force portrait

forceportrait.m

- (void)forcePortrait
{
    if (UIDeviceOrientationIsLandscape([[UIDevice currentDevice] orientation]))
    {
        if ([[UIDevice currentDevice] respondsToSelector:@selector(setOrientation:)])
        {
            int orientationPortrait = UIInterfaceOrientationPortrait;
            NSMethodSignature *sig = [[UIDevice currentDevice] methodSignatureForSelector:@selector(setOrientation:)];
            NSInvocation* invo = [NSInvocation invocationWithMethodSignature:sig];
            [invo setTarget:[UIDevice currentDevice]];
            [invo setSelector:@selector(setOrientation:)];
            [invo setArgument:&orientationPortrait atIndex:2];
            [invo invoke];
        }
    }
}