cduck cduck - 13 days ago 8
Objective-C Question

What is the best way to make a UIButton checkbox?

I am trying to make a standard check box for my iPhone app from a

UIButton
with a title and image. The button image changes between an "unchecked" image and a "checked" image.

At first I tried subclassing
UIButton
but
UIButton
has no
-init***
method to use in my
-init
method.

What is the best way to do this?

Thanks in advance.

Answer

You shouldn't need to subclass the UIButton class. By design, Objective-C favors composition over inheritance.

UIButton is a subclass of UIControl, which has a selected property. You can use this property to toggle the on/off behaviour of a checkbox, just the same way a UISwitch does.

You can attach an action to the button's touched up inside event, and perform the toggling in there, something like this:

// when you setup your button, set an image for the selected and normal states
[myCheckBoxButton setImage:nonCheckedImage forState:UIControlStateSelected];
[myCheckBoxButton setImage:nonCheckedImage forState:UIControlStateNormal];

- (void)myCheckboxToggle:(id)sender
{
    myCheckboxButton.selected = !myCheckboxButton.selected; // toggle the selected property, just a simple BOOL
}
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