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iOS Build a Self-Destructing Message iPhone App Using Parse.com as a Backend and Adding Users Signing Up New Users: Part 1 (UIAlertView)

Tommy Choe
Tommy Choe
38,156 Points
Posted by Tommy Choe
Tommy Choe
38,156 Points

Need help understanding syntax for NSString method call 'stringByTrimmingCharactersInSet'

Why is the proper syntax for this method call [self.usernameField.text stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewLineCharacterSet]]; instead of something like [NSCharacterSet stringByTrimmingCharactersInSet: self.usernameField.text?

I'm not understanding how this works.

P.S. I tried reading the document but I still don't understand why this method call is structured like this.

Michael Metzger
Michael Metzger
11,983 Points
Michael Metzger
Michael Metzger
11,983 Points 
Objective-C

//method one 
NSCharacterSet *input = [NSCharacterSet whitespaceAndNewlineCharacterSet];
    NSString *username = [self.usernameField.text stringByTrimmingCharactersInSet:input];

//method two
NSString *username = [self.usernameField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

Both of these syntax achieve the same thing. In method two, you are simply creating the NSCharaterSet instance in the same line. Hope this helps!

1 Answer

landonferrier
landonferrier
25,097 Points

Tommy, here is a full template for the social network application: Click Here.