iPad custom size of modal view controller

As some other users here, I also had the problem that the origin of the modal view controller was not correct. After some experiments, I found a solution that worked for me:

- (void)viewWillLayoutSubviews{
    [super viewWillLayoutSubviews];   
    self.view.superview.bounds = CGRectMake(0, 0, <width>, <height>);
}