(iPhone) How to customize an UISwitch's text

In the UISwitch Class Reference, it said "The UISwitch class is not customizable". But i saw UISwitch's texts are not "ON/OFF" in some apps, in the UISwitch Class Reference doesn't contain such methods to change the defalut text. I just got the solution from iPhone Dev SDK Forum, someone posted these methods:

- (_UISwitchSlider *) slider {
 return [[self subviews] lastObject];
}

- (UIView *) textHolder {
 return [[[self slider] subviews] objectAtIndex:2];
}

- (UILabel *) leftLabel {
 return [[[self textHolder] subviews] objectAtIndex:0];
}

- (UILabel *) rightLabel {
 return [[[self textHolder] subviews] objectAtIndex:1];
}

- (void) setLeftLabelText: (NSString *) labelText {
 [[self leftLabel] setText:labelText];
}

- (void) setRightLabelText: (NSString *) labelText {
 [[self rightLabel] setText:labelText];
}

or

[(UILabel *)[[[[[[yourSwitch subviews] lastObject] subviews] objectAtIndex:2] subviews] objectAtIndex:0] setText:@"LeftText"];

[(UILabel *)[[[[[[yourSwitch subviews] lastObject] subviews] objectAtIndex:2] subviews] objectAtIndex:1] setText:@"RightText"];

_UISwitchSlider? what's that? I think you must have the same question? we can't find this class in the official reference documents. You can check by youself, it really exists in the official SDK, using [yourSwitch subviews] could show you that your UISwitch has an array of _UISwitchSlider, and then you can finally find your UISwitch contains 2 UILabel objects, and we can change their values.

I don't know if the future SDK will documentation these stuff, and i'm afraid there definitely has some other "hidden" methods, i can't understand why Apple doing this for developer, if they would like to release a SDK for public, they should release the whole documents.