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How to find a UIView subview using viewWithTag()

Swift version: 5.6

Paul Hudson    @twostraws   

If you need a quick way to get hold of a view inside a complicated view hierarchy, you're looking for viewWithTag() – give it the tag to find and a view to search from, and this method will search all subviews, and all sub-subviews, and so on, until it finds a view with the matching tag number. The method returns an optional UIView because it might not find a view with that tag, so unwrap it carefully.

Here's an example:

if let foundView = view.viewWithTag(0xDEADBEEF) {

Easy to remember tags such as 0xDEADBEEF are quite common amongst coders.

NB: Extensive use of viewWithTag() is a sign of poor code structure. It's good for the occasional shortcut, but really shouldn't be relied on for serious development.

You see, if you use viewWithTag() to find some specific nested view then you’re effectively saying “there's a view that I have given a magic number to, and it's definitely a UIImageView (for example), so please find it and use it.” This means you're bypassing all the safety of the Swift compiler: that number might change or be removed, or the view in question might change type or be removed – and neither of those would cause problems or get caught.

If you use viewWithTag() rarely then it's fine, but if you find yourself doing it a lot then really you should be thinking about an alternative – making a custom subclass for your table view cell, for example.

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