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Swift 4 Protocol-Oriented Programming - Third Edition
book

Swift 4 Protocol-Oriented Programming - Third Edition

by Jon Hoffman
October 2017
Intermediate to advanced
210 pages
5h 32m
English
Packt Publishing
Content preview from Swift 4 Protocol-Oriented Programming - Third Edition

Copy-on-write

Normally, when we pass an instance of a value type, such as a structure, we create a new copy of the instance. This means that if we have a large data structure that contains 50,000 elements, every time we pass that instance, we would have to copy all 50,000 elements. This can have a detrimental impact on the performance of our applications especially, if we pass that instance to numerous functions.

To solve this issue, Apple has implemented the COW feature for all the data structures (Array, Dictionary, and Set) within the Swift standard library. With COW, Swift does not make a second copy of the data structure until a change is made to that data structure. Therefore, if we pass an array to 50,000 elements to another part of ...

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Publisher Resources

ISBN: 9781788470032