I’m learning to develop in XCode for the iPhone.  Being a long time Microsoft developer I admittedly struggle with some of the most simple things in this new XCode/Objective-C world.  One of my recent struggles was when I  attempted to assign several controls in Interface Builder (or, IB for short) unique Tag attributes and then read them in the IBAction method.  I searched far and wide and finally found the answer.

In my scenario, I had several buttons in my View that I wanted to handle with a single method.  I needed to find a way to differentiate between them to find out which one the user clicked.

Solution:

In IB I created three buttons as shown below.  I then selected each one separately and assigned it a unique ‘Tag’ attribute.  The ‘Tag’ attribute is located on the ‘Button Attributes’ tab of the Inspector.

That part wasn’t much of a challenge.  What, unfortunately, was a challenge was getting this value from within the IBAction method.  First, the action method is declared in my ViewController.h file like any other IBAction method:

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController {
}

- (IBAction)push:(id)sender;

@end

Next, the important part.  I had to find a way to get the actual value in my push method.  After several unsuccessful variations of trying to call [sender tag] directly, I found the answer (shown in bold below):

@implementation ViewController

- (IBAction)push:(id)sender
{
 UIButton *btn = (UIButton *)sender;
 NSInteger tag = [btn tag];
 NSLog(@"Tag: %d", tag);

The answer is actually very simple.  Since sender is a generic object type I had to cast it to a UIButton before I could get to the tag property.

Stay tuned.  At this rate there are many more of these quick samples on the way…