Core Animation 学习笔记

最新推荐文章于 2021-12-07 01:00:00 发布

翻译最新推荐文章于 2021-12-07 01:00:00 发布 · 873 阅读

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#Core Animation

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本文介绍如何使用CABasicAnimation在iOS应用中实现箭头视图的旋转和颤动效果，包括旋转45度的动画及左右颤动重复动画的具体实现。

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- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    _arrow = [[Arrow alloc]initWithFrame:CGRectMake(0, 0, 40, 100)];
    _arrow.opaque = NO;
    _arrow.center = self.view.center;
    [self.view addSubview:_arrow];
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
    button.frame = CGRectMake(120, 60, 80, 30);
    [button setTitle:@"rotate" forState:UIControlStateNormal];
    button.backgroundColor = [UIColor redColor];
    [button addTarget:self action:@selector(vibrateArrowRepeat) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

// 使用 CABasicAnimation
//通过动画的方式使罗盘的箭头旋转45度
-(void)rotateArrow
{
// capture the start and end values
   /* 1. CATransform3D startValue = _arrow.layer.transform;
    CATransform3D endValue =
        CATransform3DRotate(startValue, M_PI/4.0, 0, 0, 1);
    //change the layer, without implicit animation
    [CATransaction setDisableActions:YES];
    _arrow.layer.transform = endValue;
    //construct the explicit animation
    CABasicAnimation *anim =
    [CABasicAnimation animationWithKeyPath:@"transform"];
    anim.duration = 0.8;
    CAMediaTimingFunction *clunk =
    [CAMediaTimingFunction functionWithControlPoints:.9 :.1 :.7 :.9];
    anim.timingFunction = clunk;
    anim.fromValue = [NSValue valueWithCATransform3D:startValue];
    anim.toValue = [NSValue valueWithCATransform3D:endValue];
    //ask for the explicit animation
    [_arrow.layer addAnimation:anim forKey:nil];*/
    
    /*2.  实际上上面的代码可以简化
    例如，当fromValue和toValue没有被设置时，之前和当前的属性值会被自动使用。
     这是由于，presentation layer仍然保留了之前的属性值，而当前的layer已经有了新的值
     简化为如下代码:
     */
    
    [CATransaction setDisableActions:YES];
    _arrow.layer.transform =
    CATransform3DRotate(_arrow.layer.transform, M_PI/4.0, 0, 0, 1);;
    CABasicAnimation *anim =
    [CABasicAnimation animationWithKeyPath:@"transform"];
    anim.duration = 0.8;
    CAMediaTimingFunction *clunk =
    [CAMediaTimingFunction functionWithControlPoints:.9 :.1 :.7 :.9];
    anim.timingFunction = clunk;
    [_arrow.layer addAnimation:anim forKey:nil];
}

//现在我们让箭头左右颤动
-(void)vibrateArrowRepeat
{
  /*  1.CATransform3D nowValue = _arrow.layer.transform;
    CATransform3D startValue =
    CATransform3DRotate(nowValue, M_PI/40.0, 0, 0, 1);
    CATransform3D endValue =
    CATransform3DRotate(nowValue,- M_PI/40.0, 0, 0, 1);
    //change the layer, without implicit animation
    [CATransaction setDisableActions:YES];
    _arrow.layer.transform = endValue;
    //construct the explicit animation
    CABasicAnimation *anim =
    [CABasicAnimation animationWithKeyPath:@"transform"];
    anim.duration = 0.05;
    anim.timingFunction =
    [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    anim.repeatCount =  3;
    anim.autoreverses = YES;
    anim.fromValue = [NSValue valueWithCATransform3D:startValue];
    anim.toValue = [NSValue valueWithCATransform3D:endValue];
    //ask for the explicit animation
    [_arrow.layer addAnimation:anim forKey:nil];*/
    /* 2.我们可以基于arrow的当前的transform，通过设置animation的additive值为YES
     来计算新的rotation的值。这意味着加到animation的属性值是相对的而不是绝对的值
     我们不需要依赖arrow当前的rotation，CAValueFunction告诉animation沿着z轴旋转
     */
    CABasicAnimation *anim =
    [CABasicAnimation animationWithKeyPath:@"transform"];
    anim.duration = 0.05;
    anim.timingFunction =
    [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    anim.repeatCount =  3;
    anim.autoreverses = YES;
    anim.additive = YES; //
    anim.valueFunction =
    [CAValueFunction functionWithName:kCAValueFunctionRotateZ];
    anim.fromValue = @(M_PI/40);
    anim.toValue = @(-M_PI/40);
    //ask for the explicit animation
    [_arrow.layer addAnimation:anim forKey:nil];
    
    /*
     需要注意的是，这里没有@“frame”key，如果要用一个layer的frame产生动画，position和bounds 都要改变
     例子：where outer is the superview of inner,and inner expands to fill the width of outer
     CABasicAnimation *anim1 =
     [CABasicAnimation animationWithKeyPath:@"bounds"];
     //...omit the change of frame
     self.innser.layer.bounds = f;
     [self.inner.layer addAnimation:anim1 forKey:nil];
     
     CABasicAnimation *anim2 =
     [CABasicAnimation animationWithKeyPath:@"position"];
     //...omit the change of position
     self.inner.layer.position = p;
      [self.inner.layer addAnimation:anim2 forKey:nil];
     */
}