Implement Undo with the Swift Command Pattern
When building an app, requests to “just add an undo button” come up more often than you might expect.
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Follow the trail from foundational concepts to practical engineering decisions.
Single Source of Truth: duplicate information always drifts
Some bugs found just before release follow a familiar pattern. The frontend calculates a 10% discount while the backend uses 15%, or a field marked required in the documentation has disappeared from the actual API. Both codebases are fine. The problem is that the same information exists in two places…
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Legacy Code: Test Existing Behavior Before Refactoring
Run nine boundary cases for a discount function, separate refactoring from policy changes, and see why preserving behavior does not certify its correctness.
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[Swift Basics #3] Swift Properties: Stored, Computed, lazy, didSet—4 Selection Rules
This is part 3 of the Swift basics series. It organizes five property types around selection criteria rather than syntax lists. The key question is simple: is this value stored, computed, and when is it created?
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Swift Bridge Pattern: Separating Abstractions to Prevent Subclass Explosion
When building an app with Swift, you eventually reach a point where classes keep multiplying.
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