如何禁用CALayer隐式动画？

Question

这让我疯狂!我正在制作绘图应用程序.假设我正在制作一张UIView名片.

我在这个视图([sheet.layer addSublayer:...])中添加了一些子图层然后我想要绘制它们.为此,我正在创建一个CGImageRef并将其放入图层中contents.但它是动画的,我不希望这样.

我尝试了一切:

• removeAnimationForKey:
• removeAllAnimations
• 设置动作字典
• 使用动作层 delegate
• [CATransaction setDisableAnimations:YES]

这似乎是正确的.我不明白为什么这个图层仍然是动画的; _;
难道我做错了什么？有秘密的方式吗？

Answer 1

您必须通过将代码包装在CATransaction中来显式禁用动画

[CATransaction begin];
[CATransaction setValue:(id)kCFBooleanTrue
                 forKey:kCATransactionDisableActions];
layer.content = someImageRef;
[CATransaction commit];

Answer 2

迅速

CATransaction.begin()
CATransaction.setDisableActions(true)

// change layer properties that you don't want to animate

CATransaction.commit()

Answer 3

从Mac OS X 10.6和iOS 3开始,CATransaction还有一个setDisableActions设置key值的方法kCATransactionDisableActions.

[CATransaction begin];
[CATransaction setDisableActions:YES];

layer.content = someImageRef;

[CATransaction commit];

在Swift中,我喜欢使用这种扩展方法:

extension CATransaction {
    class func withDisabledActions<T>(_ body: () throws -> T) rethrows -> T {
        CATransaction.begin()
        CATransaction.setDisableActions(true)
        defer {
            CATransaction.commit()
        }
        return try body()
    }
}

然后你可以像这样使用它:

CATransaction.withDisabledActions {
    // your stuff here
}

Answer 4

其他方式:

1. 您应该禁用sheet.layer的默认动画,在添加子图层时会隐式调用它.

2. 您还应该对每个子图层进行内容动画处理.当然,每次设置sublayer.content时都可以使用CATransaction的"kCATransactionDisableActions".但是,您可以在创建子图层时禁用此动画一次.

这是代码:

// disable animation of container
sheet.layer.actions = [NSDictionary dictionaryWithObject:[NSNull null] 
                                                  forKey:@"sublayers"];

// disable animation of each sublayer
sublayer.layer.actions = [NSDictionary dictionaryWithObject:[NSNull null] 
                                                     forKey:@"content"];

// maybe, you'll also have to disable "onOrderIn"-action of each sublayer.       

Answer 5

层扩展：

extension CALayer {    
    var areAnimationsEnabled: Bool {
        get { delegate == nil }
        set { delegate = newValue ? nil : CALayerAnimationsDisablingDelegate.shared }
    }
}

private class CALayerAnimationsDisablingDelegate: NSObject, CALayerDelegate {
    static let shared = CALayerAnimationsDisablingDelegate()
    private let null = NSNull()

    func action(for layer: CALayer, forKey event: String) -> CAAction? {
        null
    }
}

用法：

anyLayer.areAnimationsEnabled = false

Answer 6

Swift 4扩展名：

extension CATransaction {

    static func disableAnimations(_ completion: () -> Void) {
        CATransaction.begin()
        CATransaction.setDisableActions(true)
        completion()
        CATransaction.commit()
    }

}

用法：

    CATransaction.disableAnimations {
        // things you don't want to animate
    }