我正在 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,而且不太整洁,所以我决定使用 for 循环和包含以下内容的字典:UISwipeRecognizer
s 作为键,并且()
函数作为值。问题是,在尝试使用添加目标时,它给了我标题中的错误recognizer.addTarget(self, action: #selector(functionForRecognizer[recognizer]!))
这是代码:
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,我尝试把@objc
虽然声明了函数,但它不起作用。另外,我尝试通过删除 SKScene 的继承并遵循 NSObject 来将类公开给 NSObject,但仍然不起作用。此外,我无法将该类符合 UIKit 类,因为我需要它作为 SKScene,甚至,我尝试将其符合 UIViewController (当然没有 SKScene),但仍然不起作用,
你想要做的事用 Swift 是不可能的#selector
。相反,插入的实例Selector
类直接存入字典。
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]))
详细解释#selector
see 这个答案 https://stackoverflow.com/a/24007718/5099014。概括,#selector
是 Swift 的编译器构造,可确保准确的选择器/方法存在,包括它应该存在的类。它查看括号内的实际内容以查看它是否是已知方法,并且functionForRecognizer[recognizer]
不是方法名,是变量+下标的方法调用。
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