Objective C - Extract substring by finding first and second occurrence of a character

Question

I am trying to port my Android app to iOS. I need to extract the string present between the first and second occurrence of the single quote ' character.

For example, from javascript:popUpWindow7('news_details.asp?slno=2029',620,300,100,100,'yes'), I need to extract news_details.asp?slno=2029.

In Java, I did this:

String inputUrl = "javascript:popUpWindow7('news_details.asp?slno=2029',620,300,100,100,'yes')";
StringBuilder url = new StringBuilder();
url.append(inputUrl.substring(inputUrl.indexOf('\'')+1, 
                inputUrl.indexOf('\'',inputUrl.indexOf('\'')+1)));

I can't find any method similar to indexOf in Objective C, so I did the following:

NSUInteger length =0;
NSMutableString* url;

NSString* urlToDecode = @"javascript:popUpWindow7('news_details.asp?slno=2029',620,300,100,100,'yes')";

for (NSInteger i=[urlToDecode rangeOfString:@"\'"].location +1; i<urlToDecode.length; i++) {

    if([urlToDecode characterAtIndex:i]== '\'')
    {
        length = i;
        break;
    }
}

NSRange range = NSMakeRange([urlToDecode rangeOfString:@"\'"].location +1, length);

[url appendString:[urlToDecode substringWithRange:range]];

What am I doing wrong?

Answer 1

The problem with your code is that your range's length is counted from location zero, not from the range's location. A range's length is not the index at the end of the range, but the distance between the range's starting location and its end.

How about this as a simpler alternative:

NSArray *components = [urlToDecode componentsSeparatedByString:@"'"];
if (components.count > 1)
{
    NSString *substring = components[1];
}