带有自定义图像的活动指示器

问题描述

我正在加载一个 UIWebView，同时我不想用这个显示一个空白页面 活动指示器旋转(siri 活动指示器).据我了解，您不能更改图像，但我不能使用该图像并创建一个旋转 360° 并循环播放的动画吗?还是会耗尽电池?

I am loading a UIWebView and in the meantime I wan't to show a blank page with this activity indicator spinning (siri activity indicator). From what I have understand you can not change the image, but can't I use that image and create an animation with it rotating 360° and looping? Or will that drain the battery?

像这样?:

- (void)webViewDidStartLoad:(UIWebView *)webView {
    //set up animation
    [self.view addSubview:self.loadingImage];
    //start animation
}

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    //stop animation
    [self.loadingImage removeFromSuperview];
}

我该怎么办?

提前致谢！

推荐答案

大部分都可以在 Stack Overflow 中找到.让我总结一下:

Most of this is found in Stack Overflow. Let me summarize:

创建一个用作活动指示器的 UIImageView(在情节提要场景、NIB、代码......任何你想要的地方).我们称之为 _activityIndi​​catorImage

Create an UIImageView which will serve as an activity indicator (inside storyboard scene, NIB, code ... wherever you wish). Let's call it _activityIndicatorImage

加载你的图片:_activityIndi​​catorImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"activity_indicator"]];

您需要使用动画来旋转它.这是我使用的方法:

You need to use animation to rotate it. Here is the method I use:

+ (void)rotateLayerInfinite:(CALayer *)layer
{
    CABasicAnimation *rotation;
    rotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    rotation.fromValue = [NSNumber numberWithFloat:0];
    rotation.toValue = [NSNumber numberWithFloat:(2 * M_PI)];
    rotation.duration = 0.7f; // Speed
    rotation.repeatCount = HUGE_VALF; // Repeat forever. Can be a finite number.
    [layer removeAllAnimations];
    [layer addAnimation:rotation forKey:@"Spin"];
}

在我的 layoutSubviews 方法中，我启动了旋转.如果这更适合您的情况，您可以将其放在 webViewDidStartLoad 和 webViewDidFinishLoad 中:

Inside my layoutSubviews method I initiate rotation. You could place this in your webViewDidStartLoad and webViewDidFinishLoad if this is better for your case:

- (void)layoutSubviews
{
    [super layoutSubviews];

    // some other code

    [Utils rotateLayerInfinite:_activityIndicatorImage.layer];
}

您总是可以使用 [_activityIndi​​catorImage.layer removeAllAnimations];

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