ios - 贝塞尔路径在 View 中不可见

Question

我从斯坦福 ios7 类(class)中复制了以下代码，用于向 View 添加贝塞尔曲线路径。然而，当我将此代码包含在 ViewDidLoad 中时，它没有在屏幕上显示任何内容

 UIBezierPath *path = [[UIBezierPath alloc] init];
    [path moveToPoint:CGPointMake(75, 10)];
    [path addLineToPoint: CGPointMake(160, 150)];
    [path addLineToPoint:CGPointMake(10, 150)];
    [[UIColor whiteColor] setStroke];
    [[UIColor whiteColor] setFill];
    [path stroke];
    [path fill];

之后，我添加了这个日志语句 NSLog(@"path: %@", path); 打印了这个不祥的错误消息。

This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

你能解释一下我做错了什么吗？

Answer 1

我通过创建一个 CAShapeLayer 并将其添加为 View 层的子层来完成此操作。巧妙的是，您可以使用 UIBezierPath 的 CGPath 属性来设置图层。

    CAShapeLayer *layer = [CAShapeLayer layer];
    layer.path = path.CGPath;
    layer.strokeColor = [UIColor whiteColor].CGColor;
    [self.view.layer addSublayer:layer];