iOS中的透明环 [英] Transparent Ring in iOS

问题描述

我的视线中有一个圆形的头像.我是这样的:

I have a circle avatar on my view. I make it like this:

self.imageView.layer.cornerRadius = 75;
self.imageView.layer.masksToBounds = YES;
self.imageView.layer.borderWidth = 1;
self.imageView.layer.borderColor = [UIColor whiteColor].CGColor;

但是我想要头像和白色边框之间的透明2px环.我无法在背景上绘制白色圆圈，因为化身可以移动并且戒指位置也会丢失.我的想法是使用

But I want transparent 2px ring between avatar and white border. I can't draw a white circle on the background, because the avatar can move and ring position will be lost. I have the idea to stroke path using

CGContextSetBlendMode(context, kCGBlendModeClear);

在分配了层之后，但是我没有发现它到底是怎么做到的.感谢您的帮助.

after assigning the layer, but I don't catch how exactly do it. Appreciate for your help.

推荐答案

该问题似乎只是缺乏想象力的问题.

that question seems to be a lack-of-imagination issue only.

在 Interface Builder 中，您需要添加一个容器视图，并且该视图包含化身图像视图；这是它在我的屏幕上的外观的原始图片，在编辑器中的视图:

in the Interface Builder, you need to add a container view and that view holds the avatar image view; it is the raw picture of how it look on my screen the view in the editor:

这是视图层次结构中两个视图之间的关系:容器视图是头像图像视图的超级视图:

that is the relationship between the two views in the view hiearchy: the container view is the superview of the avatar image view:

在将相关的插座(分别称为_containerView和_avatarImageView)添加到类并将它们连接到视图之后；我们还可以将此小片段添加到我们的代码中:

after adding the related outlets (call them _containerView and _avatarImageView) to the class and conntected them to the views; we also can add this little snippet to our code:

[_containerView setBackgroundColor:[UIColor clearColor]];
[_containerView.layer setCornerRadius:MIN(_containerView.bounds.size.width, _containerView.bounds.size.height) / 2.0];
[_containerView.layer setBorderColor:[[UIColor whiteColor] CGColor]];
[_containerView.layer setBorderWidth:4.0];

[_avatarImageView.layer setCornerRadius:MIN(_avatarImageView.bounds.size.width, _avatarImageView.bounds.size.height) / 2.0];
[_avatarImageView.layer setMasksToBounds:TRUE];

在模拟器或真实设备violá上运行项目后，透明环出现在图像和边框之间:

and after running the project on the simulator or a real device, violá, the transparent ring appears between the image and the border:

注意:透明环的实际大小取决于化身比容纳它的容器视图小多少.重要的！我不知道女孩是谁，请不要问我她的电话号码.

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