ios - What is the difference between stringByAddingPercentEscapesUsingEncoding: and stringByReplacingPercentEscapesUsingEncoding: -

What impresses difference between the two methods stringByAddingPercentEscapesUsingEncoding: and stringByReplacingPercentEscapesUsingEncoding: ?

I have read many times and still have not found it.

In addition, is there a way to force those methods to "sign" the signals? ?

I have a base64 encoded (ie letters, numbers, plus slash) menu to urlencode and Using ended CFURLCreateStringByAddingPercentEscapes instead of the method of the above methods ...

  - (NSString *) urlencode: (NSString *) str {return (NSString *) CFBridgingRelease (CFURLCreateStringByAddingPercentEscapes (zero, (CFStringRef __bridge) str, zero, CFSTR ( "+ / "), KCFStringEncodingUTF8)); }    
 
 
  Stringbraidlingprsapapsupingincoding  Unicode * will change the character percent Escape format.  
  stringByReplacingPercentEscapesUsingEncoding  will work in the opposite, save the percentage save in Unicode *.  
 * Actually there is no Unicode, but the encoding you have selected.  
 Example:    NSString * rawText = @ "One Broadway, Cambridge, MA"; NSString * encodedtext = [raw text stringbearingadditionalprint espressoup encoding: NSUFF 8 string encoding]; NSLog (@ "encoded text:% @", encoded text); NSSTING * Decoded Text = [Encoded Text String ByerPlacing Pest Control Escoding Usage: NSTF 8 String Encoding]; NSLog (@ "original text:% @", decoded text);   
 Here is the output:  
  encoded text: a 20% border, 20% of Cambridge,% 20MA text: Broadway, Cambridge, MA   
 loss:  stringByAddingPercentEscapesUsingEncoding  not account ???? T encoded; ampersand safe characters (& amp) and the slash (/)  
 Workaround: Instead Foundation function  CFURLCreateStringByAddingPercentEscapes  uses.  
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