在iOS中设置CALayer的“ borderWidth”和“ cornerRadius”，不能完全覆盖背景 [英] Set the CALayer 'borderWidth' and 'cornerRadius' in iOS, can not fully covers background

问题描述

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    self.yuanjiao.backgroundColor = [UIColor blackColor];
    self.yuanjiao.layer.cornerRadius = self.yuanjiao.frame.size.width/2;
    self.yuanjiao.layer.masksToBounds = YES;
    self.yuanjiao.layer.borderWidth = 5;
    self.yuanjiao.layer.borderColor = [UIColor colorWithRed:1 green:1 blue:1 alpha:1].CGColor;

    //    self.yuanjiao.layer.shadowOffset = CGSizeMake(0, 0);
    //    self.yuanjiao.layer.shadowRadius = 0.0;
    //    self.yuanjiao.layer.shadowColor = [UIColor whiteColor].CGColor;
    //    self.yuanjiao.layer.shadowOpacity = 0.0;
}

效果：

边界没有完全覆盖背景。

Border not fully cover the the background.

设置shadowxxx无效。

Setting shadowxxx has no effect.

推荐答案

这是图层属性的预期行为。如果您查看 Apple文档的 borderWidth 属性，您将找到：-

This is the intended behaviour of layer's property. If you look at Apple Documentation for borderWidth property, you will find: -

讨论

此值大于0.0时，图层将使用当前的borderColor值绘制边框。边框是根据此属性中指定的值从接收者的边界绘制的。 它在接收者的内容和子层之上进行了合成，并包含cornerRadius属性的效果。

此属性的默认值为0.0。 / p>

The default value of this property is 0.0.

如果您需要用<$ c $填充 borderWidth 部分c> blackColor ，那么您有两个选择

If you are in need to fill the borderWidth portion with blackColor as well, then you have two choices

1. 边框颜色没有意义与视图的内容没有什么不同。您将完全看不到边框。您将看到的是一个更大的圆圈，里面充满了 blackColor 。


2. 如果您想保留边框并且还需要用黑色填充颜色，然后将 borderColor 属性分配给 blackColor 。

1. There is no point in having a border whose color is not different than the content of view. You will not be able to see the border at all. All you will see is a little bigger circle filled with blackColor.
2. If you wanna keep border and also needs to fill it with black color then assign the borderColor property to blackColor.

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