NSCharacterSet cuts the string - objective-c

Question

I am getting lastest tweet and show it in my app. I put it in a NSMutableString and initialize that string like below in my xmlparser.m file:
- (void) parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
currentNodeContent = (NSMutableString *) [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}
I can get the tweet but somehow it cuts some of the tweets and shows some part of it. For example tweet is
Video games in the classroom? Social media & #technology can change education http://bit.ly/KfGViF #GOVERNING #edtech
but what it shows is:
#technology can change education http://bit.ly/KfGViF #GOVERNING #edtech
Why do you think it is? I tried to initialize currentNodeContent in other ways to but I could not solve the problem.
Do you have any idea why is this happening?

Answer 1

Event-driven (SAX) parsers are free to return only part of the text of a node in a callback. You might only be getting part of the tweet passed in. You should probably accumulate characters in a mutable string until you get a callback indicating the end of the element. See Listing 3 and the surrounding text in this guide.

Answer 2

You've got two problems here:
- (void) parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
currentNodeContent = (NSMutableString *) [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}
Simply casting an NSString to an NSMutableString doesn't work. You have to make a mutable copy yourself or initialise a new NSMutableString using the contents of an NSString.
Furthermore, the text parser is only giving you the last part of the string because it may be interpreting the '&' simply as part of an entity reference, or it may be an entity reference itself.
What you probably want to do is:
Before you begin parsing, initialise currentNodeContent so that it is an empty NSMutableString:
currentNodeContent = [NSMutableString string];
As you are parsing, append the characters to the currentNodeContent:
[currentNodeContent appendString:[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];