wiki
            let queryString = String(nameLabel.text!.characters.map {
                    $0 == " " ? "+" : $0
            })
            controller.searchType = type
            controller.queryString = queryString
        }
    }
}

我知道我应该使用：ShouldperformSomething。但我不知道热用它。有什么提示吗？

Answer 1

您应该实施shouldPerformSegue，而不是在pickerView.numberOfRows(inComponent: 0) > 0方法中检查prepareForSegue。

P.S：Swift 3 Code（我认为这就是你想要的）。

override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {
        return pickerView.numberOfRows(inComponent: 0) > 0
}

现在，prepareForSegue方法应类似于：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "searchImages" {
            let controller = (segue.destination) as! WebViewController
            //replacing " " with "+" for google search queries
            let type: WebViewController.SearchType = .image
            let queryString = String(nameLabel.text!.characters.map {
                $0 == " " ? "+" : $0
            })
            controller.searchType = type
            controller.queryString = queryString
            print("2")

        }

        if segue.identifier == "searchWiki" {
            let controller = (segue.destination) as! WebViewController
            //replacing " " with "+" for google search queries
            let type: WebViewController.SearchType = .wiki
            let queryString = String(nameLabel.text!.characters.map {
                $0 == " " ? "+" : $0
            })
            controller.searchType = type
        }
    }

希望这会有所帮助。

Answer 2

你不应该对UIStoryboardSegue的prepare委托进行检查，而是在shouldPerform上进行检查：

override func shouldPerformSegueWithIdentifier(identifier: String!, sender: AnyObject!) -> Bool {
    return pickerView.numberOfRows(inComponent: 0) > 0
}

我想要时执行segues

2 个答案: