What are the advantages and disadvantages of different types of data collections?

In iOS development, different types of collections are often used, each with its own advantages and disadvantages:

• NSArray / NSMutableArray

  • Advantages: easy to use, support ordered access by index.
  • Disadvantages: insertions/deletions in the middle of the array can be costly in terms of performance.

• NSDictionary / NSMutableDictionary

  • Advantages: fast key-based access, convenient for storing key-value pairs.
  • Disadvantages: unordered, keys must be hashable.

• NSSet / NSMutableSet

  • Advantages: unique elements, fast search.
  • Disadvantages: unordered, no access by index.

• Swift Array, Dictionary, Set

  • Swift collections are type-safe and optimized, have a convenient syntax, and support value semantics.

The choice of collection depends on the task: if order and quick index access are important — use an array; if fast key-based search is needed — use a dictionary; if element uniqueness is required — use a set.