Question

I have a query on this. Please look at the sample code below:

UIButton *button;    
button.tag = 1;

and

int but =  (int)[(UIButton*)sender tag];

The first line I set tag number 1 to button variable, using the .tag method. And in the second line, I used (int)[(UIButton*)sender tag]; to extract and cast the sender into an integer value. My question would be, what is the difference between .tag and tag method?

Answer 1

There should be no difference. Before Objective C 2.0, the dot methods didn’t exist; these were added, but they function as shortcuts to the longer bracketed call.

In your particular code example, in the first code block, button doesn’t hold a pointer to a button. You’d need to call

UIButton *button = [UIButton buttonWithType:UIButtonRoundedRect];
button.tag = 1;

this would set the tag to 1. The second code block takes an existing button and extracts its tag to an int, as you indicated. A better example of parallel methods would be:

button.tag = 1; and [button setTag:1];, or

int tag = button.tag; and int tag = [button tag];