ios - iOS Draw a line above label

Question

I have a label in my view. Now I want to draw a line above the label, which means you can see the label is under the line.

So far I can draw a line using quartz2D but always under the label. Is there any way to solve my problems?

Answer 1

您可以创建一个CAShapeLayer这样的：

CAShapeLayer *lineLayer = [CAShapeLayer layer];
lineLayer.frame = self.label.bounds;
lineLayer.strokeColor = [UIColor redColor].CGColor;

CGRect rect = CGRectMake(0, CGRectGetMidY(lineLayer.bounds), lineLayer.bounds.size.width, 2);
lineLayer.path = [UIBezierPath bezierPathWithRect:rect].CGPath;

然后将它添加到UILabel这样的：

[self.label.layer addSublayer:lineLayer];

Answer 2

老实说，最简单的做法是创建一个名为 line@2x.png 的 2x2 像素图像，将底部 2 个像素设置为黑色，顶部 2 个透明，然后将其用作图像视图的背景图像。通过将图像视图用作图案图像，将图像视图拉伸到您需要的任何宽度。1x 图像应该是 1x1px，全黑。

UIView *lineView = [[UIView alloc] initWithFrame:frame]; // Whatever frame the line needs

// Add the line image as a pattern
UIColor *patternColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"line.png"]];
lineView.backgroundColor = patternColor;
[self.view addSubview:lineView];

Answer 3

如果这是一个你会经常使用的标签，你可以创建一个 UILabel 的子类并覆盖 drawRect 函数。

- (void) drawRect:(CGRect)r
{
    [super drawRect:r];

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);
    CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
    CGContextSetLineWidth(context, 1.0);
    CGContextMoveToPoint(context, 1.0, 1.0);
    CGContextAddLineToPoint(context, self.bounds.size.width - 1.0, 1.0);
    CGContextStrokePath(context);
    CGContextRestoreGState(context);
}

这里的优点是线将被“烘焙”到视图中并且只绘制一次。其他方法如 CAShapeLayer 或 UIView 将每帧重新渲染。

对于奖励积分，您可以制作颜色和线宽属性:)