Setting multiple borders on UIView

问题:

As I cannot find any questions/answers for this, I imagine it is not possible.

Is there anyway to set multiple borders on a UIView.

I am currently setting a standard border with .layer.borderWidth and layer.borderColor. I am wondering if I can add a multiple strokes/borders effect to the view.

I need a border of 4.0f in white then another 1.0f in another color.

回答1:

Three solutions I can think of:

• nest a UIView in another one, define one border for each;
• draw the border yourself in -(void)drawRect;
• use an UIImageView with a resizable; stretchable image of your borders as background (the best solution performance-wise).

回答2:

That isn't possible with a single UIView instance without adding layers.

What you can do is create a view that is larger than necessary, set its border appropriately, then add a CALayer and position it where you want the inner border and set its border properties appropriately.

Using CALayers is typically faster than full blown UIView, but you can also just have a nested UIView to achieve the same effect.

回答3:

This is not possible, you will have to fake borders by adding UIView's with a background color to your xib/view.

回答4:

Try this,

I'm adding shadow with alpha 1 which will act as the inner border. And the normal border is given as outer border.

yourView.frame = CGRectInset(yourView.frame, -borderWidth, -borderWidth);
yourView.layer.borderColor = [UIColor blackColor].CGColor;
yourView.layer.borderWidth = borderWidth;


yourView.layer.shadowColor = [UIColor whiteColor].CGColor;
yourView.layer.shadowOffset = CGSizeMake(0, 1);
yourView.layer.shadowOpacity = 1;
yourView.layer.shadowRadius = 1.0;
yourView.clipsToBounds = YES;

回答5:

You can insert two layers of different widths using this extension:

extension CALayer {
    func addGradientBorder(colors:[UIColor],width:CGFloat = 1) {
        let gradientLayer = CAGradientLayer()
        gradientLayer.frame =  CGRect(origin: CGPoint.zero, size: self.bounds.size)
        gradientLayer.startPoint = CGPoint(x:0.0, y:0.0)
        gradientLayer.endPoint = CGPoint(x:1.0,y:1.0)
        gradientLayer.colors = colors.map({$0.cgColor})

        let shapeLayer = CAShapeLayer()
        shapeLayer.lineWidth = width
        shapeLayer.path = UIBezierPath(rect: self.bounds).cgPath
        shapeLayer.fillColor = nil
        shapeLayer.strokeColor = UIColor.red.cgColor
        gradientLayer.mask = shapeLayer

        self.addSublayer(gradientLayer)
    }
}

Use this with different widths/colors to get the desired effect:

yourView.layer.addGradientBorder(colors:[UIColor.black,UIColor.black] , width: 20)
yourView.layer.addGradientBorder(colors:[UIColor.white,UIColor.white] , width: 10)

Output looks like the following image with outer white border and inner black border: