如何在iPhone-OS中终止正在运行的动画？

Question

我有一个类"Cube",并且有一个方法-rotate.该方法将anchorPoint设置在左下角,然后将立方体旋转90度.之后,调用另一种方法,使立方体向后旋转-90度.这已经完成了指定停止选择器.顺便说一下:这没什么特别的.刚刚学习!

-rotate在触摸事件时被调用.但是现在,当立方体对象仍在旋转时,假设它当前处于33.943 ......,用户可能会在该动画结束之前再次触摸事件.

然后,该触摸事件将立即再次调用-rotate方法.会发生的是,转换重叠并且立方体图像完全伸展和变形.

因此,在新动画开始之前,当前正在运行的动画必须停止.

UPDATE

在我开始动画之前,我称之为:

- (void)resetAnimation {
    self.layer.transform = CATransform3DIdentity; // reset the transform to the identity transform ("no rotation applied, please")
    [Cube setAnimationDelegate:nil];
    [Cube setAnimationDidStopSelector:NULL];
}

另外,我设置了[Cube setAnimationBeginsFromCurrentState:YES]; 我开始动画块的地方.

因此,当动画从外部进入时,它将如下所示:(注意,屏幕上有5个此类的对象,可以踢到动画)

- (void)kickAnimation { // if that's called, the cube gets a kick to rotate
    self.layer.transform = CATransform3DIdentity;
    currentDegrees = 90; // just testing! it may also be negative
    NSString *animID = [NSString stringWithFormat:@"cube_%i",self.datasetID];
    if (currentDegrees > 0) {
        [self rotateRight:animID finished:0 context:self];
    } else if (currentDegrees < 0) {
        [self rotateLeft:animID finished:0 context:self];
    }
}

- (void)rotateRight:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
    // 1) here the anchorPoint is set to the lower right corner
    // 2) here the view's frame is repositioned so that the cube doesn't move visually after the anchorPoint changed
    [self rotateByDegrees:currentDegrees animationID:animationID];
}

- (void)rotateByDegrees:(CGFloat)degrees animationID:(NSString *)animationID {
    [Cube beginAnimations:animationID context:self];
    [Cube setAnimationDelegate:self];
    [Cube setAnimationDidStopSelector:@selector(rotateBack:finished:context:)];
    [Cube setAnimationDuration:2.1f];
    [Cube setAnimationBeginsFromCurrentState:YES];
    CATransform3D rotatedTransform = self.layer.transform;
    rotatedTransform = CATransform3DRotate(rotatedTransform, degrees * M_PI / 180.0, 0.0f, 0.0f, 1.0f);
    self.layer.transform = rotatedTransform;
    [UIView commitAnimations];
}

- (void)rotateBack:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
    currentDegrees *= -1;
    [Cube beginAnimations:animationID context:self];
    self.layer.transform = CATransform3DIdentity;
    [Cube setAnimationDelegate:nil];
    [Cube setAnimationDidStopSelector:NULL];
    [Cube setAnimationDuration:2.1f];
    [Cube setAnimationBeginsFromCurrentState:YES];
    CATransform3D rotatedTransform = self.layer.transform;
    rotatedTransform = CATransform3DRotate(rotatedTransform, currentDegrees * M_PI / 180.0, 0.0f, 0.0f, 1.0f);
    self.layer.transform = rotatedTransform;
    currentDegrees = 0;
    [UIView commitAnimations];
}

现在它几乎可以工作了.如果动画启动重叠,立方体不会再变形.但有一点是错误的:如果一个新的"踢"进来,并且立方体当前正在向后旋转,它应该立即开始向右旋转.但碰巧它首先旋转然后识别出"踢",这看起来很奇怪;)

Answer 1

这是一个类似的问题和答案.

如果您调用[UIView setAnimationBeginsFromCurrentState:YES];新动画将从视图所在位置开始并停止上一个动画.