stringByAddingPercentEscapesUsingEncoding was deprecated in 9.0 .How to do this?

URL = [[NSString stringWithFormat:@"%@XYZ",API_PATH]stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

If you want just fast example look at this code:

NSString * encodedString = [@"string to encode" stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLFragmentAllowedCharacterSet]];

Also check List of predefined characters sets

If you want explanation read the documents or at least this topic: How to encode a URL in Swift

You'd read the spec for both functions. Then you would find out for what purpose characters are replaced with escape sequences. From there you would find out the set of allowed characters, which must be documented somewhere.

That's an essential part of changing from junior to normal to senior developer: Find out exactly what your code is supposed to do, which should be defined somewhere, and then make it do what it should do.

stringByAddingPercentEscapesUsingEncoding is probably deprecated because it doesn't know which characters are allowed and sometimes gives the wrong results.