相关疑难解决方法(0)

我CABasicAnimation在视图中无休止地循环重复图像块:

a = [CABasicAnimation animationWithKeyPath:@"position"];
a.timingFunction = [CAMediaTimingFunction 
                      functionWithName:kCAMediaTimingFunctionLinear];
a.fromValue = [NSValue valueWithCGPoint:CGPointMake(0, 0)];
a.toValue = [NSValue valueWithCGPoint:CGPointMake(image.size.width, 0)];
a.repeatCount = HUGE_VALF;
a.duration = 15.0;
[a retain];

我已尝试按照技术问答QA1673中的描述"暂停并恢复"图层动画.

当应用程序进入后台时,动画将从图层中删除.为了补偿我听UIApplicationDidEnterBackgroundNotification,打电话stopAnimation和回应UIApplicationWillEnterForegroundNotification电话startAnimation.

- (void)startAnimation 
{
    if ([[self.layer animationKeys] count] == 0)
        [self.layer addAnimation:a forKey:@"position"];

    CFTimeInterval pausedTime = [self.layer timeOffset];
    self.layer.speed = 1.0;
    self.layer.timeOffset = 0.0;
    self.layer.beginTime = 0.0;
    CFTimeInterval timeSincePause = 
      [self.layer convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
    self.layer.beginTime = timeSincePause;
}

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