Occurance of character after specific index - ios

Question

Is there any way to achieve what JAVA function int indexOf(int ch, int fromIndex) do.
Let me explain it:
NSString *steSample = #"This is sample test string";
Now i want to get the index of i but after 2nd index. How can I achieve this.
Thanks in advance

Answer 1

the regex way is too complicated for me :)
can't we just trim it and then look for it?
that'd be 3 lines...
wrapped in a category:
#import <Foundation/Foundation.h>
#interface NSString (Extend)
-(NSUInteger)indexOfSubstring:(NSString*)needle afterIndex:(NSUInteger)index;
#end
#implementation NSString (Extend)
-(NSUInteger)indexOfSubstring:(NSString*)needle afterIndex:(NSUInteger)index {
id str = [self substringFromIndex:index];
NSUInteger i = [str rangeOfString:needle].location;
return i==NSNotFound ? i : i+index;
}
#end
Demo usage:
int main(int argc, char *argv[]) {
#autoreleasepool {
id str = #"#asd#asd";
NSUInteger index = [str indexOfSubstring:#"#" afterIndex:2];
NSLog(#"index of # is: %d", index);
}
}

Answer 2

I'd do something like this:
NSString *_sample = #"This is sample test string";
NSError *_error;
NSRegularExpression *_regExp = [NSRegularExpression regularExpressionWithPattern:#"i" options:NSRegularExpressionCaseInsensitive error:&_error];
NSArray *_matches = [_regExp matchesInString:_sample options:NSMatchingReportCompletion range:NSMakeRange(0, _sample.length)];
[_matches enumerateObjectsUsingBlock:^(NSTextCheckingResult * result, NSUInteger idx, BOOL *stop) {
if (idx == 0) {
NSLog(#"ignoring first occurance...");
} else {
NSLog(#"occurance's index : %d, character's index in string : %d", idx, result.range.location); // that line is simplified for your problem
}
}];
NOTE: you can rearrange the actual if statement, it currently 'skips' the first occurance and prints the rest – but it can be customised for your further wish.
my console shows something like this:
ignoring first occurance...
occurance's index : 1, character's index in string : 5
occurance's index : 2, character's index in string : 23

Answer 3

NSString *steSample = #"This is sample test string";
NSUInteger count = 0, length = [steSample length];
NSRange range = NSMakeRange(0, length);
while(range.location != NSNotFound)
{
range = [steSample rangeOfString: #"i" options:0 range:range];
if(range.location != NSNotFound)
{
range = NSMakeRange(range.location + range.length, length - (range.location + range.length));
count++;
if (count == 2)
{
NSLog(#"%d", range.location); // print 6 which is location of second 'i'
}
}
}