ios - 在 Swift 中制作旋转图像的动画

Question

我有一个图像，如果按下按钮，我希望它继续旋转，直到我调用一个操作来停止旋转。我尝试了这些网站:https://www.andrewcbancroft.com/2014/10/15/rotate-animation-in-swift/我必须给代表团创造机会，当我尝试改变它时它崩溃了和 https://bencoding.com/2015/07/27/spinning-uiimageview-using-swift/当我调用该操作时，只是不旋转。谢谢。代码如下:

Andrewcbancroft.com:

    extension UIView {
    func rotate360Degrees(duration: CFTimeInterval = 1.0, completionDelegate: AnyObject? = nil) {
        let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
        rotateAnimation.fromValue = 0.0
        rotateAnimation.toValue = CGFloat(M_PI * 2.0)
        rotateAnimation.duration = duration

        if let delegate: AnyObject = completionDelegate {
            rotateAnimation.delegate = delegate //<- error "Cannot assign value of type 'AnyObject' to type 'CAAnimationDelegate?'"
        }
        self.layer.add(rotateAnimation, forKey: nil)
    }
}

尝试将 delegate 转换为!尝试旋转图像时，CAAnimationDelegate 将使应用程序崩溃，并显示错误代码无法将类型“test.ViewController”(0x1074a0a60) 的值转换为“CAAnimationDelegate”(0x10cede480)。

Bending.com:

extension UIView {
    func startRotating(duration: Double = 1) {
        let kAnimationKey = "rotation"

        if self.layer.animation(forKey: kAnimationKey) == nil {
            let animate = CABasicAnimation(keyPath: "transform.rotation")
            animate.duration = duration
            animate.repeatCount = Float.infinity
            animate.fromValue = 0.0
            animate.toValue = Float(M_PI * 2.0)
            self.layer.add(animate, forKey: kAnimationKey)
        }
    }
    func stopRotating() {
        let kAnimationKey = "rotation"

        if self.layer.animation(forKey: kAnimationKey) != nil {
            self.layer.removeAnimation(forKey: kAnimationKey)
        }
    }
}

当尝试调用我的 ImageView 以在 viewDidLoad 方法中开始旋转时，没有任何反应。

Answer 1

错误解释:

您将委托(delegate)作为 AnyObject 传递

func rotate360Degrees(duration: CFTimeInterval = 1.0, completionDelegate: AnyObject? = nil)

AnyObject 不符合 CAAnimationDelegate，因此您不能将其用作委托(delegate)。

如果您确定传入的 Controller 可以是适当的委托(delegate)，则将其转换为正确类型的委托(delegate):

if let delegate = completionDelegate as? CAAnimationDelegate {
    rotateAnimation.delegate = delegate
}

如果你这样做并且它崩溃了:

rotateAnimation.delegate = completionDelegate as! CAAnimationDelegate

那么您没有传入符合CAAnimationDelegate的 Controller

根本不传递委托(delegate)并将其分配到扩展程序之外可能会更简单。