How to extract and remove scheme name from NSURL? - ios

Question

What is proper way to extract and remove scheme name and :// from a NSURL?
For example:
note://Hello -> #"Hello"
calc://3+4/5 -> #"3+4/5"
so
NSString *scheme = #"note://";
NSString *path = #"Hello";
for later use in:
[[NSNotificationCenter defaultCenter] postNotificationName:scheme object:path];

Answer 1

You can look at it like this (mostly untested code, but you get the idea):
- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url
{
NSLog(#"url: %#", url);
NSLog(#"scheme: %#", [url scheme]);
NSLog(#"query: %#", [url query]);
NSLog(#"host: %#", [url host]);
NSLog(#"path: %#", [url path]);
NSDictionary * dict = [self parseQueryString:[url query]];
NSLog(#"query dict: %#", dict);
}
So you can do this:
NSString * strNoURLScheme =
[strMyURLWithScheme stringByReplacingOccurrencesOfString:[url scheme] withString:#""];
NSLog(#"URL without scheme: %#", strNoURLScheme);
parseQueryString
- (NSDictionary *)parseQueryString:(NSString *)query
{
NSMutableDictionary *dict = [[[NSMutableDictionary alloc] initWithCapacity:6] autorelease];
NSArray *pairs = [query componentsSeparatedByString:#"&"];
for (NSString *pair in pairs) {
NSArray *elements = [pair componentsSeparatedByString:#"="];
NSString *key = [[elements objectAtIndex:0] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSString *val = [[elements objectAtIndex:1] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
[dict setObject:val forKey:key];
}
return dict;
}

Answer 2

My inclination is to roll your own string searching for this:
NSRange dividerRange = [urlString rangeOfString:#"://"];
NSUInteger divide = NSMaxRange(dividerRange);
NSString *scheme = [urlString substringToIndex:divide];
NSString *path = [urlString substringFromIndex:divide];
This does what you've asked for in quite a literal fashion, dividing the URL in half around its scheme. For more advanced handling, you'll have to provide more details.

Answer 3

just use the NSURL's API named: resourceSpecifier :)
and remove the two slashes from the beginning of the string:
NSURL *url = [NSURL URLWithString:#"https://some.url.com/path];
url.resourceSpecifier will result in: //some.url.com/path

Answer 4

Remember, don't fight the frameworks especially when it comes to NSURL. This SO answer has a good breakdown of its abilities. https://stackoverflow.com/a/3693009/142358
NSURL's scheme and path properties are exactly what you want which (assuming the rest of your URL looks like a path) leaves you with this:
NSString *schemeWithDelimiter = [NSString stringWithFormat:#"%#://",[myURL scheme]];
[[NSNotificationCenter defaultCenter] postNotificationName: schemeWithDelimiter object:[myURL path];
No string searching needed!

Answer 5

Swift5, URL extension:
var resourceSpecifier: String {
get {
let nrl : NSURL = self as NSURL
return nrl.resourceSpecifier ?? self.absoluteString
}
}
var simpleSpecifier: String {
get {
let str = self.resourceSpecifier
return str[2..<str.count]
}
}