Swift string variability

1 You can modify a specific string by assigning it to a variable, or assign it to a constant to ensure that it is not modified:2var variablestring ="Horse"3Variablestring + ="and Carriage"  //variablestring is now "Horse and carriage"4Let constantstring ="Highlander"5Constantstring + ="and another Highlander" //This will report a compilation error (compile-time error)-Constants cannot be modified. 6Note: In Objective-c and Cocoa, you specify whether the string can be modified by selecting two different classes (NSString and nsmutablestring), whether the string in Swift can be modified only by defining a variable or constant, It realizes the unification of various types of variability operations.

Swift string variability