1. Collection: A collection (NSSet) is similar to an array (NSArray) in that they store addresses of different objects;However, NSArray is an ordered set, and NSSet is an unordered set.A set is a hash table. Using the hash algorithm, finding elements in the set is faster than the array, but it has no order.1 NSS…
1 Introduction GCC only means GNU C Compiler.After so many years of development, GCC has not only supported the C language;It now also supports Ada language, C++language, Java language, Objective C language, Pascal language, COBO