iphone - 在动画中切换位置属性上的 CABasicAnimation 会导致闪烁

Question

我有一些代码使用 CALayers 使气泡从下到上流动。如果用户触摸屏幕，我会编写一些代码，将当前正在运行的动画替换为具有手指触摸的 toPoint 的动画。当动画切换时，它会导致设备上(而不是模拟器上)闪烁。任何有关消除闪烁的提示将不胜感激!谢谢。

在层本身内部向上流动的气泡的代码:

CABasicAnimation *animation = [CABasicAnimationanimationWithKeyPath:@"position"];
[animation setDelegate:self];
CGPoint position = [self position];
NSValue *prevVal = [NSValue valueWithCGPoint:position];
[animation setFromValue:prevVal];
CGPoint toPoint = CGPointMake(position.x,-100);
[animation setToValue:[NSValue valueWithCGPoint:toPoint]];
[animation setDuration:animationDuration];
[self addAnimation:animation forKey:@"flow"];

super 层中编写的吸引附近气泡到触摸点的代码:

int count = [self.layer.sublayers count];
for(int i = 0; i < count ; i++) {
   CALayer *layer= [self.layer.sublayers objectAtIndex:i];
   CALayer *p = (CALayer*)[layer presentationLayer];
   CGPoint position = [p position];

   if(abs(position.x - touchPoint.x) < 100 && abs(position.y - touchPoint.y) < 100) {

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position"];
    [animation setDelegate:self];
    NSValue *prevVal = [NSValue valueWithCGPoint:position];
    [animation setFromValue:prevVal];
    [animation setToValue:[NSValue valueWithCGPoint:touchPoint]];
    [animation setDuration:2.0];
    [animation setTimingFunction:[CAMediaTimingFunction  
            functionWithName:kCAMediaTimingFunctionEaseOut]];
    [layer addAnimation:animation forKey:@"flow"];
   }        

}

Answer 1

尝试在更新周围使用 CATransaction 锁，看看是否有帮助。当您使用新动画更新图层时，这将防止以前的动画更改图层的位置。

在您的触摸处理方法中，将动画包装在事务中并锁定:

[CATransaction lock];
[CATransaction begin];

// update the sublayers with new animations

[CATransaction commit];
[CATransaction unlock];