iPhone, differentiate between multiple controls?

Question

What is the best way when setting up a UI for the iPhone to differentiate between multiple items of the same type (i.e. 2 sliders) currently I am assigning the controls unique "tags" and then querying them in Xcode. Is this the way to go or am I missing something else?

-(IBAction)switchChanged:(UISwitch*)senderSwitch {
    if([senderSwitch tag] == 1) {
        NSLog(@"SwitchChanged: Engines");
    }
    ...

gary

Answer 1

Hey Gary! I usually choose similar approach, though I prefer using integer constants instead of 'raw' numbers. Here's an example:

const int VIEW_TAG_A_SWITCH = 1;
const int VIEW_TAG_OTHER_SWITCH = 2;

- (IBAction)switchChanged:(UISwitch*)senderSwitch {
    switch (senderSwitch.tag) {
        case VIEW_TAG_A_SWITCH:
            // do something
            break;
        case VIEW_TAG_OTHER_SWITCH:
            // do something else
            break;
    }
}

This makes code more informational and help you to deal with situations when you need to change the UIView tag value for some reason (this way you only change it once in your nib and once in your code).

It's also very handy to use enums when you need to work with a group of controls. Here's a dummy single selection group of buttons example (something similar to what <input type="option" />):

enum GenderOptionButtons {
    kMaleGenderOptionButton = 10,
    kFemaleGenderOptionButton,
    kUndefinedGenderOptionButton,
    NUM_GENDER_OPTION_BUTTONS
}

- (IBAction)buttonDidTouchUpInside:(UIButton *)senderButton {
    for (int i = kMaleGenderOptionButton; i < NUM_GENDER_OPTION_BUTTONS; i ++) {
        [(UIButton *)[self.view viewWithTag:i] setSelected:NO];
    }

    senderButton.selected = YES;
}

Answer 2

If you don't own direct reference (i.e. IBOutlet) to controls, then the "tag" approach is ok.

One advantage of this approach is that you can have different kind of controls calling the same action method. One major drawback of this approach is you have to keep in sync the tags between IB and XCode.