ios - How to get all NSRange of a particular character in a NSString?

Question

I have two NSStrings: orgText and searchLetter.
I want to highlight every occurrences of the searchLetter in the orgText with a red color.
How can I get the NSRange of all occurrences of the searchLetter ?
for eg :

suppose: orgText = "abcahaiapaoiuiapplma"
         searchLetter = "a".

I want to hightlight all "a" occurrences in "abcahaiapaoiuiapplma" with red color.
Thanks.

Answer 1

I wrote this method for my project - SUITextView with highlight:

- (NSMutableAttributedString*) setColor:(UIColor*)color word:(NSString*)word inText:(NSMutableAttributedString*)mutableAttributedString {

    NSUInteger count = 0, length = [mutableAttributedString length];
    NSRange range = NSMakeRange(0, length);

    while(range.location != NSNotFound)
    {
        range = [[mutableAttributedString string] rangeOfString:word options:0 range:range];
        if(range.location != NSNotFound) {
            [mutableAttributedString setTextColor:color range:NSMakeRange(range.location, [word length])];
            range = NSMakeRange(range.location + range.length, length - (range.location + range.length));
            count++; 
        }
    }

    return mutableAttributedString;
}

And in my category of NSMutableAttributedString:

- (void) setTextColor:(UIColor*)color range:(NSRange)range {
    // kCTForegroundColorAttributeName
    [self removeAttribute:(NSString*)kCTForegroundColorAttributeName range:range]; // Work around for Apple leak
    [self addAttribute:(NSString*)kCTForegroundColorAttributeName value:(id)color.CGColor range:range];
}