presentViewController 是否有系统导航条

这种方式没有导航条

[objc]  view plain  copy

1. ViewController *Controller = [[ViewController alloc] init];  
2. [self presentViewController:Controller animated:YES completion:nil];  

这样就有导航条了

[objc]  view plain  copy

1. ViewController *Controller = [[ViewController alloc] init];  
2. UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:Controller];  
3. [self presentViewController:nav animated:YES completion:nil];