检查某个位置是否已存在对象

Question

我想检查一下屏幕上某个特定位置是否有物体。我有一个带有框架（7,545,75,75）的图像视图和另一个移动的图像视图。我不希望它能够移动到与其他图像视图相同的位置，因此我需要能够判断对象是否存在于我试图移动到的位置。

以下是我的动态影像视图代码：

- (IBAction)moveForward:(id)sender
{
    moveForwardCards--;
    forwardLabel.text = [NSString stringWithFormat:@"%i left", moveForwardCards];

    if (moveForwardCards == 0)
    {
        forwardButton.enabled = NO;
    }

    if (turtle.image.imageOrientation == UIImageOrientationRight)
    {
        turtle.frame = CGRectMake(turtle.frame.origin.x, turtle.frame.origin.y + 90, 75, 75);
    }
    else if (turtle.image.imageOrientation == UIImageOrientationLeft)
    {
        turtle.frame = CGRectMake(turtle.frame.origin.x, turtle.frame.origin.y - 90, 75, 75);
    }
    else if (turtle.image.imageOrientation == UIImageOrientationUp)
    {
        turtle.frame = CGRectMake(turtle.frame.origin.x + 90, turtle.frame.origin.y, 75, 75);
    }
    else if (turtle.image.imageOrientation == UIImageOrientationDown)
    {
        turtle.frame = CGRectMake(turtle.frame.origin.x - 90, turtle.frame.origin.y, 75, 75);
    }

    NSLog(@"turtle frame: %@", NSStringFromCGRect(turtle.frame));
}