stringByReplacingMatchesInString: returns (null) - iphone

Question

Here is my code:
NSRegularExpression * regex;
- (void)viewDidLoad {
NSError *error = NULL;
regex = [NSRegularExpression regularExpressionWithPattern:#"<*>" options:NSRegularExpressionCaseInsensitive error:&error];
}
- (IBAction)findWord {
NSString * fileContents=[NSString stringWithContentsOfFile:[NSString stringWithFormat:#"%#/report1_index1_page1.html", [[NSBundle mainBundle] resourcePath]]];
NSLog(#"%#",fileContents);
NSString * modifiedString = [regex stringByReplacingMatchesInString:fileContents
options:0
range:NSMakeRange(0, [fileContents length])
withTemplate:#"$1"];
NSLog(#"%#",modifiedString);
}
My 'modifiedString' is returning (null).Why?I want to replace any characters between '<' and '>' including '<' and '>' simply by a space.

Answer 1

I am guessing this has a lot to do with the fact that you are assigning an autoreleased object to regex in viewDidLoad. Try adding a retain or move the line to the findWord method.
Regex
The regular expression for matching everything between < and > is incorrect. The correct way would be,
NSError *error = nil;
NSRegularExpression * regex = [NSRegularExpression regularExpressionWithPattern:#"(?<=<).*(?=>)" options:NSRegularExpressionCaseInsensitive error:&error];
if ( error ) {
NSLog(#"%#", error);
}
Replace by space
If you want to replace the matched string with " " then you shouldn't pass $1 as the template. Rather, use " " as the template.
NSString * modifiedString = [regex stringByReplacingMatchesInString:fileContents
options:0
range:NSMakeRange(0, [fileContents length])
withTemplate:#" "];