IOS Study Notes-common NSString Methods

Create a new string and set it to the content of the file specified by path. Use the character encoding enc to return an error on error.

+ (Id) stringWithContentsOfURL :( NSURL *) url encoding :( NSStringEncoding) enc error :( NSError **) error;

Create a new string and set it to the content specified by the url. Use the character encoding enc to return an error on error.

+ (Id) stringWithContentsOfFile :( NSString *) path encoding :( NSStringEncoding) enc error :( NSError **) error;

Create a new Null String

+ (Id) string

Create a new string and set its content to string
+ (Id) stringWithString :( NSString *) string;



Set the new string to astring.

-(Id) initWithString :( NSString *) aString;



Set the string to the content of the file specified by path using the character encoding enc, and return an error on error

-(Id) initWithContentsOfFile :( NSString *) path encoding :( NSStringEncoding) enc error :( NSError **) error;



Set the string to the content of the file specified by path using the character encoding enc, and return an error on error

-(Id) initWithContentsOfURL :( NSURL *) url encoding :( NSStringEncoding) enc error :( NSError **) error;


Returns the number of characters in a string.

-(NSUInteger) length;



Returns the Unicode character of an index (such as I ).
-(Unichar) characterAtIndex :( NSUInteger) index;



Return from (?) Substring from start to end

-(NSString *) substringFromIndex :( NSUInteger) from;



Returns the position starting from the string (?) Substring
-(NSString *) substringToIndex :( NSUInteger);



Returns a substring based on a specified range.
-(NSString *) substringWithRange :( nsange) range;



Compare two strings (Case Insensitive)

-(NSComparisonResult) caseInsensitiveCompare :( NSString *) string;



Compare two strings

-(NSComparisonResult) localizedCompare :( NSString *) string;



Test whether the string starts with aString

-(BOOL) hasPrefix :( NSString *) aString;



Test whether the string ends with aString

-(BOOL) hasSuffix :( NSString *) aString;



Test whether two strings are equal

-(BOOL) isw.tostring :( NSString *) aString;



Returns the upper-case letters of each word in a string, and the lower-case letters of other words.

-(NSString *) capitalizedString;



Returns a string converted to lowercase.

-(NSString *) lowercaseString;



Returns a string converted to uppercase.

-(NSString *) uppercaseString;



Returns a UTF-8 encoded string.

-(_ Strong const char *) UTF8String;



Returns a string of the double type.

-(Double) doubleValue;



Returns a float string to be converted.

-(Float) floatValue;



Returns a string of the int type.

-(Int) intValue;



Returns a string converted to the NSInteger type.

-(NSInteger) integerValue