Iphone SDK：移动并旋转触摸

Question

我有一条鱼的图像 - 如果用户触摸屏幕，我希望鱼“看”在触摸点，并在那里移动。如果触摸已经移动，我希望鱼不断跟随触摸。

我该怎么做？

Answer 1

会是这样的：

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *tap = [touches anyObject]; 
    CGPoint pointToMove = [tap locationInView:self.view]; 

    CGFloat xdiff = pointToMove.x-myFish.center.x; 
    CGFloat ydiff = pointToMove.y-myFish.center.y; 

    if (!CGRectContainsPoint(myFish.frame, pointToMove)) { 
     CGFloat angle = 0; 
     if (xdiff) { 
      if (xdiff>0) { 
       angle = atanf(ydiff/xdiff); 
      } else { 
       angle = M_PI + atanf(ydiff/xdiff); 
      } 
     } 
     [UIView beginAnimations:nil context:NULL]; 
     [UIView setAnimationDuration:0.3f]; 
     [UIView setAnimationBeginsFromCurrentState:YES]; 
     [UIView setAnimationCurve:UIViewAnimationCurveLinear];   
     myFish.transform = CGAffineTransformMakeRotation(angle); 
     [UIView commitAnimations]; 
    } 

    [UIView beginAnimations:nil context:NULL]; 
    [UIView setAnimationDuration:1.0f]; 
    [UIView setAnimationBeginsFromCurrentState:YES]; 
    [UIView setAnimationCurve:UIViewAnimationCurveLinear];  
    myFish.center = pointToMove; 
    [UIView commitAnimations]; 
} 

，你也只需要实施这些：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 

编辑：更新的代码，现在旋转在一个单独的动画完成，这样鱼的转动速度比他游泳的速度快。