1、在info.plist里面添加如下属性并设置成NO

info.plist.png

2、在 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 方法下添加如下两行代码

[[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationNone];
[[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationNone];

PS：上面的隐藏/显示状态栏的方法在 iOS9 之后被弃用了，'setStatusBarHidden:withAnimation:' is deprecated: first deprecated in iOS 9.0 - Use -[UIViewController prefersStatusBarHidden]

为了 fix warning 重新找到了一个解决办法：

1、在info.plist里面添加如下属性并设置成YES

info.plist.png

2、在BaseViewController里面做如下处理：

添加如下成员变量：
/// 隐藏statusBar
@property (nonatomic, assign) BOOL statusBarHidden;

- (UIStatusBarStyle)preferredStatusBarStyle {
    return UIStatusBarStyleLightContent;
}

- (BOOL)prefersStatusBarHidden {
    return _statusBarHidden;
}

- (void)setStatusBarHidden:(BOOL)statusBarHidden {
    if (_statusBarHidden != statusBarHidden) {
        _statusBarHidden = statusBarHidden;
    }

    if ([self respondsToSelector:@selector(setNeedsStatusBarAppearanceUpdate)]) {
        [self prefersStatusBarHidden];
        [self performSelector:@selector(setNeedsStatusBarAppearanceUpdate)];
    }
}

- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
    return UIStatusBarAnimationNone;
}

在第2点可以不在 BaseViewController 添加成员变量 statusBarHidden，然后在需要添加的ViewController里面添加以下方法即可：

- (UIStatusBarStyle)preferredStatusBarStyle {
    return UIStatusBarStyleLightContent;
}

- (BOOL)prefersStatusBarHidden {
    return NO;
}

- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
   return UIStatusBarAnimationNone;
}