ios - Add transparent space around a UIImage

Question

Lets say we have an image of 600X400 pixel and we want to end up with an new image of 1000x1000 pixel which contains the initial image in the centre and transparent space around it. How can I achieve that in code?

Answer 1

In Swift you can write an extension to UIImage that draws image with insets around it.

Swift 3:

import UIKit

extension UIImage {
    func imageWithInsets(insets: UIEdgeInsets) -> UIImage? {
        UIGraphicsBeginImageContextWithOptions(
            CGSize(width: self.size.width + insets.left + insets.right,
                   height: self.size.height + insets.top + insets.bottom), false, self.scale)
        let _ = UIGraphicsGetCurrentContext()
        let origin = CGPoint(x: insets.left, y: insets.top)
        self.draw(at: origin)
        let imageWithInsets = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return imageWithInsets
    }
}

OLD ANSWER:

import UIKit

extension UIImage {
    func imageWithInsets(insets: UIEdgeInsets) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(
            CGSizeMake(self.size.width + insets.left + insets.right,
                self.size.height + insets.top + insets.bottom), false, self.scale)
        let context = UIGraphicsGetCurrentContext()
        let origin = CGPoint(x: insets.left, y: insets.top)
        self.drawAtPoint(origin)
        let imageWithInsets = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return imageWithInsets
    }
}