Removing all characters within HTML tag from a string iOS Development

- (void) usingNSRange
{
NSString* str = [NSStringstringWithFormat:@"  
string1  1111    
string 2   22222 
string 3   33333 "];

NSString* startTag = @"
";

NSString* endTag = @"";

    NSString* replacementString = @"";

         while ([str rangeOfString:startTag].length != 0 && [str rangeOfString:endTag].length != 0)

                        {

                  NSRange range1 = [str rangeOfString:startTag];

                     NSRange range2 = [str rangeOfString:endTag];

if(range1.location>range2.location)

   break;

NSRange newRange;

                     newRange.length =range2.location-range1.location+range2.length;

                  newRange.location = range1.location;

                  str = [str stringByReplacingCharactersInRange:newRange withString:replacementString];

         }

}

In the above code, logic is as :

— While loop will be executed unless start and end tag present in it. And operator is there , so if any of the statement returns false , it will stop execution.

— Next, we will get the range of the first occurance of start tag and end tag.

— In case, the location retrieved for start tag is greater then it will break out from the loop. Take this case:

@” test test test test  

”

In this case, end tag appears before start tag and in this case condition will return TRUE.

— Next using start and end location, we calculate the range of the string to be eliminated.

LengthOfString = End Tag Location – Start Tag Location + length of end tag

— And start location of the data to be removed will be the location of start tag.

— And next we will replace the string coming in the calculated range with an empty string.

Method – 2

 (void) usingNSScanner
{
    NSString* str = [NSStringstringWithFormat:@"  
string1  1111    
string 2   22222 
string 3   33333 "];

 

NSString* startTag = @"
";

NSString* endTag = @"";

 

 

NSString* text = nil;

              NSScanner* theScanner;

 

            while([str rangeOfString: startTag].length !=0 && [str rangeOfString: endTag].length !=0)

         {

            theScanner= [NSScanner scannerWithString:str];

            [theScanner scanUpToString: startTag intoString:NULL];

           [theScanner scanUpToString: endTag intoString:&text];

      if (text.length > 0)

         {

NSString* replacementString = [[NSString alloc] initWithFormat:@"%@%@",text, endTag];

str = [str stringByReplacingOccurrencesOfString:replacementString withString:@""];

[replacementString release];

         }

         text =nil;

      }

}

— This approach is similar to first one but instead of calculating start location and length of string, we are scanning the string and taking out the portion of text that has to be removed.

— while condition is same as first approach. Here the new thing is NSScanner, that is provided with html string.

— First, it will scan the string upto start tag and we don’t need that text so we are placing it null.

Next starting from that point where the start tag is found, it will scan upto end tag and place the string that will be pointed by text.

— And that portion of text will be replaced with an empty string in the actual string.

Method – 3

- (void) usingRegularExpression
{
     NSString* str = [NSStringstringWithFormat:@"  
string1  1111    
string 2   22222 
string 3   33333 "];

NSString* startTag = @"
";

NSString* endTag = @"";

NSError* error;

 

NSString* regularExpressionString  = [[NSString alloc] initWithFormat:@"%@.*?%@", startTag, endTag];

 

NSRegularExpression *regex = [NSRegularExpressionregularExpressionWithPattern:regularExpressionString    options:NSRegularExpressionCaseInsensitive

    error:&error];

 

NSString *modifiedString = [regex stringByReplacingMatchesInString:str

options:0

range:NSMakeRange(0, [str length])

withTemplate:@""];

}