围绕锚点问题旋转 UIImageView

Question

我正在尝试围绕锚点旋转 UIImageView 以模拟 "radar sweep" 样式的动画。我对锚点的理解使我相信 (1, 1) 应该是 radar image. However, setting the ImageView's anchor point to this doesn't give me the behavior I anticipated. This can be viewed here.

的右下角

可以看出，锚点位于图像右侧的上方，但它恰好位于中心。我想要的是围绕中心点旋转的图像，就像雷达扫描一样。

相关代码如下：

self.radarView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, barDimension, barDimension)];
self.radarView.contentMode = UIViewContentModeScaleAspectFill;
self.radarView.image = [UIImage imageNamed:@"radarSweep.png"];
self.radarView.layer.anchorPoint = CGPointMake(1, 1);
self.radarView.layer.position = CGPointMake(screenWidth / 2.0, screenHeight / 2.0);
[self.mapView addSubview:self.radarView];

CABasicAnimation *opacityInAnim = [CABasicAnimation animationWithKeyPath:@"opacity"];
[opacityInAnim setFromValue:[NSNumber numberWithFloat:0.0]];
[opacityInAnim setToValue:[NSNumber numberWithFloat:1.0]];
opacityInAnim.duration = 0.25;
opacityInAnim.fillMode = kCAFillModeForwards;
opacityInAnim.removedOnCompletion = NO;
opacityInAnim.beginTime = 0.0;
opacityInAnim.delegate = self;
[opacityInAnim setValue:@"radarSweep" forKey:@"animName"];

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
animation.fromValue = [NSNumber numberWithFloat:0.0];
animation.toValue = [NSNumber numberWithFloat:2 * M_PI];
animation.duration = 1.0f;
animation.fillMode = kCAFillModeForwards;
animation.repeatCount = 2;
animation.removedOnCompletion = NO;
[animation setBeginTime:0.0];
animation.delegate = self;
[animation setValue:@"radarSweep" forKey:@"animName"];
animation.removedOnCompletion = YES;

CABasicAnimation *opacityOutAnimBar = [CABasicAnimation animationWithKeyPath:@"opacity"];
[opacityOutAnimBar setFromValue:[NSNumber numberWithFloat:1.0f]];
[opacityOutAnimBar setToValue:[NSNumber numberWithFloat:0.0f]];
opacityOutAnimBar.delegate = self;
opacityOutAnimBar.fillMode = kCAFillModeForwards;
opacityOutAnimBar.removedOnCompletion = NO;
[opacityOutAnimBar setDuration:0.25];
[opacityOutAnimBar setValue:@"radarSweep" forKey:@"animName"];
[opacityOutAnimBar setBeginTime:1.35];

CAAnimationGroup *group = [CAAnimationGroup animation];
[group setDuration:2.0];
group.delegate = self;
group.fillMode = kCAFillModeForwards;
group.removedOnCompletion = NO;
[group setAnimations:@[opacityInAnim, animation, opacityOutAnimBar]];
[group setValue:@"radarSweep" forKey:@"animName"];
[self.radarView.layer addAnimation:group forKey:@"group"];

如有任何建议，我们将不胜感激。提前致谢。

Answer 1

您的雷达图像不是正方形，但 imageview 是正方形，因此图像超出了 imageView 的边界。您可以执行 self.radarView.layer.clipsToBounds = YES 或将内容模式更改为 ScaleToFit。或者您可以调整图像视图的大小以匹配雷达图像的比例。

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