在iPhone SDK上实现动画的最佳方法？

Question

我知道如何通过移动/调整UIView来实现基本的动画。然而，下面两个动画似乎有点复杂。

1)想象一个汽车游戏，当你按下踏板按钮时，速度表旋转。如何制作那种条形“填充”成圆形的动画？

2)第二个动画更容易描述。如何做动画的数字增加，在那里的数字滑落和新的数字出现在顶部类似于老虎机。

Answer 1

对于你的第一个问题，我认为CGAffineTransform是最好的选择。用这个，我想像这样的东西可以起作用：

// BarView is a derived class from UIView that knows how to draw a "bar"
BarView view[NumBars];
for(int i = 0; i < NumBars; i++)
{
  // First place the view at the center of the instrument
  [view[i] setCenter:CGPointMake(InstrumentX, InstrumentY)];

  // Now translate the view InstrumentWidth units on the positive X-Axis
  CGAffineTransform translate = CGAffineTransformMakeTranslation(InstrumentWidth, 0);

  // Rotate the view about the origin by an angle related to which "bar" this is
  CGAffineTransform rotate = CGAffineTransformMakeRotation(i*AngleBetweenBars);

  // create a transform matrix from the translation and rotation matrices and apply it to the view
  [view[i] setTransform:CGAffineTransformConcat(translate, rotate)];   
}