You need a struct ImageBuffer that wraps a large pixel buffer, keeps value semantics, and avoids needless copies. If you implemented copy-on-write yourself, what would the code skeleton and the key API be?
Keep the storage in a final class that the struct references, and right before a mutation check isKnownUniquelyReferenced; if you're not the sole owner, clone first. The standard collections work this way.
SwiftShort answerAdvanced
You need to put a very large Dictionary, hundreds of thousands of entries, into a struct…
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Memory and ARCShort answerAdvanced
How far is it true that "using a struct means no ARC cost"?
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Memory and ARCShort answerBasics
In Swift you assign a large array to another variable with var b = a and then modify only…
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SwiftShort answerBasics
In Swift, what's the fundamental difference between a struct and a class?
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