Question

我有以下代码：

- (void)setupLayer {
    self.faucetShape = [CAShapeLayer layer];
    self.faucetShape.strokeColor = [[UIColor blackColor] CGColor];
    self.faucetShape.lineWidth = 2;
    self.faucetShape.fillColor = nil;
    self.faucetShape.path = [self faucetPath].CGPath; // faucetPath returns a 4 point diamond shaped UIBezierPath*
    self.faucet = [CAGradientLayer layer];
    self.faucet.mask = self.faucetShape;
    self.faucet.colors = @[(id)[UIColor redColor].CGColor, (id)[UIColor redColor].CGColor];
    [self.layer addSublayer: self.faucet];
}

但它没有显示任何内容。不知道我错过了什么（除了我的图片）。

（faucet和faucetPath都是属性）

更新

好的，我想CAGradientLayer必须有一个有意义的frame。我认为CAShapeLayer的{{1}}没有意义，因为frame可以超出path。添加以下行使其显示：

frame

所以现在我的问题是，有没有办法避免不必这样做？我只是喜欢图层的框架隐含的是包含视图/图层的框架。

Answer 1

您需要设置图层的框架。以下代码将绘制一个红色圆圈：

- (void)setupLayer
{
    CAShapeLayer *faucetShape = [CAShapeLayer layer];
    faucetShape.frame = CGRectMake(0, 0, 100, 100);
    faucetShape.strokeColor = [[UIColor blackColor] CGColor];
    faucetShape.lineWidth = 2;
    faucetShape.fillColor = nil;
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddEllipseInRect(path, nil, CGRectMake(0, 0, 100, 100));
    faucetShape.path = path;
    CGPathRelease(path);
    CAGradientLayer *faucet = [CAGradientLayer layer];
    faucet.frame = CGRectMake(10, 10, 100, 100);
    faucet.mask = faucetShape;
    faucet.colors = @[(id)[UIColor redColor].CGColor, (id)[UIColor redColor].CGColor];
    [self.view.layer addSublayer: faucet];
}

带有CAShapeLayer掩码的CAGradientLayer未显示

1 个答案: