String replacement in Objective-C

You could use the method

- (NSString *)stringByReplacingOccurrencesOfString:(NSString *)target 
                                        withString:(NSString *)replacement

...to get a new string with a substring replaced (See NSString documentation for others)

Example use

NSString *str = @"This is a string";

str = [str stringByReplacingOccurrencesOfString:@"string"
                                     withString:@"duck"];

NSString objects are immutable (they can't be changed), but there is a mutable subclass, NSMutableString, that gives you several methods for replacing characters within a string. It's probably your best bet.

The problem exists in old versions on the iOS. in the latest, the right-to-left works well. What I did, is as follows:

first I check the iOS version:

if (![self compareCurVersionTo:4 minor:3 point:0])

Than:

// set RTL on the start on each line (except the first)  
myUITextView.text = [myUITextView.text stringByReplacingOccurrencesOfString:@"\n"
                                                           withString:@"\u202B\n"];