What is the difference between String and NSMutableString?

var firstString: String = "A"

var first2String: String = ""

first2String = firstString

firstString = "B"

var firstString: NSMutableString = "A"

var first2NSString: NSMutableString = ""

first2NSString = firstString

firstString = "B"

CodePudding user response：

String is a Swift native type, and uses value semantics.

NSMutableString is a Foundation Class object that is "toll-free-bridged" with the Swift String type. As a Class object it uses reference semantics.

The NSMutableString class has a few methods that the Swift String type does not.

CodePudding user response：

This is related to the reference and value type