CABasicAnimation不工作

Question

我试图动画一个圆形的笔画(从另一个所以answer)。我正试图在一个基于可可的应用程序中这样做。

但是，它不起作用，animationDidStop:finished:立即被finished标记调用为NO。为什么会发生这种情况？关于如何获得finished标志为NO的一些信息的任何提示

下面是我使用的代码：

注意：quartzPath和NSColorToCGColor来自NSColor和NSBezierPath上的类别。

- (IBAction)animateCircle:(id)sender {

    int radius = 10;
    circle = [CAShapeLayer layer];
    // Make a circular shape
    circle.path =  [[NSBezierPath bezierPathWithOvalInRect:NSMakeRect(10, 10, 2.0*radius, 2.0*radius)] quartzPath] ;
    // Center the shape in self.view
    circle.position = CGPointMake(CGRectGetMidX(self.vcForCellView.view.frame)-radius, 
                                  CGRectGetMidY(self.vcForCellView.view.frame)-radius);

    // Configure the apperence of the circle
    circle.fillColor =  [NSColor NSColorToCGColor:[NSColor clearColor]];
    circle.strokeColor = [NSColor NSColorToCGColor:[NSColor blackColor]];
    circle.lineWidth = 5;

    // Add to parent layer
    [self.vcForCellView.view.layer addSublayer:circle];

    // Configure animation
    CABasicAnimation *drawAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
    drawAnimation.duration            = 2.0; // "animate over 10 seconds or so.."
    drawAnimation.repeatCount         = 1.0;  // Animate only once..
    drawAnimation.removedOnCompletion = NO;   // Remain stroked after the animation..

    // Animate from no part of the stroke being drawn to the entire stroke being drawn
    drawAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
    drawAnimation.toValue   = [NSNumber numberWithFloat:1.0f];

    // Experiment with timing to get the appearence to look the way you want
    drawAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];

    drawAnimation.delegate = self;

    // Add the animation to the circle
    [circle addAnimation:drawAnimation forKey:@"drawCircleAnimation"];

}

还有以下代码：

-(void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag{
    CALayer *layer = [anim valueForKey:@"parentLayer"];
    NSLog(@"%@",layer);
    NSLog(@"%@",flag?@"YES":@"NO");
}

给出以下输出：

2013-07-02 19:28:14.760 TicTacToe[16338:707] (null)

2013-07-02 19:28:14.761 TicTacToe[16338:707] NO

更新：

在我用一个层( animationDidStop:... )支持视图( [view setWantsLayer:YES])之后，finished作为YES调用了该方法。但屏幕上仍然没有显示任何东西。

下面是从CGPathRef获取NSBezierPath的代码

- (CGPathRef)quartzPath
{
    int i;
    NSInteger numElements;

    // Need to begin a path here.
    CGPathRef           immutablePath = NULL;

    // Then draw the path elements.
    numElements = [self elementCount];
    if (numElements > 0)
    {
        CGMutablePathRef    path = CGPathCreateMutable();
        NSPoint             points[3];
        BOOL                didClosePath = YES;

        for (i = 0; i < numElements; i++)
        {
            switch ([self elementAtIndex:i associatedPoints:points])
            {
                case NSMoveToBezierPathElement:
                    CGPathMoveToPoint(path, NULL, points[0].x, points[0].y);
                    break;

                case NSLineToBezierPathElement:
                    CGPathAddLineToPoint(path, NULL, points[0].x, points[0].y);
                    didClosePath = NO;
                    break;

                case NSCurveToBezierPathElement:
                    CGPathAddCurveToPoint(path, NULL, points[0].x, points[0].y,
                                          points[1].x, points[1].y,
                                          points[2].x, points[2].y);
                    didClosePath = NO;
                    break;

                case NSClosePathBezierPathElement:
                    CGPathCloseSubpath(path);
                    didClosePath = YES;
                    break;
            }
        }

        // Be sure the path is closed or Quartz may not do valid hit detection.
        if (!didClosePath)
            CGPathCloseSubpath(path);

        immutablePath = CGPathCreateCopy(path);
        CGPathRelease(path);
    }

    return immutablePath;
}

我使用的是10.7SDK，不能使用内置的CGPath方法，该方法添加了新的NSBezierPath SDK。

Answer 1

默认情况下，OS上的视图没有附加层，所以可能的问题是vcForCellView.view.layer是nil。这意味着形状层永远不会被添加到层层次结构中，所以当动画被添加到形状层时，它会立即被取消(正如finished是NO所看到的)。

您可以告诉您的视图，它应该由一个层支持，使用：[myView setWantsLayer:YES];