How can i take an UIImage and give it a black border programmatically?

Question

How can i take an UIImage and give it a black border programmatically?

If i can receive code, it will be great.

tnx

Answer 1

I'd have a look at this: Can I Edit the Pixels of the UIImage's Property CGImage

As for the black border part, I assume you can figure that one out. Just iterate along each side and change the pixels to (0,0,0,255) for a certain amount.

Answer 2

If you only need to display the border you can do that with Core Animation on the UIImageView's layer. If you need to do it on the image itself then you will need to create a new image, draw the old image into the new image and then draw a rect on top of it.

- (UIImage*)imageWithBorderFromImage:(UIImage*)source;
{
  CGSize size = [source size];
  UIGraphicsBeginImageContext(size);
  CGRect rect = CGRectMake(0, 0, size.width, size.height);
  [source drawInRect:rect blendMode:kCGBlendModeNormal alpha:1.0];

  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextSetRGBStrokeColor(context, 1.0, 0.5, 1.0, 1.0); 
  CGContextStrokeRect(context, rect);
  UIImage *testImg =  UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return testImg;
}

This will put a pink border on an image and return the new image.