CFURLCreateStringByAddingPercentEscapes is deprecated in iOS 9, how do I use "stringByAddingPercentEncodingWithAllowedCharacters" - ios

Question

I have the following code:
return (NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)string, NULL, CFSTR(";:#&=+$,/?%#[]"), kCFStringEncodingUTF8);
Xcode says it is deprecated in iOS 9. So, how do I use stringByAddingPercentEncodingWithAllowedCharacters ?
Thanks!

Answer 1

try this
NSString *value = #"<url>";
value = [value stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

Answer 2

The character set URLQueryAllowedCharacterSet contains all characters allowed in the query part of the URL (..?key1=value1&key2=value2) and is not limited to characters allowed in keys and values of such a query. E.g. URLQueryAllowedCharacterSet contains & and +, as these are of course allowed in query (& separates the key/value pairs and + means space), but they are not allowed in a key or a value of such a query.
Consider this code:
NSString * key = "my&name";
NSString * value = "test+test";
NSString * safeKey= [key
stringByAddingPercentEncodingWithAllowedCharacters:
[NSCharacterSet URLQueryAllowedCharacterSet]
];
NSString * safeValue= [value
stringByAddingPercentEncodingWithAllowedCharacters:
[NSCharacterSet URLQueryAllowedCharacterSet]
];
NSString * query = [NSString stringWithFormat:#"?%#=%#", safeKey, safeValue];
query will be ?my&name=test+test, which is totally wrong. It defines a key named my that has no value and a key named name whose value is test test (+ means space!).
The correct query would have been ?my%26name=test%2Btest.
As long as you only deal with ASCII strings or as long as the server can deal with UTF-8 characters in the URL (most web servers today do that), the number of chars you absolutely have to encode is actually rather small and very constant. Just try that code:
NSCharacterSet * queryKVSet = [NSCharacterSet
characterSetWithCharactersInString:#":/?&=;+!##$()',*% "
].invertedSet;
NSString * value = ...;
NSString * valueSafe = [value
stringByAddingPercentEncodingWithAllowedCharacters:queryKVSet
];

Answer 3

Another solution to encode those characters allowed in URLQueryAllowedCharacterSet but not allowed in a key or a value (e.g.: +):
- (NSString *)encodeByAddingPercentEscapes {
NSMutableCharacterSet *charset = [[NSCharacterSet URLQueryAllowedCharacterSet] mutableCopy];
[charset removeCharactersInString:#"!*'();:#&=+$,/?%#[]"];
NSString *encodedValue = [self stringByAddingPercentEncodingWithAllowedCharacters:charset];
return encodedValue;
}