Common nsstring and nsmutablestring usage

Nsstring class is a frequently used class. Here we classify its usage and common methods.

1> Create a string

Nsstring * STR = @ "string content"; // directly use the String constant Assignment Method

Nsstring * STR = [nsstring alloc] init]; // create an empty string object

Nsstring * STR = [nsstring stringwithformat: @ ""]; // create a string using the formatting method of the Class Method

Nsstring * STR = [nsstring stringwithstring: @ ""]; // generate a string by copying an existing string.

Nsstring * STR = [nsstring alloc] initwithstring: @ ""]; // create a string using the instance method

Nsstring * STR = [nsstring alloc] initwithformat: @ ""]; // create a string using the format creation method of the instance method

There are other creation methods, such as converting a C string into an OC string.

 

2> string comparison

-(Nscomparisonresult) Compare :( nsstring *) string;

// Compare two strings and return an enumeration type. The enumerated type has three values-1: indicating ascending order 0: the two are equal. 1: indicates descending order.

-(Nscomparisonresult) Compare :( nsstring *) string options :( nsstringcompareoptions) mask;

// Compare two strings in the specified Method

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The options parameter of the comparison method with restrictions is an enumeration type that has the following common conditions:

1> nscaseinsenstivesearch (1): case-insensitive comparison

2> nsliteralsearch (2): case-sensitive comparison

3> nsbackwardssearch (4): Start from the end

4> nsanchoredsearch (8): normal sequence comparison

5> nsnumericsearch (64): compares the number of characters in a string.

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-(Nscomparisonresult) Compare :( nsstring *) string options :( nsstringcompareoptions) mask range :( nsange) comparerange;

// Select a range and use a comparison method with restrictions within the range * Note that the comparison method is to retrieve the string from the range of str1 and compare it with the entire str2.

-(Bool) isequaltostring :( nsstring *) astring; // you can easily determine whether two strings are equal and return a bool value.

*-(Nscomparisonresult) localizedcompare :( nsstring *) string;

*-(Nscomparisonresult) localizedcaseinsensitivecompare :( nsstring *) string;

// The comparison method of the two localization rules is not clear yet. Note *

 

3> modifying strings

1) common case-sensitive Conversions

-(Nsstring *) uppercasestring; // replace all strings with uppercase letters.

-(Nsstring *) lowercasestring; // change all strings to lowercase letters.

-(Nsstring *) capitalizedstring; // change the first character of all words to uppercase.

2) retrieve the substring

-(Nsstring *) substringfromindex :( nsuinteger) from; // retrieves the character string containing the index position from the index mark position to the end

-(Nsstring *) substringtoindex :( nsuinteger) to; // retrieves the string from the beginning to the position marked by index, excluding the characters at the index position

-(Nsstring *) substringwithrange :( nsange) range; // retrieves the string within the range. Pay attention to the boundary.

3) String concatenation

-(Nsstring *) stringbyappendingstring :( nsstring *) astring; // concatenates one string to another and generates a new string.

-(Nsstring *) stringbyappendingformat :( nsstring *) format; // concatenates A formatted string to another string to generate a new string.

4) string replacement

-(Nsstring *) stringbyreplacingoccurrencesofstring :( nsstring *) Target withstring :( nsstring *) replacement;

// Check whether the string contains the following string and replace it with the specified string.

-(Nsstring *) stringbyreplacingcharactersinrange :( nsange) range withstring :( nsstring *) replacement;

// Replace the specified string with the specified string

-(Nsstring *) stringbyreplacingoccurrencesofstring :( nsstring *) Target withstring :( nsstring *) replacement options :( nsstringcompareoptions) Options range :( nsange) searchrange;

// Check whether the search within the specified range contains the following strings and replace them with the specified strings in options.

 

4> search strings

-(Nsange) rangeofstring :( nsstring *) astring; // locate a string in a string and return a range

-(Nsange) rangeofstring :( nsstring *) astring options :( nsstringcompareoptions) mask;

// Query the position of a string in a specified way and return a range

-(Nsange) rangeofstring :( nsstring *) astring options :( nsstringcompareoptions) mask range :( nsange) searchrange;

// In the specified range, locate the position of a string in the specified way, and return a range

-(Bool) hasprefix :( nsstring *) astring; // determines whether it starts with a string.

-(Bool) hassuffix :( nsstring *) astring; // determines whether it ends with a string.

 

5> reading and writing strings and other methods

-(Nsarray *) componentsseparatedbystring :( nsstring *) separator;

// Split the string into a string, store the string into a string array, and return the Array

-(Nsarray *) componentsseparatedbycharactersinset :( nscharacterset *) separator;

// Split the string into characters in a set, store the string into the string array, and return the Array

-(Nsuinteger) length; // returns the string length.

-(Unichar) characteratindex :( nsuinteger) index; // return the character marked by index

-(Double) doublevalue; // convert a string of pure numbers to the double type.

-(Float) floatvalue; // convert a string of pure numbers into a float type

-(INT) intvalue; // convert a string of pure numbers to the int type.

-(Bool) writetourl :( nsurl *) URL atomically :( bool) useauxiliaryfile encoding :( nsstringencoding) ENC error :( nserror **) error;

// Write the string to the URL. If yes is returned

-(Bool) writetofile :( nsstring *) path atomically :( bool) useauxiliaryfile encoding :( nsstringencoding) ENC error :( nserror **) error;

// Write the string to the specified path. If yes, yes is returned.

+ (Instancetype) stringwithcontentsofurl :( nsurl *) URL encoding :( nsstringencoding) ENC error :( nserror **) error;

// Write the content of the specified URL to the string,

+ (Instancetype) stringwithcontentsoffile :( nsstring *) path encoding :( nsstringencoding) ENC error :( nserror **) error;

// Write the file content in the specified path to the string

 

As a subclass of nsstring, nsmutablestring inherits most of the methods and has some unique methods.

1> Create nsmutablestring

-(ID) initwithcapacity :( nsuinteger) capacity; // instance method. initialize a variable string with the capacity length.

+ (ID) stringwithcapacity :( nsuinteger) capacity; // class method. initialize a variable string with the capacity length.

2> nsmutablestring Modification

-(Void) setstring :( nsstring *) astring; // change the content of an existing variable string to another string

-(Void) insertstring :( nsstring *) astring atindex :( nsuinteger) loc; // insert a string at the position marked by the index

-(Void) deletecharactersinrange :( nsange) range; // delete a string within the specified range

-(Void) appendstring :( nsstring *) astring; // Concatenates the string to an existing string.

-(Void) appendformat :( nsstring *) format; // Concatenates the formatted string to an existing string.

 

The modification method of nsstring and nsmutablestring shows the obvious difference. The nsstring modification method returns an nsstring object, because a new String object must be used to save the modified string. The nsmutablestring modification method returns a null value because it is modified on the original variable string, and the modified string is still the address of the original string.