Question

I’m writing an iPhone application that uses a lot of editable text fields. I’ve been learning a lot about UITextFields and NSStrings by reading various references online, but there are some details that still elude me. When a user puts in an incorrect value for one of my text fields, I throw up an error message and put the text field back to the way it was before their input. For empty text fields, I’ve been doing this:

theTextField.text = @"";

Is this the best way to do this? I just came up with the idea myself, I don’t know if there are any problems with it (other than the fact that it seems to work just fine so far).

Also, does @”” have the same value as a “nil” string? In other words, if I set a string to @”” and then call this:

if (myString) {...}

will the statement return true or false?

One last thing. When an NSString is initialized using this:

NSString *myString = [[NSString alloc] init];

what is that string’s Length value?

Answer 1

Using

theTextField.text = @"";

is absolutely ok. There should be no problems at all.

if (@"")

will evaluate to true. @"" is not the same as nil.

The length of

NSString *myString = [[NSString alloc] init];

is 0.