Strings - Objective C

The string in Objective C programming language is represented using NSString and its subclass NSMutableString provides ways for creating string objects. The simplest way to create a string object is to use the Objective C @".." construct:

NSString *greeting = @Hello";

A simple example for creating and printing a string is shown below:

#import <Foundation/Foundation.h>
int main()
{
       NSString *greeting = @Hello";
       NSLog(@"Greeting message: %@\n", greeting );
       return 0;
}

S.N.	Method and purpose
1	-(NSString *)capitalizedString; Returns a capitalized representation of the receiver.
2	-(unsigned)characterAtIndex : (NSUInteger)index; Return the character at a given array position.
3	-(double)doubleValue; Return the floating-point value the receiver's text as a double.
4	-(float)floatValue; Return the floating-point value of the receiver's text as a float.
5	-(BOOL)hasPrefix : (NSString *)aString; Return a boolean value that indicates whether a given string matches the begining characters of the receiver.
6	-(BOOL)hasSuffix : (NSString *)aString; Return a boolean value that indicates whether a given string matches the ending characters of the receiver.
7	-(NSInteger)integerValue; Return the NSInteger value of the reciver's text.
8	-(id)initWithFormat : (NSString *)format...; Return an NSString object initialized by using a given format string as a template into which the remaining argument values are substituted.
9	-(BOOL)isEqualToString : (NSString *)aStringl return a boolean value that indicate whether a given string is equal to the reciver using a literal unicode-based comparison.
10	-(NSUInteger)length; Return the number of unicode character in the receiver.
11	-(NSString *)lowercaseString; Return lowercae representation of the receiver/
12	-(NSRange)rangeOfString : (NSString *)aString; Finds and return the range of the first occurence of a given string within the receiver.
13	-(NSString *)stringByAppendingFormat : (NSString *)foramt..;  Return a string made by appending to the receiver a string constructed from a given format string and the following argument.
14	-(NSString *)stringByTrimmingCharactersinSet : (NSCharacterSet *)set; Return a new string made by removing from both ends of the receive characters contained in a given character set.
15	-(NSString *)substringFromIndex : (NSUInteger)atIndex; Return a new string containing the characters of the receiver from the one at a given index to the end.

Following example makes use of few of the above mentioned functions:

#import <Foundation/Foundation.h>
int main()
{
       NSString *str1 = @"Hello";
       NSString *str2 = @"World";
       NSString *str3;
      int len ;
     
      NSAutoreleasePool *pool = [[NSAutoreleasePool]alloc]init];
       
           //uppercase string
       str3  = [str2 uppercaseString];
       NSLog(@"Uppercase String: %@\n", str3 );

          //concatenates str1 and str2
      str3 = [str1 stringByAppedingFormat : @"World"];
      NSLog(@"Concatenated string: %@]n", str3);
 
        //total length of str3 after concatenation
      len = [str3 length];
      NSLog(@"Length of str3 : %d\n", len);
 
     //initwithFormat
    str3 = [[NSString alloc]initWithFormat:@"%@ %@",  str1, str2);
    NSLog(@"Using initwithformat : %@\n", str3);
    [pool drain];

    return 0;
}
       return 0;
}