如何让视图永远旋转？ [英] How to let a view rotate forever?

问题描述

有没有办法让视图以指定的速度永远旋转？我需要一个指标类型的东西。我知道有一个奇怪的Lxxxxx00ff常数（完全不记得它）代表永远。

Is there a way to let a view rotate forever, with an specified speed? I need that for an indicator kind of thing. I know there is this weird Lxxxxx00ff constant (don't remember it exactly) that stands for "forever".

推荐答案

你可以使用 HUGE_VAL 获取浮动值（如果我没记错的话，动画的repeatCount属性是浮点数）。

You can use HUGE_VAL for floating value (if I remember correctly, repeatCount property for animation is a float).

要设置动画，您可以使用 + animationWithKeyPath创建CAAnimation对象：方法：

To setup animation you can create CAAnimation object using +animationWithKeyPath: method:

CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
animation.fromValue = [NSNumber numberWithFloat:0.0f];
animation.toValue = [NSNumber numberWithFloat: 2*M_PI];
animation.duration = 3.0f;
animation.repeatCount = HUGE_VAL;
[rotView.layer addAnimation:animation forKey:@"MyAnimation"];

如果我记得使用UIView正确创建这种旋转动画是不可能的，因为旋转360度（ 2 * M_PI弧度）被优化为完全没有旋转。

If I remember correctly creating this kind of rotation using just UIView animations is impossible because rotations on 360 degrees (2*M_PI radians) are optimized to no rotation at all.

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