iOS Stupid Question. String values

[ErikMadsen]

I'm new to C/ObjC and am wondering why this statement is always true when I known darn well there's no text in the UITextFields referenced...

if(txtEmail.text != @"" && txtPassword.text != @""){
...
}

Many thanks. I'll go back to my corner and put my dunce cap back on until an answer arrives.

 

[AussieSusan]

Objective-C strings are actually an instance of the NSString class - even the @"xxx" literals. Therefore what you are comparing is the addresses of the class instances and so both sides of each '!=' will always be different and so the '!=' will always 'true'.

What you want is something like (of the top of my head):
if( NO == [txtEmail.text isEqualTo""] && NO == [txtPassword.text isEqualTo""])

An alternative is:
if(* NSOrderedSame != [txtEmail.text compare""].........

(I suggest you look up the isEqualTo: and compare: functions to get the syntax right - I'm just going form memory).

Susan

 

[ErikMadsen]

Many thanks, Susan! *removes dunce cap and returns to desk*

if(![txtEmail.text isEqualToString:@""] && ![txtPassword.text isEqualToString:@""]){
[btnLogin setEnabled:YES];
}

Objective-C strings are actually an instance of the NSString class - even the @"xxx" literals. Therefore what you are comparing is the addresses of the class instances and so both sides of each '!=' will always be different and so the '!=' will always 'true'.

What you want is something like (of the top of my head):
if( NO == [txtEmail.text isEqualTo""] && NO == [txtPassword.text isEqualTo""])

An alternative is:
if(* NSOrderedSame != [txtEmail.text compare""].........

(I suggest you look up the isEqualTo: and compare: functions to get the syntax right - I'm just going form memory).

Susan

 

[PhoneyDeveloper]

isEqualTo: doesn't exist on the phone. Use isEqualToString: Even down unda.