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…
