动画 CALayer 锚点

Question

我已成功为图层的位置和变换（旋转）设置动画。

现在，我需要为锚点设置动画，但所有尝试都失败了！即使我这样做：

2012... App[6437:403] layer: 1, KeyPath: anchorPoint, fromValue: NSPoint: {1.05, 0.5}, toValue: NSPoint: {1.05, 0.5}, Duration: 2.5

这是在为图层设置动画之前卡住的 NSLog。我得到的结果是图层在 X 轴上向左移动太远，然后又回来……并重复（因为自动反转已打开）。

关于图层层次结构的注意事项： SuperLayer 有三个子层，我将在其上应用动画。

为什么？锚点应该如何动画化？

我的代码：

    NSArray* subKeyPath     = [keyPaths objectAtIndex:tag];
    NSArray* subToValue     = [toValues objectAtIndex:tag];
    NSArray* subDuration    = [durations objectAtIndex:tag];

    NSEnumerator* keyPathsEnum  = [subKeyPath objectEnumerator];
    NSEnumerator* toValuesEnum  = [subToValue objectEnumerator];
    NSEnumerator* durationsEnum = [subDuration objectEnumerator];

    NSString* keyPath;
    NSNumber* toValue;
    NSNumber* duration;

    while ((keyPath = [keyPathsEnum nextObject]) && (toValue = [toValuesEnum nextObject]) && (duration = [durationsEnum nextObject])) {
        CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:keyPath];

        id offsetToValue;
        if ([keyPath hasPrefix:@"position"]) {
        //I removed the position animation, since animating the anchorPoint should suffice
        } else if ([keyPath hasPrefix:@"anchorPoint"]) {
            //This was when I used anchorPoint.x float value         = [[subLayer valueForKeyPath:keyPath] floatValue] - ([toValue floatValue]/[[subLayer contents] size].width);
            offsetToValue       = [NSNumber valueWithPoint:CGPointMake(1.05, 0.5)];
            keyPath             = [keyPath substringToIndex:[keyPath length]-2];
        } else {
            offsetToValue       = toValue;
        }

...

        animation.toValue       = offsetToValue;
        animation.duration      = [duration floatValue];
        animation.fillMode      = kCAFillModeForwards;
        animation.repeatCount   = INFINITY;
        animation.autoreverses  = YES;
        animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

        [subLayer addAnimation:animation forKey:keyPath];

        //update the model

    }

我尝试为“anchorPoint.x”keyPath 设置动画，结果相同:(

最后一点，我正在编写一个 cocoa 应用程序，但是在 cocoa 和 cocoa touch 上设置 X 值的动画应该完全相同。

Answer 1

你不会相信的（好像我从一开始就和你坐在一起）..

在不设置fromValue 的情况下，动画位置和旋转工作正常。但是，为锚点设置动画需要我将锚点fromValue 设置为初始值！

animation.fromValue = [subLayer valueForKeyPath:keyPath];