#selector&#39；的参数没有引用&#39；@objc&#39；方法(快速3) [英] Argument of '#selector' does not refer to an '@objc' method (swift 3)

问题描述

我正在我的SKScene中设置滑动识别，我发现对所有识别器进行硬编码需要时间，而且不是很整洁，所以我决定使用for循环，以及一个包含UISwipeRecognizer作为键、()作为值的字典。问题是，在尝试使用recognizer.addTarget(self, action: #selector(functionForRecognizer[recognizer]!))

添加目标时，它在标题中显示错误

代码如下：

class xxxxx: SKScene {

let rightSwipeRecognizer = UISwipeGestureRecognizer()
let leftSwipeRecognizer = UISwipeGestureRecognizer()
let upSwipeRecognizer = UISwipeGestureRecognizer()
let downSwipeRecognizer = UISwipeGestureRecognizer()

var swipeRecognizers: [UISwipeGestureRecognizer] {
    return [rightSwipeRecognizer, leftSwipeRecognizer, upSwipeRecognizer, downSwipeRecognizer]
}

var directionForRecognizer: [UISwipeGestureRecognizer : UISwipeGestureRecognizerDirection] {
    return [
        rightSwipeRecognizer : .right,
        leftSwipeRecognizer : .left,
        upSwipeRecognizer : .up,
        downSwipeRecognizer : .down
    ]
}

func didSwipeRight() {}
func didSwipeLeft() {}
func didSwipeUp() {}
func didSwipeDown() {}

var functionForRecognizer: [UISwipeGestureRecognizer : ()] {
    return [
        rightSwipeRecognizer : didSwipeRight(),
        leftSwipeRecognizer : didSwipeLeft(),
        upSwipeRecognizer : didSwipeUp(),
        downSwipeRecognizer : didSwipeDown()
    ]
}

func setupSwipeRecognizers() {
    for recognizer in swipeRecognizers {
        recognizer.addTarget(self, action: #selector(functionForRecognizer[recognizer]!))
        recognizer.direction = directionForRecognizer[recognizer]!
        self.view?.addGestureRecognizer(recognizer)
    }
}

override func didMove(to view: SKView) {
    super.didMove(to: view)
    setupSwipeRecognizers()
}

}

顺便说一句，我试着在声明函数时放入@objc，但不起作用。此外，我尝试通过移除SKScene的继承并遵循NSObject来将类公开给NSObject，但仍然不起作用。此外，我不能使类符合UIKit类，Cz我需要它作为SKScene，甚至，我尝试将其符合UIView控制器(当然，没有SKScene)，但仍然不起作用，

推荐答案

您尝试使用SWIFT的#selector无法完成的操作。而应将Selector类的实例直接插入词典。

您还需要使用@objc进行注释

@objc // This annotation isn't required in Swift 3, but will be in Swift 4
func didSwipeRight() {}

var functionForRecognizer: [UISwipeGestureRecognizer : Selector] {
    return [
        rightSwipeRecognizer : #selector(didSwipeRight)
    ]
}

recognizer.addTarget(self, action: functionForRecognizer[recognizer]))

#selector的详细说明请参阅this answer。总而言之，#selector是SWIFT的编译器构造，它确保存在准确的选择器/方法，包括它应该存在的类。它查看括号中的实际内容，以确定它是否是已知方法，functionForRecognizer[recognizer]不是方法名，它是变量+下标方法调用。

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