Pretty simple class that extends standard UIButton functionality. Default and selected states can be configured for every button.

It does not need any central manager. Just link the buttons right in Interface Builder:

Alternatively group the buttons using single line of code:

radio1.groupButtons = @[radio1, radio2, radio3];

Select any button, and all other button in the same group become deselected automatically:

radio2.selected = YES; // radio1 and radio3 become deselected

Any button from the group knows which one is selected:

RadioButton* r1 = radio1.selectedButton;
RadioButton* r2 = radio2.selectedButton;
RadioButton* r3 = radio3.selectedButton;
NSAssert (r1==r2 && r2==r3, @"Must be equal");

And a helpful method to select button by tag:

[radio1 setSelectedWithTag:kTagRadio3];

pod 'RadioButton'

sample.zip - Sample app
radio-res-ios.zip - Radio Button images used in the sample

RadioButton is available under the MIT license - fork, modify and use however you want.