objective-c : UITextField 텍스트 유무에 따라 액션 버튼 활성화 판단

snippet.m

UITextField 텍스트 유무에 따라 액션 버튼 활성화 판단

- (BOOL)textField:(UITextField *)theTextField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSString *newText = [theTextField.text stringByReplacingCharactersInRange:range withString:string];
    if ([newText length] > 0) {
        self.doneBarButton.enabled = YES;
    } else {
        self.doneBarButton.enabled = NO;
    }
    return YES;
}


//simpler way to write the above method:
//self.doneBarButton.enabled = the result of the condition;

self.doneBarButton.enabled = ([newText length] > 0);


//( ) parentheses are not really necessary. so can also write it like this

self.doneBarButton.enabled = [newText length] > 0;



//relational operators in Objective-C
//> greater than
//< less than
//>= greater than or equal to <= less than or equal to
//== equal
//!= not equal