Missing Anchors
Hey iOS/macOS/watchOS/tvOS developers! I wanna tell you about one simple but interesting code formatting trick we use in Machine Learning Works to describe autolayout constraints.
I was really impressed when I met Apple NSLayoutAnchor API for the first time, which was introduced as a part of iOS 9 SDK. Just want to remind you all of its features:
- centerXAnchor/centerYAnchor
- topAnchor/bottomAnchor
- leftAnchor/rightAnchor
- leadingAnchor/trailingAnchor
- widthAnchor/heightAnchor
- firstBaselineAnchor/lastBaselineAnchor
After awhile I decided that Apple has missed a few possible features:
- sizeAnchor
- edgesAnchor
Size anchor just provides a shorter way to specify width and height with a single CGSize value. Edges anchor allows to specify UIEdgeInset value relatively to superview bounds. Edges anchor also supports some additional modifiers:
- withoutTopAnchor/withoutBottomAnchor
- withoutLeadingAnchor/withoutTrailingAnchor
- withTopAnchor/withBottomAnchor
- withLeadingAnchor/withTrailingAnchor
Some Objective-C examples:
The eagle-eyed of you might have noticed — I’ve just forgot to activate one of the constraints. Thats why I’ve developed a new way to activate them:
Even such syntax is legal with MissingAnchors library:
Finally, I was so impressed with Apple NSLayoutAnchors API that I had backported it to iOS 7 🎉
Also I am thinking about 2-dimensional anchors like centerAnchor/topLeftAnchor/centerRightAnchor… Do you think it will be useful?
