Simple function to replace all occurrences of spaces in a string with plus (+) signs in iPhone OS

Question

I want to use this but need a solution for this..

NSString *googleAddress = @"http://maps.google.com?q=";
googleAddress = [googleAddress stringByAppendingString:self.address];
googleAddress = [googleAddress stringByAppendingString:@"+"];
googleAddress = [googleAddress stringByAppendingString:self.city];
googleAddress = [googleAddress stringByAppendingString:@",+"];
googleAddress = [googleAddress stringByAppendingString:self.state];
googleAddress = [googleAddress stringByAppendingString:@"&t=h"];

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:googleAddress]];

I need to replace all the spaces in the address, city and state values with plus signs to get google maps to work.

Thanks

Answer 1

googleAddress = [googleAddress stringByReplacingOccurancesOfString:@" " withString:@"+"];

Answer 2

I would take a different approach. Here's how I'd do it:

NSString * q = [NSString stringWithFormat:@"%@ %@, %@", self.address, self.city, self.state];

NSDictionary * queryDictionary = [NSDictionary dictionaryWithObjectsAndKeys:q, @"q", @"h", @"t", nil];

NSMutableArray * fields = [NSMutableArray array];
for (NSString * key in queryDictionary) {
  NSString * value = [queryDictionary objectForKey:key];
  NSString * encoded = [NSString stringWithFormat:@"%@=%@", [key URLEncodedString_ch], [value URLEncodedString_ch]];
  [fields addObject:encoded];
}

NSString * queryString = [fields componentsJoinedByString:@"&"];
NSString * googleString = [NSString stringWithFormat:@"http://maps.google.com?%@", queryString];
NSURL * googleURL = [NSURL URLWithString:googleString];
[[UIApplication sharedApplication] openURL:googleURL];

-URLEncodedString_ch can be found here

Why is this better? There are several reasons:

1. The keys in a query string should be URL encoded. Granted that right now they're just one letter that's in the ASCII set, but can you guarantee that they'll always be?
2. The values in a query string should be URL encoded. Right now you're only trying to plus-encode the spaces. What if your address contains an & or =? It would be unusual for an address, but not impossible (especially the & in a street name).
3. This is highly extensible. If you decide to add support for foreign address and need more than a simple ASCII address, it's rather trivial to add the @"UTF-8" and @"oe" object and key to the dictionary for inclusion in the query string.
4. The percent encoding (if you use the category method linked to above) is more accurate than stringByAddingPercentEscapesUsingEncoding:

Answer 3

Have a look at NSString's stringByReplacingOccurrencesOfString:withString: and NSMutableString's replaceOccurrencesOfString:withString:options:range:.

Answer 4

This snippet may be of use to some people, especially since Google treats + and %20 the same.

NSString *escapedUrlString =
   [unescapedString stringByAddingPercentEscapesUsingEncoding:
                    NSASCIIStringEncoding];

Source: http://blog.evandavey.com/2009/01/how-to-url-encode-nsstring-in-objective-c.html