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zntfdr |
Lots of performance improvements (both within UIKit and also at app level).
The Render Loop is the process that runs potentially at 120 times every second (if your screen is 120Hz). That makes sure that all the content is ready to go for each frame.
The Render Loop consists of three phases:
- Update Constraints
- Layout
- Display
- Runs from the leaf most views up to the view hierarchy towards the window.
- Runs the opposite direction starting from the window going down towards the leaves.
- Every view gets drawn (if necessary) from window going down
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It is suggested to use interface builder as much as possible to avoid auto layout performance issues
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Interesting behind the scenes of what happens when we activate a new constraint from 12:00 - 17:00
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Don’t avoid using constraints
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Don’t wedge two layouts into one set of constraints: it creates a lot of false dependencies, and is difficult to debug E.g.: final layout:
When actually it should have been two different layouts:
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When in need to change the layout, never remove all the constraints and add them back, change only the necessary ones.
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If a view doesn’t interact with the surrounding views, instead of adding it and removing it (along with its constraints), it’s much better to hide it (isHidden = true)
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If you have shared constraints among your different layouts, initialize them once and never touch them again
- Inequality: very little
- Constant: none
- Priority: needs some amount of work
How to measure? Instruments for Layout!
systemLayoutSizeFitting: is expensive, as everytime the followings need to execute:
