loadview
- (void)loadView
{
UIView *contentView = [[UIViewalloc] initWithFrame:[[UIScreenmainScreen] applicationFrame]];
contentView.backgroundColor = [UIColorlightGrayColor];
UILabel *label = [[UILabelalloc] initWithFrame:CGRectMake(0.0f, 0.0f, 320.0f, 30.0f)];
label.text = @"Hello,World";
label.center = contentView.center;
label.textAlignment = UITextAlignmentCenter;
label.backgroundColor = [UIColorclearColor];
[contentView addSubview:label];
self.view = contentView;
}