以按钮为例子，实现虚线按钮：

    CAShapeLayer *border = [CAShapeLayer layer];
    //虚线的颜色
    border.strokeColor = [UIColor colorWithHexString:@"#333333"].CGColor;
    //填充的颜色
    border.fillColor = [UIColor clearColor].CGColor;
    //设置路径
     border.path = [UIBezierPath bezierPathWithRect:self.clickUploadBtn.bounds].CGPath;
    border.frame = self.clickUploadBtn.bounds;
    //虚线的宽度
    border.lineWidth = 1.f;
    //设置线条的样式
    //    border.lineCap = @"square";
    //虚线的间隔
    border.lineDashPattern = @[@4, @2];
    [self.clickUploadBtn.layer addSublayer:border];

image.png

到这里基本已经OK了，但是突然发现我要的是有圆角的按钮，那就去添加圆角

        btn.layer.cornerRadius = 15;
        btn.clipsToBounds = YES;

然而效果是这样子的，四个角变的很奇怪

image.png

最后找资料终于得到实现效果 需要把bezierPathWithRect 替换成 bezierPathWithRoundedRect 就可以了

    CAShapeLayer *border = [CAShapeLayer layer];
    //虚线的颜色
    border.strokeColor = [UIColor colorWithHexString:@"#333333"].CGColor;
    //填充的颜色
    border.fillColor = [UIColor clearColor].CGColor;
    //设置路径
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:self.clickUploadBtn.bounds cornerRadius:15];
    border.path = path.CGPath;
    border.frame = self.clickUploadBtn.bounds;
    //虚线的宽度
    border.lineWidth = 1.f;
    //设置线条的样式
    //    border.lineCap = @"square";
    //虚线的间隔
    border.lineDashPattern = @[@4, @2];
    [self.clickUploadBtn.layer addSublayer:border];

最终效果：

image.png