Frame versus Bounds

[btc]

It's still not clear to me when to use which.

[btc]

For example, on the Now Playing screen:

    func incoming(info: NowPlayingInfo, forStation station: Station) {
        // BUG: If user taps station and immediately taps the Miniplayer to open
        // this screen, the screen appears without any content. What in the world
        // is happening?

        let p = TwoLinePresenter(forInfo: info)
        titleView.text = p.title
        artistView.text = p.subtitle

        if info.artwork.isPresent(), let c = info.artwork.dominantUIColor() {
            let s = imageView.frame.size
            let placeholder = UIImage.from(color: c, withSize: s)
            guard let str = info.artwork.url500, let url = URL(string: str) else {
                imageView.image = playbackManager?.station?.image
                return
            }
            imageView.af_setImage(withURL: url, placeholderImage: placeholder)
        } else {
            imageView.image = playbackManager?.station?.image
        }
    }

[bsuvorov]

IMO bounds.size == frame.size. frame is location of the view in the superviews coordinate system, where bounds is a window into content of the view.

bounds.x / bounds.y is not 0 or 0 in Scrollviews.

[LeoNatan]

bounds.size == frame.size is not always correct. If you apply a transform to the view, the frame size is all messed up. As a general rule, it is best to use center and bounds, instead of frame.

The bounds origin tell the underlaying layer what portion of the contents to draw. A scroll view uses the bounds origin to manage what gets drawn as the user scrolls.

[btc]

Here's a helpful resource I just found.

[LeoNatan]

Excellent indeed! As usual, Stanford lectures are top notch.