Remove special symbols at both ends of a string by Stringbytrimmingcharactersinset

1. Introduction to Functions

The NSString class of Apple provides the Stringbytrimmingcharactersinset method to filter the special symbols at both ends of the string, and the function is declared as follows:

-(NSString *) Stringbytrimmingcharactersinset: (Nscharacterset *) set;

The official Apple Note for this function is: Returns a new string made by removing from both ends of the receiver characters contained in a given Cha  Racter set. By official means we know that the function filters out the characters that match the members of the set set at both ends of the string .

2, the function uses the parameter of the function is the Nscharacterset type, so you need to define a Nscharacterset variable before using the function, of course, you can also use the system-provided Nscharacterset constants, such as Whitespaceandnewlinecharacterset, Whitespacecharacterset, etc.

3, examples are as follows:

A. Customize a nscharacterset that contains special symbols that need to be removed

Nscharacterset *set = [Nscharacterset charactersetwithcharactersinstring:@ "... "];

NSString *trimmedstring = [string Stringbytrimmingcharactersinset:set];

Trimmedstring is the filtered string

B. Using a collection of systems

NSString *text1 = [Textfield.text stringbytrimmingcharactersinset:[nscharacterset whitespacecharacterset]];//spaces In addition to both ends

NSString *text = [Textfield.text stringbytrimmingcharactersinset:[nscharacterset Whitespaceandnewlinecharacterset] ;//Remove two paragraphs of space and enter the comment:

notes:

1, Whitespaceandnewlinecharacterset
Returns a character set containing only the whitespace characters space (u+0020) and tab (u+0009) and the newline and next Line characters (u+000a–u+000d, u+0085).

2, Whitespacecharacterset
Returns a character set containing only the in-line whitespace characters space (u+0020) and tab (U+0009).