label 添加虚线边框

CAShapeLayer *border = [CAShapeLayer layer];

border.strokeColor = SLColorLine.CGColor;

border.fillColor = nil;

border.path = [UIBezierPath bezierPathWithRect:self.bounds].CGPath;

border.frame = self.bounds;

border.lineWidth = 1.f;

border.lineCap = @"square";

border.lineDashPattern = @[@4, @2];

[self.layer addSublayer:border];