UItextfield initialized with empty string? not null? nor nil? - ios

Question

i have a uitextfield, when it is initialized and i didn't input any values into it, i found the value of the uitextfield is not null nor nil.
NSString *notes = (notesField.text)?(notesField.text):#"hello";
NSLog(#"notes: %#",notes);
it returns nothing for notes
NSString *notes1;
//or use legnth
if ([notesField.text isEqual:#""]) {
notes1=#"hello";
NSLog(#"empty textfield: %#",notes1);
//then it returns "hello"
}
else
{
notes1=notesField.text;
NSLog(#"not empty textfield: %#",notes1);
}
Why is that? Can I still user ternary operator ?
like this ?
NSString *notes = ([notesField.text length])?(notesField.text):#"hello";

Answer 1

You can use
NSString *notes = ([notesField.text length])?(notesField.text):#"hello";
OR
NSString *notes = ([notesField.text length]==0)?#"hello":(notesField.text);
OR
NSString *notes = ([notesField.text isEqualToString:#""])?#"hello":(notesField.text);
And for the case when your UITextField has no entry (initial case), use the second or third option , that will be beter. NSString *notes = ([notesField.text length])?#"hello":(notesField.text); won't work fine as you expect because notesField.text will be TRUE even if there is no text in textfield. So you should use notesField.text.length or [notesField.text isEqualToString:#""].
Hope its clear now.

Answer 2

The docs for UITextField state
text
The text displayed by the text field.
#property(nonatomic, copy) NSString *text
Discussion
This string is #"" by default.
Note: if compiling under Xcode 5.02 or 5.1 and running in iOS earlier than iOS7, UITextField.text is initialised to nil. If running in iOS7+ it is initialised to #"".
If compiling in Xcode 4.6.3 or earlier then UITextField.text has (always) been initialised to #"", as per the documentation.
Radar bug: 16336863

Answer 3

UITextField must be initializing itself with a non-nil empty string. In situations where you don't care if the string is empty or nil, you can simply check the length property:
if (!notesField.text.length) {
// text is nil or empty
}
Or using the ternary operator:
NSString *s = notesField.text.length ? notesField.text : #"Default";
This works because sending the -length selector to a nil object will return a default value of 0.

Answer 4

That approach will work just fine.
As for why it's an empty string instead of nil, it's generally bad practice to return nil for something unless you want to indicate an error or an uninitialized state. An empty text field has a value. It's just an empty string.