ios - 在动画过程中改变位置？

Question

我有一个uit_code大小的UIImageView。我想将其尺寸设置为8x8。它工作正常。但是，当我从动画外部更改point1(touchPositionInView)的位置时，它不会更新，而是从触摸开始的原始位置进行动画处理。有没有什么办法解决这一问题？

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [UIView beginAnimations:@"widen" context:nil];
    [UIView setAnimationDuration:1.0];
    CGRect newRect = yellow.frame;
    newRect.size.height = 8;
    newRect.size.width = 8;
    yellow.center = point1;
    yellow.frame = newRect;
    [UIView commitAnimations];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    point1 = [touch locationInView:View];
}

Answer 1

您的问题是touchesBegan:withEvent:仅被调用一次，而touchesMoved:withEvent:在每次移动中均被调用。

我建议您也在touchesMoved:withEvent:方法中添加一个动画块。 :-)

存储point1并将图像大小调整为8、8，然后开始位置动画。

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    point1 = [touch locationInView:View];

    [UIView beginAnimations:@"widen" context:nil];
    [UIView setAnimationDuration:1.0];
    CGRect newRect = yellow.frame;
    newRect.size = CGSizeMake(8, 8);
    yellow.frame = newRect;
    [self updatePoint:NO];
    [UIView commitAnimations];
}

每次移动时更新位置并开始位置动画。

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    point1 = [touch locationInView:View];
    [self updatePoint:YES];
}

做位置动画。

- (void)updatePoint:(BOOL)animated
{

    // I think it would be an approvement, if you calculate the duration by the distance from the
    // current point to the target point
    if (animated)
    {
        yellow.center = point1;
    }
    else
    {
        [UIView animateWithDuration:1.0
                              delay:0
                            options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionAllowAnimatedContent
                         animations:^{
                             yellow.center = point1;
                         }
                         completion:^(BOOL finished){}
        ];
    }
}