A nice perk of the new swift `defer` statement

The defer statement comes as part of the new error handling model in Swift 2.0. Its primary purpose is to help with cleanup of resources in the face of possible early exits due to errors being thrown.

But the use of defer is not limited to error handling. Just recently, I had to write some code to render an UIImage in a function similar to this:

func renderImage() -> UIImage {
    UIGraphicsBeginImageContextWithOptions(self.size, false, 0.0)
    // Do some drawing
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
}

I was annoyed about the necessity of the temporary image variable when it occured to me that defer could be used to clean up that code:

func renderImage() -> UIImage {
    UIGraphicsBeginImageContextWithOptions(self.size, false, 0.0)
    defer { UIGraphicsEndImageContext() }
    // Do some drawing
    return UIGraphicsGetImageFromCurrentImageContext()
}

There is no need for a temporary variable anymore and the whole code looks a little bit cleaner to me. Its a little change, but one that makes me happy.